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Spadaro O, Youm Y, Shchukina I, Ryu S, Sidorov S, Ravussin A, Nguyen K, Aladyeva E, Predeus AN, Smith SR, Ravussin E, Galban C, Artyomov MN, Dixit VD. Caloric restriction in humans reveals immunometabolic regulators of health span. Science 2022; 375:671-677. [PMID: 35143297 PMCID: PMC10061495 DOI: 10.1126/science.abg7292] [Citation(s) in RCA: 94] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The extension of life span driven by 40% caloric restriction (CR) in rodents causes trade-offs in growth, reproduction, and immune defense that make it difficult to identify therapeutically relevant CR-mimetic targets. We report that about 14% CR for 2 years in healthy humans improved thymopoiesis and was correlated with mobilization of intrathymic ectopic lipid. CR-induced transcriptional reprogramming in adipose tissue implicated pathways regulating mitochondrial bioenergetics, anti-inflammatory responses, and longevity. Expression of the gene Pla2g7 encoding platelet activating factor acetyl hydrolase (PLA2G7) is inhibited in humans undergoing CR. Deletion of Pla2g7 in mice showed decreased thymic lipoatrophy, protection against age-related inflammation, lowered NLRP3 inflammasome activation, and improved metabolic health. Therefore, the reduction of PLA2G7 may mediate the immunometabolic effects of CR and could potentially be harnessed to lower inflammation and extend the health span.
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Affiliation(s)
- O Spadaro
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Y Youm
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - I Shchukina
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - S Ryu
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - S Sidorov
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - A Ravussin
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - K Nguyen
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - E Aladyeva
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - A N Predeus
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - S R Smith
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, FL, USA
| | - E Ravussin
- Pennington Biomedical Research Center, LSU, Baton Rouge, LA, USA
| | - C Galban
- Department of Radiology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - M N Artyomov
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - V D Dixit
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
- Department of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
- Yale Center for Molecular and Systems Metabolism, Yale School of Medicine, New Haven, CT, USA
- Yale Center for Research on Aging, Yale School of Medicine, New Haven, CT, USA
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Zurlo F, Trevisan C, Vitturi N, Ravussin E, Salvò C, Carraro S, Siffi M, Iob I, Saller A, Previato L, Sergi G, de Kreutzenberg S, Maran A, Avogaro A. One-year caloric restriction and 12-week exercise training intervention in obese adults with type 2 diabetes: emphasis on metabolic control and resting metabolic rate. J Endocrinol Invest 2019; 42:1497-1507. [PMID: 31359403 DOI: 10.1007/s40618-019-01090-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 07/22/2019] [Indexed: 01/31/2023]
Abstract
PURPOSE The effect of combined lifestyle interventions (LSI) including dietary and physical activity on metabolic health, energy metabolism and VO2max in diabetic patients has provided mixed results. We evaluated the impact of 1-year caloric restriction (CR), and 12-week supervised structured exercise training (SSET) on metabolic health, RMR and VO2max in obese adults with type 2 diabetes. METHODS After 1-month education for LSI, 33 participants had anthropometric, biochemical and metabolic assessments. They then started CR based on RMR, and 3-month SSET during the months 1-3 (Early-SSET) or 4-6 (Late-SSET). Reassessments were planned after 3, 6 and 12 months. Using a per-protocol analysis, we evaluated parameter changes from baseline and their associations for the 23 participants (11 Early-SSET, 12 Late-SSET) who completed the study. RMR was adjusted (adjRMR) for age, sex, fat-free mass (FFM) and fat mass (FM). RESULTS Compared with baseline, after 6 months we found significant increases in VO2max (+ 14%) and HDL-cholesterol (+ 13%), and reduction in body mass index (- 3%), FM (- 8%) and glycated hemoglobin (HbA1c, - 7%). Training-related caloric expenditure negatively correlated with changes in body weight (p < 0.001), FM (p < 0.001) and HbA1c (p = 0.006). These results were confirmed at the 12-month follow-up. Pooling together all follow-up data, adjRMR changes correlated with changes in glycemia (r = 0.29, p = 0.02), total-cholesterol (r = 0.29, p = 0.02) and VO2max (r = - 0.26,p = 0.02). No significant differences emerged between the Early- and Late-SSET groups. CONCLUSIONS Combined intervention with SSET and CR improved metabolic control. Changes in metabolic health and fitness correlated with changes of adjRMR, which was reduced improving fitness, glycemia and cholesterolemia. CLINICAL TRIAL REGISTRY Trial registration number: NCT03785379. URL of registration: http://clinicaltrials.gov .
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Affiliation(s)
- F Zurlo
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - C Trevisan
- Geriatrics Division, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy.
| | - N Vitturi
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - E Ravussin
- Division of Clinical Sciences Pennington, Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA, 70808, USA
| | - C Salvò
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - S Carraro
- Geriatrics Division, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - M Siffi
- Forum Wellness Club, Via Savelli 120, 35129, Padua, Italy
| | - I Iob
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - A Saller
- Department of Medicine, Clinica Medica 1, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - L Previato
- Department of Medicine, Clinica Medica 1, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - G Sergi
- Geriatrics Division, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - S de Kreutzenberg
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - A Maran
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
| | - A Avogaro
- Metabolic Unit, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padua, Italy
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Stanhope KL, Goran MI, Bosy-Westphal A, King JC, Schmidt LA, Schwarz JM, Stice E, Sylvetsky AC, Turnbaugh PJ, Bray GA, Gardner CD, Havel PJ, Malik V, Mason AE, Ravussin E, Rosenbaum M, Welsh JA, Allister-Price C, Sigala DM, Greenwood MRC, Astrup A, Krauss RM. Pathways and mechanisms linking dietary components to cardiometabolic disease: thinking beyond calories. Obes Rev 2018; 19:1205-1235. [PMID: 29761610 PMCID: PMC6530989 DOI: 10.1111/obr.12699] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/09/2018] [Accepted: 03/31/2018] [Indexed: 12/11/2022]
Abstract
Calories from any food have the potential to increase risk for obesity and cardiometabolic disease because all calories can directly contribute to positive energy balance and fat gain. However, various dietary components or patterns may promote obesity and cardiometabolic disease by additional mechanisms that are not mediated solely by caloric content. Researchers explored this topic at the 2017 CrossFit Foundation Academic Conference 'Diet and Cardiometabolic Health - Beyond Calories', and this paper summarizes the presentations and follow-up discussions. Regarding the health effects of dietary fat, sugar and non-nutritive sweeteners, it is concluded that food-specific saturated fatty acids and sugar-sweetened beverages promote cardiometabolic diseases by mechanisms that are additional to their contribution of calories to positive energy balance and that aspartame does not promote weight gain. The challenges involved in conducting and interpreting clinical nutritional research, which preclude more extensive conclusions, are detailed. Emerging research is presented exploring the possibility that responses to certain dietary components/patterns are influenced by the metabolic status, developmental period or genotype of the individual; by the responsiveness of brain regions associated with reward to food cues; or by the microbiome. More research regarding these potential 'beyond calories' mechanisms may lead to new strategies for attenuating the obesity crisis.
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Affiliation(s)
- K L Stanhope
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - M I Goran
- Department of Preventive Medicine, Diabetes and Obesity Research Institute, University of Southern California, Los Angeles, CA, USA
| | - A Bosy-Westphal
- Institute of Human Nutrition and Food Science, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - J C King
- Children's Hospital Oakland Research Institute, Oakland, CA, USA
| | - L A Schmidt
- Philip R. Lee Institute for Health Policy Studies, University of California, San Francisco, San Francisco, CA, USA.,California Clinical and Translational Science Institute, University of California, San Francisco, San Francisco, CA, USA.,Department of Anthropology, History, and Social Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - J-M Schwarz
- Touro University, Vallejo, CA, USA.,Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - E Stice
- Oregon Research Institute, Eugene, OR, USA
| | - A C Sylvetsky
- Department of Exercise and Nutrition Sciences, Milken Institute School of Public Health, The George Washington University, Washington, DC, USA
| | - P J Turnbaugh
- Department of Microbiology and Immunology, G.W. Hooper Research Foundation, University of California, San Francisco, San Francisco, CA, USA
| | - G A Bray
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - C D Gardner
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - P J Havel
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.,Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - V Malik
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - A E Mason
- Department of Psychiatry, Osher Center for Integrative Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - E Ravussin
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - M Rosenbaum
- Division of Molecular Genetics, Department of Pediatrics, Columbia University, New York, NY, USA
| | - J A Welsh
- Department of Pediatrics, Emory University School of Medicine, Wellness Department, Children's Healthcare of Atlanta, Nutrition and Health Sciences Doctoral Program, Laney Graduate School, Emory University, Atlanta, GA, USA
| | - C Allister-Price
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - D M Sigala
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - M R C Greenwood
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - A Astrup
- Department of Nutrition, Exercise, and Sports, Faculty of Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R M Krauss
- Children's Hospital Oakland Research Institute, Oakland, CA, USA
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Peterson CM, Zhang B, Johannsen DL, Ravussin E. Eight weeks of overfeeding alters substrate partitioning without affecting metabolic flexibility in men. Int J Obes (Lond) 2017; 41:887-893. [PMID: 28262678 PMCID: PMC5461218 DOI: 10.1038/ijo.2017.58] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 01/24/2017] [Accepted: 02/18/2017] [Indexed: 01/07/2023]
Abstract
Background/Objective Impairments in metabolic flexibility and substrate handling are associated with metabolic syndrome. However, it is unknown whether metabolic inflexibility causes insulin resistance. We therefore measured metabolic flexibility and substrate handling before and after 8 weeks of overfeeding in initially healthy adults, as a model of the early stages of insulin resistance. Subjects/Methods Twenty-nine healthy men (27 ± 5 years old; BMI 25.5 ± 2.3 kg/m2) were overfed by 40% above baseline energy requirements for 8 weeks and gained 7.6 ± 2.1 kg of weight. Before and after overfeeding, energy expenditure, substrate oxidation, and metabolic flexibility were measured in 2 ways: a) during 1 day of eucaloric feeding in a whole-room indirect calorimeter, and b) during a two-step hyperinsulinemic-euglycemic clamp. Results Eight weeks of overfeeding decreased insulin sensitivity at low and high doses of insulin (p=0.001 and p=0.06, respectively). This was accompanied by decreases in the respiratory quotient (RQ) while sleeping (0.877 ± 0.020 to 0.864 ± 0.026; p=0.05) and at low insulin levels during the clamp (0.927 ± 0.047 to 0.907 ± 0.032; p=0.01). Overfeeding did not affect metabolic flexibility as measured during a clamp (p≥0.17), but it tended to increase 24-hour metabolic flexibility (awake – sleep RQ) as measured by chamber by 0.010 ± 0.028 (p=0.08). In terms of substrate oxidation, overfeeding increased protein oxidation (13 ± 23 g/day; p=0.003) and tended to increase fat oxidation (6 ± 16 g/day; p=0.07), but did not affect carbohydrate oxidation (p=0.64). Individuals with greater metabolic adaptation to overfeeding had higher carbohydrate oxidation rates (r=0.66, p=8×10−5) but not fat oxidation rates (p=0.09). Conclusions The early stages of insulin resistance are accompanied by modest declines in the RQs during sleep and during a clamp, with no changes in fasting RQ or signs of metabolic inflexibility. Our data therefore suggest that metabolic inflexibility does not cause insulin resistance.
