Preferential loss of visceral fat following aerobic exercise, measured by magnetic resonance imaging

Moderate intensity continuous and interval training affect visceral fat and insulin resistance model in female rat exposed high calorie diet

Chronic high-calorie diet (HCD) combined with physical inactivity promotes obesity and insulin resistance (IR). This study aimed to analyse the comparable effect of moderate-intensity continuous training (MICT) and moderate-intensity interval training (MIIT) on visceral fat weight and IR in subjects exposed to HCD. This randomised post-test research used only a control group design with female rats (Wistar norvegicus), 8 weeks old and 100-200 g of bodyweight. They were randomly divided into four groups: standard diet group (C), HCD group (C1), HCD combined with MICT group (C2) and HCD combined with MIIT group (C3). Each group consisted of six rats. HCD consisted of ad libitum standard diet plus dextrose solution by oral gavage for 4 weeks. The MICT was conducted by swimming plus 6% load of body weight for 10 min in the first week, for 20 min in the second week and 30 min in the third and fourth week. The MIIT was conducted by swimming in a ratio between swimming and rest time at 2:1 plus 6% load of BW, performed 5×/week for 4 weeks, and increased progressively. The mean body weight pre-intervention was 152.79±13.280 g and 150.12±9.195 g post-intervention (P=0.115). The mean fasting blood glucose pre-intervention was 79±8.668 mg/dl, and post-intervention 86.29±12.142 mg/dl (P=0.142). The mean visceral fat weight between C (1.94±0.66 g), C1 (1.45±0.47 g), C2 (1.41±0.44 g), and C3 (1.22±0.59 g) was not significant (P=0.179). The mean triglyceride level for C (173.33±30.30 mg/dl), C1 (157.16±47.32 mg/dl), C2 (112.83±25.49 mg/dl), and C3 (80.33±23.47 mg/dl) was significant (P=0.000