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Affiliation(s)
- C M Peterson
- Human Translational Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA.,Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - B Zhang
- Human Translational Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - D L Johannsen
- Human Translational Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - E Ravussin
- Human Translational Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
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5
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Lam YY, Ravussin E. Indirect calorimetry: an indispensable tool to understand and predict obesity. Eur J Clin Nutr 2016; 71:318-322. [DOI: 10.1038/ejcn.2016.220] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 10/10/2016] [Indexed: 11/09/2022]
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Covington JD, Bray GA, Redman LM, Johannsen DL, Ravussin E. Eight weeks of dietary overfeeding increases renal filtration rates in humans: implications for the pathogenesis of diabetic hyperfiltration. J Intern Med 2015; 278:396-400. [PMID: 25903638 PMCID: PMC4560986 DOI: 10.1111/joim.12377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Diabetic nephropathy is characterized at its onset by glomerular hyperfiltration. Prospective studies in humans measuring filtration rates with weight gain are lacking. We investigated renal filtration following weight gain induced by overfeeding. DESIGN Eight weeks of overfeeding (40% above energy requirements, 44% fat, 15% protein and 41% carbohydrate) as well as a 6-month follow-up after the overfeeding intervention. SUBJECTS Thirty-five participants (age: 26.7 ±5.3 years; body mass index: 25.5 ± 2.2 kg m(-2) ; 29 m/6f). MEASUREMENTS Creatinine clearance rate (Ccr) from 24-h urine collection, estimated glomerular filtration rate (eGFR) from the modification of diet in renal disease (MDRD), insulin sensitivity/glucose disposal rate (GDR) by a euglycemic-hyperinsulinemic clamp, components from basic metabolic panels and serum lipid panels. RESULTS Both eGFR and Ccr increased with overfeeding (P = 0.04) and serum lipids (all P < 0.05), along with a decrease in insulin sensitivity (P = 0.003). Fasting glucose concentration was not affected (P = 0.98), but the per cent change in Ccr correlated positively with the change in GDR with overfeeding (r = 0.39, P = 0.02). Six months following overfeeding, serum glucose was maintained, and no evidence of urinary glucose was observed at any time-point. CONCLUSIONS These data suggest that renal hyperfiltration may act as a mechanism to preserve insulin sensitivity through maintenance of systemic glucose homoeostasis with caloric excess.
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Affiliation(s)
- J D Covington
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA.,School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - G A Bray
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - L M Redman
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - D L Johannsen
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - E Ravussin
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
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Samocha-Bonet D, Dixit VD, Kahn CR, Leibel RL, Lin X, Nieuwdorp M, Pietiläinen KH, Rabasa-Lhoret R, Roden M, Scherer PE, Klein S, Ravussin E. Metabolically healthy and unhealthy obese--the 2013 Stock Conference report. Obes Rev 2014; 15:697-708. [PMID: 25059108 PMCID: PMC4519075 DOI: 10.1111/obr.12199] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 05/16/2014] [Accepted: 05/18/2014] [Indexed: 12/12/2022]
Abstract
Obesity is closely associated with cardiovascular diseases and type 2 diabetes, but some obese individuals, despite having excessive body fat, exhibit metabolic health that is comparable with that of lean individuals. The 'healthy obese' phenotype was described in the 1980s, but major advancements in its characterization were only made in the past five years. During this time, several new mechanisms that may be involved in health preservation in obesity were proposed through the use of transgenic animal models, use of sophisticated imaging techniques and in vivo measurements of insulin sensitivity. However, the main obstacle in advancing our understanding of the metabolically healthy obese phenotype and its related long-term health risks is the lack of a standardized definition. Here, we summarize the proceedings of the 13th Stock Conference of the International Association of the Study of Obesity. We describe the current research and highlight the unanswered questions and gaps in the field. Better understanding of metabolic health in obesity will assist in therapeutic decision-making and help identify therapeutic targets to improve metabolic health in obesity.
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Affiliation(s)
- D Samocha-Bonet
- Garvan Institute of Medical Research, University of New South Wales, Sydney, NSW, Australia
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Harrington DM, Martin CK, Ravussin E, Katzmarzyk PT. Activity related energy expenditure, appetite and energy intake: potential implications for weight management. Appetite 2013; 67:1-7. [PMID: 23523668 DOI: 10.1016/j.appet.2013.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 01/30/2013] [Accepted: 03/12/2013] [Indexed: 11/19/2022]
Abstract
The aim was to investigate relationships between activity related energy expenditure (AREE), appetite ratings and energy intake (EI) in a sample of 40 male (26.4years; BMI 23.5kg/m(2)) and 42 female (26.9years; BMI 22.4kg/m(2)) participants. AREE was expressed as the residual value of the regression between total daily EE (by doubly labeled water) and resting EE (by indirect calorimetry). EI was measured using an ad libitum buffet meal and visual analogue scales measured subjective appetite ratings before and after the meal. AREE was divided into low, middle and high sex-specific tertiles. General linear models were used to investigate differences in appetite ratings and EI across AREE tertiles. Before the meal, males in the high AREE tertile had significantly lower desire to eat and lower prospective food consumption and higher feelings of fullness compared to those in the low tertile. Males in the middle tertile had significantly higher satiety quotients after the meal and lower EI compared to the other tertiles. No significant differences across tertiles were found in females. Sex differences in relationships between AREE, appetite ratings and EI may lead to differing patterns of EI and subsequent weight maintenance.
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Affiliation(s)
- D M Harrington
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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9
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Abstract
Food intake rate has previously been derived from observation of eating behavior in laboratory settings or in public eating establishments. Although it has been suggested that obese individuals eat faster than lean individuals, observations of such an "obese eating style" have yielded mixed results. In the present study, the relationship between ad-libitum food intake rate and obesity was evaluated over 4 days on a metabolic ward in 28 healthy Pima Indian men (Mean +/- SD; 29 +/- 7 y, 100.4 +/- 27.1 kg, 33 +/- 10% body fat) using an automated food selection system containing a large variety of foods. Total energy intake averaged 18829 +/- 3299 kJ/d consisting of 47 +/- 4, 40 +/- 3, and 13 +/- 1 percent of carbohydrate, fat and protein, respectively. The average meal duration was 25 +/- 7 min. Food intake rate was 68 +/- 21 g/min while carbohydrate, fat and protein intake rates were 23 +/- 6, 9 +/- 3 and 6 +/- 2 g/min, respectively. Food intake rate correlated negatively with % body fat (r = -0.61, P < 0.01). Similar relationships were found between the intake rates of carbohydrate, fat and protein and body fatness. Only prospective studies will indicate whether a slow food intake rate may contribute to the etiology of obesity by possibly reducing satiety.
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Affiliation(s)
- R Rising
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 4212 North Sixteenth Street, Room 541, Phoenix, Arizona 85016, USA
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10
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Galgani JE, Ravussin E. Postprandial whole-body glycolysis is similar in insulin-resistant and insulin-sensitive non-diabetic humans. Diabetologia 2012; 55:737-42. [PMID: 22173627 PMCID: PMC4360888 DOI: 10.1007/s00125-011-2413-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 11/21/2011] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS Insulin resistance is characterised by impaired glucose utilisation when measured by a euglycaemic-hyperinsulinaemic clamp. We hypothesised that, in response to postprandial conditions, non-diabetic individuals would have similar intracellular glycolytic and oxidative glucose metabolism independent of the degree of insulin resistance. METHODS Fourteen (seven male) sedentary, insulin-sensitive participants (mean ± SD: BMI 25 ± 4 kg/m²; age 39 ± 10 years; glucose disposal rate 9.4 ± 2.1 mg [kg estimated metabolic body size]⁻¹ min⁻¹) and 14 (six male) sedentary, non-diabetic, insulin-resistant volunteers (29 ± 4 kg/m²; 34 ± 13 years; 5.3 ± 1.2 mg [kg estimated metabolic body size]⁻¹ min⁻¹) received after a 10 h fast 60 g glucose plus 15 g [6,6-²H₂]glucose. Serum glucose and insulin concentrations, plasma ²H enrichment and whole-body gas exchange were determined before glucose ingestion and hourly thereafter for 4 h. Plasma ²H₂O production is an index of glycolytic disposal. On day 2, participants received a weight-maintenance diet. On day 3, a euglycaemic-hyperinsulinaemic clamp was performed. RESULTS Insulin-resistant individuals had about a twofold higher postprandial insulin response than insulin-sensitive individuals (p = 0.003). Resting metabolic rate was similar in the two groups before (p = 0.29) and after (p = 0.33-0.99 over time) glucose ingestion, whereas a trend for blunted glucose-induced thermogenesis was observed in insulin-resistant vs insulin-sensitive individuals (p = 0.06). However, over the 4 h after the 75 g glucose ingestion, glycolytic glucose disposal was the same in insulin-sensitive and insulin-resistant individuals (36.5 ± 3.7 and 36.2 ± 6.4 mmol, respectively; p = 0.99). Similarly, whole-body carbohydrate oxidation did not differ between the groups either before or after glucose ingestion (p = 0.41). CONCLUSIONS/INTERPRETATION Postprandial hyperinsulinaemia and modest hyperglycaemia overcome insulin resistance by enhancing tissue glucose uptake and intracellular glucose utilisation.
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Affiliation(s)
- J E Galgani
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Clasificador 7, Santiago, Chile.
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Tam CS, Berthoud HR, Bueter M, Chakravarthy MV, Geliebter A, Hajnal A, Holst J, Kaplan L, Pories W, Raybould H, Seeley R, Strader A, Ravussin E. Could the mechanisms of bariatric surgery hold the key for novel therapies? report from a Pennington Scientific Symposium. Obes Rev 2011; 12:984-94. [PMID: 21729236 PMCID: PMC4048708 DOI: 10.1111/j.1467-789x.2011.00902.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bariatric surgery is the most effective method for promoting dramatic and durable weight loss in morbidly obese subjects. Furthermore, type 2 diabetes is resolved in over 80% of patients. The mechanisms behind the amelioration in metabolic abnormalities are largely unknown but may be due to changes in energy metabolism, gut peptides and food preference. The goal of this meeting was to review the latest research to better understand the mechanisms behind the 'magic' of bariatric surgery. Replication of these effects in a non-surgical manner remains one of the ultimate challenges for the treatment of obesity and diabetes. Promising data on energy metabolism, gastrointestinal physiology, hedonic response and food intake were reviewed and discussed.
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Affiliation(s)
- C S Tam
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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12
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Abstract
Obesity is a worldwide epidemic and there is an urgent need for the development of effective pharmacological therapies that target the metabolic and behavioral factors of body weight regulation. Serotonin (5-HT) has been implicated as a critical factor in the short-term (meal-by-meal) regulation of food intake and pharmaceutical companies have invested millions of dollars to discover and develop drug targets for the serotonergic pathway. Lorcaserin is a novel selective agonist of the 5-HT(2C) receptor for weight loss therapy. Preclinical and clinical studies indicate lorcaserin is well tolerated and not associated with cardiac valvulopathy or pulmonary hypertension suggesting that lorcaserin is a selective 5-HT(2C) receptor agonist and has little or no activation of the 5-HT(2B) and 5-HT(2A) receptors, respectively. Lorcaserin acts to alter energy balance through a reduction in energy intake and without an increase in energy expenditure and achieved the U.S. Food and Drug Administration guidelines for weight loss efficacy. It remains to be determined whether or not lorcaserin will be approved for the long-term management of obesity.
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Affiliation(s)
- L M Redman
- Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
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13
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Larson-Meyer DE, Newcomer BR, Ravussin E, Volaufova J, Bennett B, Chalew S, Cefalu WT, Sothern M. Intrahepatic and intramyocellular lipids are determinants of insulin resistance in prepubertal children. Diabetologia 2011; 54:869-75. [PMID: 21181394 PMCID: PMC3053439 DOI: 10.1007/s00125-010-2022-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/18/2010] [Indexed: 01/24/2023]
Abstract
AIMS/HYPOTHESIS We hypothesised that ectopic fat deposition is present in liver and skeletal muscle before puberty and that both are potentially important factors in the early pathogenesis of insulin resistance. METHODS Proton magnetic resonance spectroscopy was used to evaluate intramyocellular and intrahepatic lipids in 50 male and 42 female multi-ethnic, prepubertal (Tanner < 2) children (8.1 ± 0.8 years; 35.4 ± 10.7 kg; 27.9 ± 8.3% body fat; means ± SD). Intramyocellular lipid was measured in soleus muscle and intrahepatic lipid in the middle right lobe. Abdominal fat was measured by magnetic resonance imaging, body fat by dual energy X-ray absorptiometry, and insulin resistance using homeostatic model assessment. RESULTS Intrahepatic lipid ranged from 0.11% to 4.6% relative to the liver water signal (mean 0.79 ± 0.79%) whereas intramyocellular lipid ranged from 0.13% to 1.86% relative to the muscle water signal (mean 0.51 ± 0.28%). Intramyocellular and intrahepatic lipids were significantly correlated with total adiposity (r = 0.49 and 0.59), abdominal adiposity (r = 0.44 and 0.54), and each other (r = 0.39, p < 0.05, Spearman). Both intramyocellular and intrahepatic lipid were positively correlated with fasting insulin (r = 0.37 and 0.38 respectively) and insulin resistance (r = 0.37 and 0.37; p < 0.01). After adjustment for race and sex, the relations between ectopic fat and insulin resistance remained, whereas both disappeared when further adjusted for body fat or BMI z scores. CONCLUSIONS/INTERPRETATIONS These results suggest that typical relations between body composition, ectopic fat and insulin resistance are present in children before puberty. Thus, interventions aimed at reducing adiposity have the potential to decrease ectopic fat accumulation, delay the onset of insulin resistance and decrease the risk for development of type 2 diabetes in children.
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Affiliation(s)
- D E Larson-Meyer
- Department of Family and Consumer Sciences Human Nutrition, Dept 3354, University of Wyoming, 1000 E, University Avenue, Laramie, WY 82071, USA.
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14
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Abstract
Energy homeostasis is critical for the survival of species. Therefore, multiple and complex mechanisms have evolved to regulate energy intake and expenditure to maintain body weight. For weight maintenance, not only does energy intake have to match energy expenditure, but also macronutrient intake must balance macronutrient oxidation. However, this equilibrium seems to be particularly difficult to achieve in individuals with low fat oxidation, low energy expenditure, low sympathetic activity or low levels of spontaneous physical activity, as in addition to excess energy intake, all of these factors explain the tendency of some people to gain weight. Additionally, large variability in weight change is observed when energy surplus is imposed experimentally or spontaneously. Clearly, the data suggest a strong genetic influence on body weight regulation implying a normal physiology in an 'obesogenic' environment. In this study, we also review evidence that carbohydrate balance may represent the potential signal that regulates energy homeostasis by impacting energy intake and body weight. Because of the small storage capacity for carbohydrate and its importance for metabolism in many tissues and organs, carbohydrate balance must be maintained at a given level. This drive for balance may in turn cause increased energy intake when consuming a diet high in fat and low in carbohydrate. If sustained over time, such an increase in energy intake cannot be detected by available methods, but may cause meaningful increases in body weight. The concept of metabolic flexibility and its impact on body weight regulation is also presented.
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Affiliation(s)
- J Galgani
- Human Physiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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15
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Abstract
BACKGROUND Energy or calorie restriction (CR) has consistently been shown to produce weight loss and have beneficial health effects in numerous species, including primates and humans. Most individuals, however, are unable to sustain weight losses induced through reductions in energy intake, potentially due to increased hunger levels. The effects that prolonged CR has on subjective aspects of appetite have not been well studied. Thus, the present study tested the effect of 6 months of caloric restriction on appetite in healthy, overweight men and women. METHODS Forty-eight overweight men and women with a body mass index (BMI; kg m(-2)) between 25-29.9 took part in a 6-month study and were randomised into one of four groups: healthy diet (control); 25% CR; 12.5% CR plus exercise (12.5% increased energy expenditure; CR + EX); low-calorie diet [LCD; 3724 kJ day(-1) (890 kcal day(-1)) until 15% of initial body weight was lost, then maintenance]. Appetite markers (i.e. hunger, fullness, desire to eat, etc.) were assessed weekly during a fasting state. RESULTS Body weight was significantly reduced in all three energy-restricted groups (CR = -10.4 +/- 0.9%; CR + EX = -10.0 +/- 0.8%; and LCD = -13.9 +/-0.7%), indicating that participants were adherent to their energy restriction regimen, whereas the healthy diet control group remained weight stable (control = -1.0 +/- 1.1%). Despite these significant weight losses, appetite ratings of participants in the three energy-restricted groups at month 6 were similar to the weight stable control group. CONCLUSIONS CR regimens with low fat diets producing significant weight losses have similar effects on appetite markers over a 6-month time period compared to a weight stable control group.
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Affiliation(s)
- S D Anton
- Pennington Biomedical Research Center, Baton Rouge, LA, USA.
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16
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Koska J, Stefan N, Dubois S, Trinidad C, Considine RV, Funahashi T, Bunt JC, Ravussin E, Permana PA. mRNA concentrations of MIF in subcutaneous abdominal adipose cells are associated with adipocyte size and insulin action. Int J Obes (Lond) 2009; 33:842-50. [PMID: 19506561 PMCID: PMC4205943 DOI: 10.1038/ijo.2009.106] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Objective To determine whether the mRNA concentrations of inflammation response genes in isolated adipocytes and in cultured preadipocytes are related to adipocyte size and in vivo insulin action in obese individuals. Design Cross-sectional inpatient study. Subjects Obese Pima Indians with normal glucose tolerance. Measurements Adipocyte diameter (by microscope technique; n=29), expression of candidate genes (by quantitative real-time PCR) in freshly isolated adipocytes (monocyte chemoattractant protein [MCP] 1 and MCP2, macrophage inflammatory protein [MIP] 1α, MIP1β and MIP2, macrophage migration inhibitory factor [MIF], tumor necrosis factor alpha, interleukin [IL] 6 and IL8; n=22) and cultured preadipocytes (MCP1, MIP1α, MIF, IL6 and matrix metalloproteinase 2; n=33) from subcutaneous abdominal adipose tissue (by aspiration biopsy, n=34), body fat by dual-energy X-ray absorptiometry, glucose tolerance by 75-gram oral glucose tolerance test, and insulin action by euglycemic-hyperinsulinemic clamp (insulin infusion rate 40 mU/m2.min)(all n=34). Results MIF was the only gene whose expression in both freshly isolated adipocytes and cultured preadipocytes was positively associated with adipocytes diameter and negatively associated with peripheral and hepatic insulin action (all P<0.05). In multivariate analysis, the association between adipocyte MIF mRNA concentrations and adipocytes diameter was independent of percent body fat (P=0.03), whereas adipocyte MIF mRNA concentrations but not adipocytes diameter independently predicted peripheral insulin action. The mRNA expression concentrations of MIF gene in adipocytes were not associated with plasma concentrations of MIF, but were negatively associated with plasma adiponectin concentrations (P=0.004). In multivariate analysis, adipocyte MIF RNA concentrations (P=0.03) but not plasma adiponectin concentrations (P=0.4) remained a significant predictor of insulin action. Conclusions Increased expression of MIF gene in adipose cells may be an important link between obesity characterized by enlarged adipocytes and insulin resistance in normal glucose tolerant people.
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Affiliation(s)
- J Koska
- Obesity and Diabetes Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health/DHHS, Phoenix, AZ, USA.
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17
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Abstract
In the 1970s and 1980s, it was observed that rodents could offset excess calories ingested when they were fed a human-like 'cafeteria diet'. Although it was erroneously concluded that this so-called diet-induced thermogenesis was because of brown adipose tissue (BAT), it led to efforts to test whether variations in brown fat in humans may explain the susceptibility to obesity. However, from evidence on the inability of ephedrine or beta-3 adrenergic agonists to induce BAT thermogenesis, it was concluded that the thermogenic role of BAT was unimportant in adult humans largely because humans had low numbers of brown adipocytes. Solid evidence on the actual numbers of brown adipocytes in humans was not available. We are now re-evaluating the role of BAT for the treatment of obesity given the following recent observations (i) studies in nuclear medicine by using PET/CT scanning reveal the presence of BAT in adult humans; and (ii) recent data suggest that a new transcription factor called PDRM16 may control the induction of BAT. These recent discoveries should revamp our effort to target the molecular development of brown adipogenesis in the treatment of obesity.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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18
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Carr R, Erondu N, Gonzalez C, Gumbiner B, Musser B, Lu K, Capece R, Klein S, Ravussin E, Amatruda J, Heymsfield S. EFFECTS OF TARANABANT, A NOVEL CANNABINOID 1 RECEPTOR (CB-1R) INVERSE AGONIST, ON WEIGHT REDUCTION IN OBESE PATIENTS OVER 12 WEEKS. ATHEROSCLEROSIS SUPP 2008. [DOI: 10.1016/s1567-5688(08)70835-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Anton SD, Martin CK, Redman L, York-Crowe E, Heilbronn LK, Han H, Williamson DA, Ravussin E. Psychosocial and behavioral pre-treatment predictors of weight loss outcomes. Eat Weight Disord 2008; 13:30-7. [PMID: 18319635 DOI: 10.1007/bf03327782] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
This study tested whether baseline behavioral and psychological variables predict weight and fat loss among overweight, non-obese individuals participating in a six-month calorie restriction trial. Participants (N=48) were randomly assigned to four groups, three of which included a calorie restriction program and one of which served as a healthy diet weight maintenance control. For the purposes of this study, data were analyzed only for participants assigned to the three calorie restriction groups (n=36). Ten psychological and behavioral measures were investigated through principal components factor analysis to examine whether these measures were assessing similar or distinct psychological and behavioral constructs. Based on the obtained six-factor solution, one measure from each domain was selected for inclusion in hierarchical regression analyses, which was used to test the relative importance of psychosocial and behavioral variables in predicting percent weight and fat loss over six months. After controlling for demographic and treatment variables, the behavioral and psychological measures of negative mood states, poor psychosocial functioning, and somatic symptoms were associated with less weight loss (R2=0.68, p<0.001) and fat loss (R2=0.65, p<0.001) over six months. Among overweight individuals, poor psychological adjustment, somatic symptoms, and negative mood states appear to form a psychosocial profile that is predictive of less weight and fat loss in calorie restriction programs.
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Affiliation(s)
- S D Anton
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, USA
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20
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Lê KA, Faeh D, Stettler R, Debard C, Loizon E, Vidal H, Boesch C, Ravussin E, Tappy L. Effects of four-week high-fructose diet on gene expression in skeletal muscle of healthy men. Diabetes & Metabolism 2008; 34:82-5. [DOI: 10.1016/j.diabet.2007.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 08/02/2007] [Accepted: 08/16/2007] [Indexed: 01/14/2023]
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21
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Jackman MR, Ravussin E, Rowe MJ, Pratley R, Milner MR, Willis WT. Effect of a polymorphism in the ND1 mitochondrial gene on human skeletal muscle mitochondrial function. Obesity (Silver Spring) 2008; 16:363-8. [PMID: 18239645 DOI: 10.1038/oby.2007.40] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE A non-silent polymorphism in the mitochondrial coding region of the ND1 gene, a subunit of reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase is associated with resting metabolic rate (RMR) in 245 non-diabetic Pima Indians. The purpose of this investigation was to determine the effect of the ND1 gene polymorphism on mitochondrial function in 14 male Pima Indians. METHODS AND PROCEDURES Seven subjects with an A at site 3547 of the ND1 gene (Ile at amino acid 81), and seven with a G at this site (Val) were studied. Mitochondria were isolated from 0.8 to 1.5 g of skeletal muscle obtained by needle biopsy of the lateral quadriceps muscle. In intact mitochondria, maximal (state-3) and resting (state-4) respiration rates were measured polarographically at 37 degrees C with a variety of single substrates or substrate combinations. Disrupted mitochondria were analyzed for maximal capacities through the entire electron transport chain (ETC) (NADH oxidase (NADHOX)), as well as through a segment of Complex I that is independent of the ND1 component (NADH-ferricyanide (NADH-FeCN) reductase). RESULTS Mitochondria were well coupled and exhibited higher respiratory control ratios (RCRs) than rodent muscle. There were no differences between the two groups for any of the measured parameters. DISCUSSION These results indicate that the cause of the observed association between RMR and the ND1 polymorphism is not related to in vitro mitochondrial function.
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Affiliation(s)
- Matthew R Jackman
- Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, Denver, CO, USA.
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22
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Ravussin E, Redman LM. Caloric restriction and longevity. Journ Annu Diabetol Hotel Dieu 2007:111-125. [PMID: 18610763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, 6400 Perkins Rd, Baton Rouge, LA 70808, USA
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23
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Abstract
The agouti-related protein is a powerful orexigenic peptide. A rare mutation, +79G>A, was identified in its minimal promoter in two white carriers. Comparison of the 45-year-old male proband, who was also a carrier of the common Ala67Thr polymorphism, with an age- and weight-matching wild-type population showed marginal differences for resting metabolic rate (RMR) and body mass index. The second carrier however was an obese 57-year-old female with reduced RMR. Functional analysis in hypothalamus- and periphery-derived cell lines showed reduced promoter activity for the +79A allele in the adrenocortical cells only, suggesting that it could affect the peripheral expression levels of AgRP. The +79G>A mutation could predispose to body weight gain (as suggested by the phenotype of the second carrier), but it could only affect the proband at an older age as he may be protected by the Ala67Thr polymorphism that is associated with resistance to late-onset fatness.
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Affiliation(s)
- M A Sözen
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA.
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24
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Esparza-Romero J, Valencia ME, Ravussin E, Schulz LO, Bennett PH. Insulin Resistance (HOMA-IR) in Non-Diabetics Mexican and US Pima Indians: Role of Environment. Am J Epidemiol 2006. [DOI: 10.1093/aje/163.suppl_11.s160-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Schulz LO, Harper IT, Smith CJ, Kriska AM, Ravussin E. Energy intake and physical activity in Pima Indians: comparison with energy expenditure measured by doubly-labeled water. ACTA ACUST UNITED AC 2006; 2:541-8. [PMID: 16355515 DOI: 10.1002/j.1550-8528.1994.tb00103.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To test the validity of survey techniques for measuring diet and activity patterns of Pima Indians, sequential 24-hour recalls, a food frequency questionnaire (FFQ), and an activity questionnaire were compared to free-living energy expenditure. Total energy expenditure (TEE) measured by doubly labeled water was 13.27 +/- 2.95 MJ/d for the 12 males (mean +/- SD: 35 +/- 14 yr; 97 +/- 35 kg; 32 +/- 9% body fat) and 11.67 +/- 1.85 MJ/d for the 9 females (31 +/- 13 yr; 106 +/- 32 kg; 49 +/- 6% body fat). Energy intake assessed by 24-hour recall was 13.59 +/- 7.81 MJ/d for men and 9.29 +/- 2.77 MJ/d for women, compared to 12.84 + 2.85 and 9.40 + 2.61 MJ/d for men and women, respectively, by FFQ. Both dietary methods indicated significant underreporting by women when compared to TEE. Energy intake assessed by FFQ was significantly correlated with TEE (r=0.48, p=0.03). This was true with 24-hour recall energy intake only when data from two extremely large alcohol consumers were eliminated (r=0.64, p=0.03, N=19). Although a low level of activity was apparent, the activity questionnaire produced significant correlations with measurements of energy expenditure and therefore represents an important tool for examining the relationship between physical activity and diseases.
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Affiliation(s)
- L O Schulz
- Department of Health Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
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26
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Heilbronn L, Smith SR, Ravussin E. Failure of fat cell proliferation, mitochondrial function and fat oxidation results in ectopic fat storage, insulin resistance and type II diabetes mellitus. Int J Obes (Lond) 2005; 28 Suppl 4:S12-21. [PMID: 15592481 DOI: 10.1038/sj.ijo.0802853] [Citation(s) in RCA: 290] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND It is widely accepted that increasing adiposity is associated with insulin resistance and increased risk of type II diabetes. The predominant paradigm used to explain this link is the portal/visceral hypothesis. This hypothesis proposes that increased adiposity, particularly in the visceral depots, leads to increased free-fatty acid flux and inhibition of insulin-action via Randle's effect in insulin-sensitive tissues. OBJECTIVES In this review, limitations of this paradigm will be discussed and two other paradigms that may explain established links between adiposity and insulin resistance/diabetes will be presented. (A) Ectopic fat storage syndrome. Three lines of evidence support this concept. Firstly, failure to develop adequate adipose tissue mass (also known as 'lipodystrophy') results in severe insulin resistance and diabetes. This is thought to be the result of ectopic storage of lipid into liver, skeletal muscle and the pancreatic insulin-secreting beta cell. Secondly, most obese patients also shunt lipid into the skeletal muscle, the liver and probably the beta cell. The importance of this finding is exemplified by several studies demonstrating that the degree of lipid infiltration into skeletal muscle and liver highly correlates with insulin resistance. Thirdly, increased fat cell size is highly associated with insulin resistance and the development of diabetes. Increased fat cell size may represent the failure of the adipose tissue mass to expand and therefore to accommodate an increased energy influx. Taken together, these observations support the 'acquired lipodystrophy' hypothesis as a link between adiposity and insulin resistance. Ectopic fat deposition is therefore the result of additive or synergistic effects including increased dietary intake, decreased fat oxidation and impaired adipogenesis. (B) Endocrine paradigm. This concept was developed in parallel with the 'ectopic fat storage syndrome' hypothesis. Adipose tissue secretes a variety of endocrine hormones such as leptin, interleukin-6, angiotensin II, adiponectin and resistin. From this viewpoint, adipose tissue plays a critical role as an endocrine gland, secreting numerous factors with potent effects on the metabolism of distant tissues. CONCLUSIONS The novel paradigms of ectopic fat and fat cell as an endocrine organ probably will constitute a new framework for the study of the links between our obesigenic environment and the risk of developing diabetes.
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Affiliation(s)
- L Heilbronn
- Pennington Biomedical Research Center, Baton Rouge, LA, USA
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27
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Walder K, Kerr-Bayles L, Civitarese A, Jowett J, Curran J, Elliott K, Trevaskis J, Bishara N, Zimmet P, Mandarino L, Ravussin E, Blangero J, Kissebah A, Collier GR. The mitochondrial rhomboid protease PSARL is a new candidate gene for type 2 diabetes. Diabetologia 2005; 48:459-68. [PMID: 15729572 DOI: 10.1007/s00125-005-1675-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 10/04/2004] [Indexed: 01/06/2023]
Abstract
AIMS/HYPOTHESIS This study aimed to identify genes that are expressed in skeletal muscle, encode proteins with functional significance in mitochondria, and are associated with type 2 diabetes. METHODS We screened for differentially expressed genes in skeletal muscle of Psammomys obesus (Israeli sand rats), and prioritised these on the basis of genomic localisation and bioinformatics analysis for proteins with likely mitochondrial functions. RESULTS We identified a mitochondrial intramembrane protease, known as presenilins-associated rhomboid-like protein (PSARL) that is associated with insulin resistance and type 2 diabetes. Expression of PSARL was reduced in skeletal muscle of diabetic Psammomys obesus, and restored after exercise training to successfully treat the diabetes. PSARL gene expression in human skeletal muscle was correlated with insulin sensitivity as assessed by glucose disposal during a hyperinsulinaemic-euglycaemic clamp. In 1,031 human subjects, an amino acid substitution (Leu262Val) in PSARL was associated with increased plasma insulin concentration, a key risk factor for diabetes. Furthermore, this variant interacted strongly with age to affect insulin levels, accounting for 5% of the variation in plasma insulin in elderly subjects. CONCLUSIONS/INTERPRETATION Variation in PSARL sequence and/or expression may be an important new risk factor for type 2 diabetes and other components of the metabolic syndrome.
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Affiliation(s)
- K Walder
- Metabolic Research Unit, School of Health Sciences, Deakin University, Pigdons Road, Waurn Ponds, 3217, Australia
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28
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Civitarese AE, Jenkinson CP, Richardson D, Bajaj M, Cusi K, Kashyap S, Berria R, Belfort R, DeFronzo RA, Mandarino LJ, Ravussin E. Adiponectin receptors gene expression and insulin sensitivity in non-diabetic Mexican Americans with or without a family history of Type 2 diabetes. Diabetologia 2004; 47:816-20. [PMID: 15105989 DOI: 10.1007/s00125-004-1359-x] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2003] [Accepted: 01/09/2004] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS The recent discovery of two adiponectin receptors (AdipoR1 and AdipoR2) will improve our understanding of the molecular mechanisms underlying the insulin-sensitising effect of adiponectin. The aim of this study was to determine for the first time whether skeletal muscle AdipoR1 and/or AdipoR2 gene expression levels are associated with insulin resistance. METHODS Using RT-PCR and northern analysis we measured AdipoR1 and AdipoR2 gene expression in skeletal muscle from healthy Mexican Americans with normal glucose tolerance who had (n=8) or did not have (n=10) a family history of Type 2 diabetes. RESULTS Gene expression profiling indicated that the AdipoR1 and AdipoR2 isoforms are highly expressed in human skeletal muscle, unlike in mice where AdipoR2 expression was highest in the liver, and AdipoR1 was highest in skeletal muscle. In the study subjects, the expression levels of AdipoR1 (p=0.004) and AdipoR2 (p=0.04), as well as plasma adiponectin concentration (p=0.03) were lower in people with a family history of Type 2 diabetes than in those with no family history of the disease. Importantly, the expression levels of both receptors correlated positively with insulin sensitivity (r=0.64, p=0.004 and r=0.47, p=0.048 respectively). CONCLUSIONS/INTERPRETATION Collectively, these data indicate that both isoforms of the adiponectin receptor play a role in the insulin-sensitising effect of adiponectin.
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Affiliation(s)
- A E Civitarese
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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29
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Heilbronn LK, Rood J, Janderova L, Albu JB, Kelley DE, Ravussin E, Smith SR. Relationship between serum resistin concentrations and insulin resistance in nonobese, obese, and obese diabetic subjects. J Clin Endocrinol Metab 2004; 89:1844-8. [PMID: 15070954 DOI: 10.1210/jc.2003-031410] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Early reports suggested that resistin is associated with obesity and insulin resistance in rodents. However, subsequent studies have not supported these findings. To our knowledge, the present study is the first assessment in human subjects of serum resistin and insulin sensitivity by the insulin clamp technique. Thirty-eight nonobese subjects [age, 23 +/- 4 yr; body mass index (BMI), 25.4 +/- 4.3 kg/m(2)], 12 obese subjects (age, 54 +/- 8 yr; BMI, 33.0 +/- 2.5 kg/m(2)), and 22 obese subjects with type 2 diabetes (age, 59 +/- 7 yr; BMI, 34.0 +/- 2.4 kg/m(2)) were studied. Serum resistin concentrations were not different among nonobese (4.1 +/- 1.7 ng/ml), obese (4.2 +/- 1.6 ng/ml), and obese diabetic subjects (3.7 +/- 1.2 ng/ml), and were not significantly correlated to glucose disposal rate during a hyperinsulinemic glucose clamp across groups. Serum resistin was, however, inversely related to insulin sensitivity in nonobese subjects only (r = -0.35; P = 0.05), although this association was lost after adjusting for percent body fat. Serum resistin was not related to percent fat, BMI, or fat cell size. A strong correlation was observed between serum resistin and resistin mRNA expression from abdominal sc adipose tissue in a separate group of obese subjects (r = 0.62; P < 0.01; n = 56). Although the exact function of resistin is unknown, we demonstrated only a weak relationship between resistin and insulin sensitivity in nonobese subjects, indicating that resistin is unlikely to be a major link between obesity and insulin resistance in humans.
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Affiliation(s)
- L K Heilbronn
- Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA
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Tataranni PA, Harper IT, Snitker S, Del Parigi A, Vozarova B, Bunt J, Bogardus C, Ravussin E. Body weight gain in free-living Pima Indians: effect of energy intake vs expenditure. Int J Obes (Lond) 2003; 27:1578-83. [PMID: 12975636 DOI: 10.1038/sj.ijo.0802469] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Obesity results from a chronic imbalance between energy intake and energy expenditure. However, experimental evidence of the relative contribution of interindividual differences in energy intake and expenditure (resting or due to physical activity) to weight gain is limited. OBJECTIVE To assess prospectively the association between baseline measurements of daily energy metabolism and weight changes by studying free-living adult Pima Indians, one of the most obese populations in the world. DESIGN A study of the pathogenesis of obesity in the Pima Indians living in Southwestern Arizona. The participants were 92 nondiabetic Pima Indians (64M/28F, 35+/-12 y, 35+/-9% body fat; mean+/-s.d.). At baseline, free-living daily energy metabolism was assessed by doubly labeled water and resting metabolic rate (RMR) by indirect calorimetry. Data on changes in body weight (5.8+/-6.5 kg) over a follow-up period of 4+/-3 y were available in 74 (49M/25F) of the 92 subjects. RESULTS The baseline calculated total energy intake (r=0.25, P=0.028) and RMR (r=-0.28, P=0.016) were significantly associated with changes in body weight. The baseline energy expenditure due to physical activity was not associated with changes in body weight. CONCLUSION Using state-of-the-art methods to assess energy intake and expenditure in free-living conditions, we show for the first time that the baseline calculated total energy intake is a determinant of changes in body weight in Pima Indians. These data also confirm that a low RMR is a risk factor for weight gain in this population.
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Affiliation(s)
- P A Tataranni
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Department of Health and Human Services,Phoenix, AZ 85016, USA.
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Abstract
Adiponectin is an insulin-sensitizing hormone whose blood concentration is reduced in obesity and type 2 diabetes. Administration of recombinant adiponectin in rodents increases glucose uptake and increases fat oxidation in muscle, reduces fatty acid uptake and hepatic glucose production in liver, and improves whole body insulin resistance. The exact receptor and signaling systems are unknown, however, recent studies suggest adiponectin activates AMPK, a putative master metabolic regulator. Thus, excitement surrounds the potential for adiponectin, or a homologue of adiponectin, as pharamacotherapy agents for patients suffering from the metabolic syndrome and more particularly for individuals with insulin resistance and type 2 diabetes.
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Affiliation(s)
- L K Heilbronn
- Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA
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Stefan N, Vozarova B, Del Parigi A, Ossowski V, Thompson DB, Hanson RL, Ravussin E, Tataranni PA. The Gln223Arg polymorphism of the leptin receptor in Pima Indians: influence on energy expenditure, physical activity and lipid metabolism. Int J Obes (Lond) 2002; 26:1629-32. [PMID: 12461680 DOI: 10.1038/sj.ijo.0802161] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2002] [Accepted: 06/19/2002] [Indexed: 12/21/2022]
Abstract
Leptin regulates body weight by its receptor-mediated anorectic, thermogenic and antisteatotic effects. Recently, lower leptin binding to the soluble form of the leptin receptor (LEPR) was shown in carriers of the Arg223-encoding allele of the Gln223Arg polymorphism of the LEPR. To investigate whether this variant influences energy metabolism and adiposity in Pima Indians, we genotyped non-diabetic Pima Indians in whom we had measured body composition and 24 h energy expenditure (24 h EE), physical activity level (PAL) and 24 h respiratory quotient (24 h RQ) in a respiratory chamber (n=268) and who had undergone percutaneous fat biopsies from the periumbilical region (n=184). Genotype was not associated with percent body fat (P>0.39), but was associated with 24 h EE, PAL and mean subcutaneous abdominal adipocyte size (SAAS all P<0.05). Homozygotes for the Arg223-encoding allele had lower 24 h EE (P=0.04) and PAL (P=0.007), but larger SAAS (P=0.01) than Gln homozygotes. These findings are consistent with a role of the Gln223Arg polymorphism in reducing peripheral and central leptin binding to the LEPR in humans. However, these effects do not seem to have a major impact on adiposity in this population.
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Affiliation(s)
- N Stefan
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA.
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Vozarova B, Weyer C, Bogardus C, Ravussin E, Tataranni PA. Differences in oral temperature and body shape in two populations with different propensities for obesity. Ann N Y Acad Sci 2002; 967:516-21. [PMID: 12079882 DOI: 10.1111/j.1749-6632.2002.tb04310.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Body temperature is a function of heat production and heat dissipation. Substantial interindividual variability has been reported in healthy humans. We hypothesized that Pima Indians, a population with a high prevalence of abdominal obesity, may have a lower surface area relative to volume, that is, lower radiating area, and therefore a higher body temperature compared to Caucasians. METHODS Body composition, including volume (hydrodensitometry), and oral temperature were assessed in 69 nondiabetic Caucasian [age, 30 +/- 7 years; body fat, 21 +/- 8% (mean +/- SD)] and 115 Pima Indian males [age, 27 +/- 6 years; body fat, 28 +/- 6%]. Surface area was estimated from height, weight, and waist circumference (Bouchard's equation). In 47 Pima Indians, measures of insulin sensitivity (M, hyperinsulinemic euglycemic clamp) were available. RESULTS Compared to Caucasians, Pima Indians had a higher oral temperature [36.4 +/- 0.3 degrees C vs. 36.3 +/- 0.3 degrees C (mean +/- SD), p < 0.04] and lower surface area relative to volume (2.19 +/- 0.05 vs. 2.23 +/- 0.26 m(2), p < 0.0001). Surface area relative to volume was negatively correlated with oral temperature (r = -0.14, p < 0.05), but in a multiple linear regression model it did not entirely explain the ethnic difference in oral temperature. Oral temperature was inversely correlated with M (r = -0.28, p < 0.05). Conclusions-Pima Indians have higher oral temperature and lower surface area relative to volume than Caucasians. The ethnic difference in temperature does not seem to be entirely explained by differences in body composition and body shape. Interestingly, higher oral temperature was associated with insulin resistance, a risk factor for type 2 diabetes.
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Affiliation(s)
- B Vozarova
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA.
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Abstract
A summary of the Fourth International Smolenice Symposium on Lipids and Insulin Resistance focusing on "The Role of Fatty Acid Metabolism and Fuel Partitioning" is provided. Highlights and issues of the conference are mentioned, as well as strategies for the future.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, Department of Health and Performance Enhancement, Baton Rouge, Louisiana 70808-4124, USA.
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Ravussin E, Gautier JF. [Determinants and control of energy expenditure]. Ann Endocrinol (Paris) 2002; 63:96-105. [PMID: 11994669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Obesity is a risk factor for many diseases including cardio-vascular disease, type 2 diabetes, and certain forms of cancer, among others. Obesity results from a chronic imbalance between calorie intake and energy expenditure. Genetic factors obviously play an important role in weight gain, but only in certain environments. The principal cause of the obesity epidemic is not clear: is obesity due to excessive food intake, a dynamic reduction in energy expenditure, or an association of these two factors? However, most obese subjects gain weight because of an inaptitude to adjust energy expenditure in response to excessive food intake. In this article, we review briefly the respective role of genes and environment in the development of obesity, then describe metabolic risk factors involved. Longitudinal studies conducted in Pima Indians have demonstrated that a relative decrease in basal metabolism, weak lipid oxidation in the fasting state, reduced spontaneous physical activity, and lower sympathetic nervous system activity are risk factors for obesity. Unlike our growing knowledge of food intake regulation, little is known about the control of energy expenditure. New discoveries should provide information on obesity susceptibility genes and increase the chances of developing new anti-obesity treatments.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, 6400 Perkins Road Baton Rouge, LA 70804-4124, USA
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Rohner-Jeanrenaud F, Craft LS, Bridwell J, Suter TM, Tinsley FC, Smiley DL, Burkhart DR, Statnick MA, Heiman ML, Ravussin E, Caro JF. Chronic central infusion of cocaine- and amphetamine-regulated transcript (CART 55-102): effects on body weight homeostasis in lean and high-fat-fed obese rats. Int J Obes (Lond) 2002; 26:143-9. [PMID: 11850744 DOI: 10.1038/sj.ijo.0801863] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2001] [Revised: 07/05/2001] [Accepted: 07/30/2001] [Indexed: 11/09/2022]
Abstract
BACKGROUND Cocaine- and amphetamine-regulated transcript (CART) is expressed within hypothalamic nuclei implicated in the regulation of feeding behaviour. It is up-regulated by leptin, and CART-derived peptides acutely inhibit food intake. OBJECTIVE The present study was designed to assess the long-term effects of central CART administration on food intake, body weight, plasma levels of glucose, insulin, leptin, free fatty acids and triglycerides, and on fuel utilisation in normal and high-fat-fed obese rats. DESIGN Normal and high-fat-fed obese rats were cannulated intracerebroventricularly (i.c.v.) and infused for 6 days with CART (55-102) or its vehicle. At day 4, animals were placed in an indirect calorimeter for a 24 h period during which the respiratory quotient and the energy expenditure were determined hourly. RESULTS In both normal and obese animals, the chronic i.c.v. infusion of CART (55-102) had marked, sustained inhibitory effects on food intake and body weight gain that were accompanied by decreases in plasma insulin and leptin levels. Using indirect calorimetry, it was observed that CART infusion promoted an increase in lipid oxidation in normal and in obese animals, although this increase reached statistical significance only in the obese group. The hypothalamic CART mRNA expression was found to be higher in obese rats (displaying hyperleptinaemia) than in normal animals. CONCLUSION The data together show that chronic i.c.v. CART infusion is effective in inhibiting food intake, favouring lipid oxidation and limiting fat storage, both in normal and high-fat-diet-induced obese rats. The CART pathway thus seems to be an important determinant of body weight homeostasis in normal animals as well as in a model of nutritionally induced obesity.
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Affiliation(s)
- F Rohner-Jeanrenaud
- Endocrine Research and Clinical Investigation, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA.
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Weyer C, Vozarova B, Ravussin E, Tataranni PA. Changes in energy metabolism in response to 48 h of overfeeding and fasting in Caucasians and Pima Indians. Int J Obes (Lond) 2001; 25:593-600. [PMID: 11360139 DOI: 10.1038/sj.ijo.0801610] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2000] [Revised: 11/10/2000] [Accepted: 01/03/2000] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Differences in the metabolic response to overfeeding and starvation may confer susceptibility or resistance to obesity in humans. To further examine this hypothesis, we assessed the changes in 24 h energy metabolism in response to short-term overfeeding and fasting in Caucasians (C) and Pima Indians (I), a population with a very high propensity for obesity. METHODS We measured the changes in 24 h energy expenditure (24 -EE) and 24 h respiratory quotient (24-RQ) in response to 48 h of mixed diet overfeeding (100% above energy requirements) and fasting in a whole body respiratory chamber in 14 male subjects (7 C/7 I, age 30+/-6 y, mean+/-s.d.). Results were compared to a 24 h measurement under eucaloric conditions. RESULTS Mean 24-EE increased in response to overfeeding and decreased in response to fasting (all changes P<0.01), with no differences between C (+9.1% and -9.1%) and I (+8.6% and -9.6%). Similarly, mean 24-RQ increased/decreased in response to overfeeding/fasting, respectively (all changes P<0.01), again with no differences between C (+0.06 and -0.05) and I (+0.05 and -0.05). The changes in 24-EE in response to overfeeding and fasting were positively correlated (r=0.70, P<0.01), whereas those in 24-RQ were not (r=0.40, NS). CONCLUSIONS Pima Indians do not appear to have an impaired metabolic response to short-term overfeeding and fasting that could explain their propensity for obesity. Individuals with a large increase in energy expenditure in response to overfeeding appear to have a small decrease in energy expenditure in response to starvation (spendthrift phenotype) and vice versa (thrifty phenotype).
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Affiliation(s)
- C Weyer
- Clinical Diabetes and Nutrition Section, NIDDK, National Institutes of Health, Phoenix, Arizona 85016, USA.
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Gautier JF, Del Parigi A, Chen K, Salbe AD, Bandy D, Pratley RE, Ravussin E, Reiman EM, Tataranni PA. Effect of satiation on brain activity in obese and lean women. Obes Res 2001; 9:676-84. [PMID: 11707534 DOI: 10.1038/oby.2001.92] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To investigate the response of the brains of women to the ingestion of a meal. RESEARCH METHODS AND PROCEDURES We used measures of regional cerebral blood flow (rCBF), a marker of neuronal activity, by positron emission tomography to describe the functional anatomy of satiation, i.e., the response to a liquid meal in the context of extreme hunger (36-hour fast) in 10 lean (BMI < or = 25 kg/m(2); 32 +/- 10 years old, 61 +/- 7 kg; mean +/- SD) and 12 obese (BMI > or = 35 kg/m(2); 30 +/- 7 years old, 110 +/- 14 kg) women. RESULTS In lean and obese women, satiation produced significant increases in rCBF in the vicinity of the prefrontal cortex (p < 0.005). Satiation also produced significant decreases in rCBF in several regions including the thalamus, insular cortex, parahippocampal gyrus, temporal cortex, and cerebellum (in lean and obese women), and hypothalamus, cingulate, nucleus accumbens, and amygdala (in obese women only; all p < 0.005). Compared with lean women, obese women had significantly greater increases in rCBF in the ventral prefrontal cortex and had significantly greater decreases in the paralimbic areas and in areas of the frontal and temporal cortex. DISCUSSION This study indicates that satiation elicits differential brain responses in obese and lean women. It also lends additional support to the hypothesis that the paralimbic areas participate in a central orexigenic network modulated by the prefrontal cortex through feedback loops.
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Affiliation(s)
- J F Gautier
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA
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Ravussin E, Gautier JF. [Control of energy expenditure]. Journ Annu Diabetol Hotel Dieu 2001:97-112. [PMID: 11565473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA
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Snitker S, Tataranni PA, Ravussin E. Spontaneous physical activity in a respiratory chamber is correlated to habitual physical activity. Int J Obes (Lond) 2001; 25:1481-6. [PMID: 11673770 DOI: 10.1038/sj.ijo.0801746] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2001] [Revised: 03/30/2001] [Accepted: 04/02/2001] [Indexed: 11/09/2022]
Abstract
OBJECTIVE During a stay in a respiratory chamber without an exercise protocol, physical activity is limited to activities of daily living, change of posture and 'fidgeting,' collectively referred to as spontaneous physical activity (SPA). SPA is quite variable among individuals and is a heritable trait. A low SPA during a chamber stay is a predictor of weight gain in men. However, it remains to be established whether physical activity in a respiratory chamber relates to physical activity under habitual, free-living conditions. The purpose of the present study was to determine whether physical activity in a chamber is correlated to habitual, free-living physical activity. DESIGN Fifty healthy, non-diabetic Pima Indians (30 M/20 F, 30+/-6 y; 37+/-10% body fat; means+/-s.d.) completed a 24 h stay in the respiratory chamber followed by a 7 day measurement of habitual, free-living energy expenditure by doubly labeled water. Free-living physical activity was expressed as activity energy expenditure (AEE(FL); daily energy expenditure-(sleeping metabolic rate+thermic effect of food)), physical activity level (PAL(FL); daily energy expenditure/sleeping metabolic rate) and body-size independent activity units. Activity during the chamber stay was expressed as PAL(Ch), AEE(Ch), and based on radar sensor measurements, as percentage of time with activity (SPA(Radar)). RESULTS AEE(FL) (averaging 930+/-310 kcal/day (3.89+/-1.30 MJ/day)) was correlated to AEE(CH) (averaging 440+/-160 kcal/day (1.84+/-0.67 MJ/day)) and higher in men than in women (r=0.53, P=0.003) and r=0.53, P=0.02, respectively). Likewise, PAL(FL) (averaging 1.75+/-0.21) was correlated to PAL(Ch) (averaging 1.42+/-0.10) and higher in men than in women (r=0.49, P=0.006 and r=0.42, P=0.02, respectively). Free-living activity expressed in body-size independent activity units (averaging 17.8+/-7.0) was correlated to SPA(Radar) (averaging 6.4+/-1.7) with no effect of sex (r=0.30, P=0.03). CONCLUSION Physical activity in a respiratory chamber was correlated to habitual physical activity, whether expressed as AEE, PAL or body-size independent activity units, providing a plausible explanation for the demonstrated association between a low SPA in the chamber and weight gain. The study encourages further studies of the genetic and non-genetic determinants of SPA and non-exercise activity thermogenesis (NEAT).
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Affiliation(s)
- S Snitker
- University of Maryland School of Medicine, Division of Endocrinology, Diabetes and Nutrition, Baltimore, Maryland 21201, USA.
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Ravussin E, Tschöp M, Morales S, Bouchard C, Heiman ML. Plasma ghrelin concentration and energy balance: overfeeding and negative energy balance studies in twins. J Clin Endocrinol Metab 2001; 86:4547-51. [PMID: 11549706 DOI: 10.1210/jcem.86.9.8003] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Central (intracerebral ventral) and peripheral (subcutaneous and intraperitoneal) administration of ghrelin causes obesity in rodents by increasing food intake and decreasing fat oxidation. Recent studies in humans have shown that plasma ghrelin concentration was inversely related to body fat and was lower in Pima Indians, a population susceptible to obesity. Whether ghrelin plays a role in the etiology of obesity in humans is unknown. We, therefore, measured plasma ghrelin concentration before and after two interventions in monozygotic twins previously studied at Laval University, Quebec City. Twelve pairs of monozygotic twins were overfed by 84,000 kcal over a 100-day period, whereas another seven pairs of monozygotic twins were submitted to a 53,000 kcal negative energy balance induced by exercise over a 93-day period. At baseline, for all the subjects, plasma ghrelin concentration was negatively correlated with body mass and body fatness (r varying from 0.36 to 0.45). The intraclass coefficient for the twin resemblance (r(I) = 0.75; p = 0.006) indicated that plasma ghrelin concentration is a familial trait. In response to the 100-day intervention, plasma ghrelin exhibited a non-significant decrease of 61 +/- 30 fmol/l (p = 0.18) with overfeeding and a non-significant increase of 58 +/- 34 fmol/l (p = 0.17) with negative energy balance. However, there was no relationship between baseline plasma ghrelin concentration and the magnitude of body weight change in both interventions. These first experimental data under "clamped energy balance conditions" do not provide evidence that plasma ghrelin is involved in the etiology of human obesity. However, studies in free-living individuals are needed to clarify this question.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
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Lindsay RS, Hanson RL, Roumain J, Ravussin E, Knowler WC, Tataranni PA. Body mass index as a measure of adiposity in children and adolescents: relationship to adiposity by dual energy x-ray absorptiometry and to cardiovascular risk factors. J Clin Endocrinol Metab 2001; 86:4061-7. [PMID: 11549626 DOI: 10.1210/jcem.86.9.7760] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Body mass index is widely used as a measure of adiposity in adults, but its use in children and adolescents is controversial. We assessed body mass index as a measure of adiposity in children and adolescents between the ages of 5 and 20 yr examined as part of the NIH survey of health in the Pima Indian population. Body mass index (measured in 985 subjects and analyzed in 3 age groups: 5-9, 10-14, and 15-19 yr, in both sexes) was compared cross-sectionally to percent fat and fat mass derived from dual energy x-ray absorptiometry and to fasting and 2-h plasma glucose, systolic and diastolic blood pressures, cholesterol, high density lipoprotein cholesterol, fasting insulin, and triglycerides. Body mass index was strongly correlated in all age groups to both percent fat (r = 0.83-0.94; for each group, P < 0.0001) and fat mass (r = 0.96-0.98; P < 0.0001). The relationship of body mass index to percent fat was different in males and females; differences were more marked in older age groups. Body mass index, percent fat, and fat mass showed similar degrees of correlation to metabolic measures in childhood. Body mass index is strongly associated with measures of adiposity derived from dual energy x-ray absorptiometry. Both measures show similar associations with cardiovascular risk factors in Pima Indian children.
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Affiliation(s)
- R S Lindsay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85014, USA.
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Ukkola O, Ravussin E, Jacobson P, Snyder EE, Chagnon M, Sjöström L, Bouchard C. Mutations in the preproghrelin/ghrelin gene associated with obesity in humans. J Clin Endocrinol Metab 2001; 86:3996-9. [PMID: 11502844 DOI: 10.1210/jcem.86.8.7914] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ghrelin and preproghrelin sequences were determined in 96 unrelated female subjects with severe obesity (mean body mass index (BMI) 42.3 +/- 3.4 kg/m(2)) and in 96 non-obese female controls (mean BMI 23.0 +/- 1.4 (kg/m2) of the Swedish Obese Subjects cohort. A mutation at amino acid position 51 (Arg51Gln) of the preproghrelin sequence that corresponds to the last amino acid in mature ghrelin product was identified in six (all heterozygotes) obese subjects (6.3%) but not among controls (p < 0.05). The self-reported weight at 20, 30, and 40 years of age tended to be 7.5, 4.7 and 6.4 kg lower, respectively, among obese Gln allele carriers versus obese non-carriers. In addition, a mutation at codon 72 of the preproghrelin gene (Leu72Met) was detected in 15 obese (12 hetero- and 3 homozygotes) and 12 control (all heterozygotes) subjects. This mutation outside the coding region of the mature ghrelin product tended to be associated with lower age of self-reported onset of obesity (15.6 +/- 7.9 vs. 20.5 +/- 10.5 years; p = 0.09). In addition to these two mutations in coding regions, a G274A base change in a non-coding region between exons one and two was found only in two obese individuals. The Arg51Gln amino acid substitution may alter the cleavage site of endoproteases and the length of the mature ghrelin product. The functional significance of the Leu72Met mutation and a G274A base change remains to be determined. In conclusion, the data provide evidence that a low frequency sequence variation in the ghrelin gene could play a role in the etiology of obesity.
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Affiliation(s)
- O Ukkola
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
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Abstract
Ghrelin is a novel endogenous natural ligand for the growth hormone (GH) secretagogue receptor that has recently been isolated from the rat stomach. Ghrelin administration stimulates GH secretion but also causes weight gain by increasing food intake and reducing fat utilization in rodents. To investigate the possible involvement of ghrelin in the pathogenesis of human obesity, we measured body composition (by dual X-ray absorption) as well as fasting plasma ghrelin concentrations (radioimmunoassay) in 15 Caucasians (8 men and 7 women, 31+/-9 years of age, 92+/-24 kg body wt, and 29+/-10% body fat, mean +/- SD) and 15 Pima Indians (8 men and 7 women, 33+/-5 years of age, 97+/-29 kg body wt, and 30+/-8% body fat). Fasting plasma ghrelin was negatively correlated with percent body fat (r = -0.45; P = 0.01), fasting insulin (r = -0.45; P = 0.01) and leptin (r = -0.38; P = 0.03) concentrations. Plasma ghrelin concentration was decreased in obese Caucasians as compared with lean Caucasians (P < 0.01). Also, fasting plasma ghrelin was lower in Pima Indians, a population with a very high prevalence of obesity, compared with Caucasians (87+/-28 vs. 129+/-34 fmol/ml; P < 0.01). This result did not change after adjustment for fasting plasma insulin concentration. There was no correlation between fasting plasma ghrelin and height. Prospective clinical studies are now needed to establish the role of ghrelin in the pathogenesis of human obesity.
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Affiliation(s)
- M Tschöp
- Endocrine Research Department, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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Guesbeck NR, Hickey MS, MacDonald KG, Pories WJ, Harper I, Ravussin E, Dohm GL, Houmard JA. Substrate utilization during exercise in formerly morbidly obese women. J Appl Physiol (1985) 2001; 90:1007-12. [PMID: 11181612 DOI: 10.1152/jappl.2001.90.3.1007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to compare substrate utilization during fasting and submaximal exercise in morbidly obese women after weight loss (WL) with that in weight-matched controls (C). WL were studied in the weight-stable condition approximately 24 mo after gastric bypass surgery. Energy intake (self-reported) and expenditure ((2)H(2)(18)O) were also compared. The respiratory exchange ratio during exercise at the same absolute (15 W) workload was significantly (P < or = 0.05) elevated in WL vs. C (0.90 +/- 0.02 vs. 0.83 +/- 0.03); this was reflected as lower fat utilization in WL (29.7 +/- 4.8 vs. 53.2 +/- 9.7% of energy from fat). Respiratory exchange ratio during exercise at the same relative (65% of maximal O(2) uptake) intensity was also significantly (P < 0.05) elevated in WL (0.96 +/- 0.01 vs. 0.89 +/- 0.02), and fat use was concomitantly depressed (12.4 +/- 3.0 vs. 34.3 +/- 9.9% of energy from fat). Resting substrate utilization, daily energy expenditure, and self-reported relative macronutrient intake did not differ between groups. These data suggest that lipid oxidation is depressed during physical activity in WL. This defect may, at least in part, contribute to a propensity for the development of morbid obesity.
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Affiliation(s)
- N R Guesbeck
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina 27858, USA
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Abstract
The increasing prevalence of obesity worldwide has prompted the World Health Organization (WHO) to classify it as a global epidemic. Around the globe, more than a half billion people are overweight, and the chronic disease of obesity represents a major threat to health care systems in developed and developing countries. The major health hazards associated with obesity are the risks of developing diabetes, cardiovascular disease, stroke, osteoarthritis and some forms of cancer. In this paper, we review the prevalence of obesity and its cost to health care systems and present the relative contribution of environmental conditions and genetic makeup to the development of obesity in people. We also discuss the concept of "essential" obesity in an "obesigenic" environment. Though weight gain results from a sustained imbalance between energy intake and energy expenditure, it is only recently that studies have identified important new mechanisms involved in the regulation of body weight. The etiology of the disease is presented as a feedback model in which afferent signals inform the central controllers in the brain as to the state of the external and internal environment and elicit responses related to the regulation of food intake and energy metabolism. Pharmaceutical agents may intervene at different levels of this feedback model, i.e., reinforce the afferent signals from the periphery, target the central pathways involved in the regulation of food intake and energy expenditure, and increase peripheral energy expenditure and fat oxidation directly. Since obesity results from genetic predisposition, combined with the proactive environmental situation, we discuss new potential targets for generation of drugs that may assist people in gaining control over appetite as well as increasing total energy expenditure and fat oxidation.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808-4124, USA.
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Pratley RE, Baier L, Pan DA, Salbe AD, Storlien L, Ravussin E, Bogardus C. Effects of an Ala54Thr polymorphism in the intestinal fatty acid-binding protein on responses to dietary fat in humans. J Lipid Res 2000; 41:2002-8. [PMID: 11108733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
A polymorphism in FABP2 that results in an alanine-to-threonine substitution at amino acid 54 of the intestinal fatty acid-binding protein (IFABP) is associated with insulin resistance in Pima Indians. In vitro, the threonine form (Thr54) has a higher binding affinity for long-chain fatty acids than does the alanine form (Ala54). We tested whether this polymorphism affected metabolic responses to dietary fat, in vivo. Eighteen healthy Pima Indians, half homozygous for the Thr54 form of IFABP and half homozygous for the Ala54 form, were studied. The groups were matched for sex, age, and body mass index. Plasma triglyceride, nonesterified fatty acid (NEFA), glucose, and insulin responses were measured after a mixed meal (35% of daily energy requirements, 50 g of fat) and after a high fat challenge (1362 kcal, 129 g of fat). NEFA concentrations were approximately 15% higher after the mixed meal and peaked earlier and were approximately 20% higher at 7 h in response to the high fat test meal in Thr54 homozygotes compared with Ala54 homozygotes. Insulin responses to the test meals tended to be higher in Thr54 homozygotes, but glucose and triglyceride responses were not different.The results of this study suggest that the Thr54 form of IFABP is associated with higher and prolonged NEFA responses to dietary fat in vivo. Higher NEFA concentrations may contribute to insulin resistance and hyperinsulinemia in individuals with this allele.
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Affiliation(s)
- R E Pratley
- Clinical Diabetes and Nutrition Section, Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85016, USA
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Weyer C, Pratley RE, Snitker S, Spraul M, Ravussin E, Tataranni PA. Ethnic differences in insulinemia and sympathetic tone as links between obesity and blood pressure. Hypertension 2000; 36:531-7. [PMID: 11040231 DOI: 10.1161/01.hyp.36.4.531] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hyperinsulinemia and increased sympathetic nervous system (SNS) activity are thought to be pathophysiological links between obesity and hypertension. In the present study, we examined the relation among heart rate (HR), blood pressure (BP), and percent body fat (hydrodensitometry or DEXA), fasting plasma insulin concentration, and muscle sympathetic nerve activity (MSNA, microneurography) in male, normotensive whites (n=42) and Pima Indians (n=77). Pima Indians have a high prevalence of obesity and hyperinsulinemia but a relatively low prevalence of hypertension. Compared with whites, Pima Indian men had a higher percent body fat (28% versus 21%) and higher fasting insulin concentrations (210 versus 132 pmol/L) but lower MSNA (27 versus 33 bursts/min) (all P<0.001). In both ethnic groups, HR and BP were positively related to percent body fat and MSNA, and both were significant independent determinants of HR and BP in multiple regression analyses. However, MSNA was positively related to percent body fat and the fasting insulin concentration in whites (r=0.60 and r=0.47, both P<0.01) but not in Pima Indians (r=0.15 and r=0.03, NS) (P<0.01 for ethnic differences in the slope of the regression lines). These results confirm the physiological importance of the SNS in normal BP regulation but indicate that the roles of hyperinsulinemia and increased SNS activity as mediators for the relation between obesity and hypertension can differ between different ethnic groups. The lack of an increase in SNS activity with increasing adiposity and insulinemia in Pima Indians may contribute to the low prevalence of hypertension in this population.
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Affiliation(s)
- C Weyer
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, USA.
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Weyer C, Walford RL, Harper IT, Milner M, MacCallum T, Tataranni PA, Ravussin E. Energy metabolism after 2 y of energy restriction: the biosphere 2 experiment. Am J Clin Nutr 2000; 72:946-53. [PMID: 11010936 DOI: 10.1093/ajcn/72.4.946] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND An adaptive decrease in energy expenditure (EE) in response to 6 mo of severely restricted energy intake was shown in a classic semistarvation study-the Minnesota experiment. OBJECTIVE Our objective was to examine whether such adaptation also occurs in response to less severe but sustained energy restriction. DESIGN Body composition, 1-wk total EE (TEE), 24-h sedentary EE, and spontaneous physical activity were measured in 8 healthy subjects (4 men and 4 women) at the end of a 2-y confinement inside Biosphere 2. Unexpectedly, the food supply was markedly restricted during most of the confinement and all subjects experienced a marked, sustained weight loss (9.1 +/- 6.6 kg; P: < 0.001) from the low-energy (7000-11000 kJ/d), low-fat (9% of energy), but nutrient-dense, diet they consumed. RESULTS The TEE inside Biosphere 2, assessed 3 wk before exit, averaged 10700 +/- 560 kJ/d (n = 8). Within 1 wk after exit, the adjusted 24-h EE and spontaneous physical activity were lower in the biospherians (n = 5) than in 152 control subjects (6% and 45%, respectively; both P: < 0.01). Six months after exit and return to an ad libitum diet, body weight had increased to preentry levels; however, adjusted 24-h EE and spontaneous physical activity were still significantly lower than in control subjects. CONCLUSIONS In lean humans, an adaptive decrease in EE appears to occur not only in states of life-threatening undernutrition, but also in response to less severe energy restriction sustained over several years.
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Affiliation(s)
- C Weyer
- Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85106, USA.
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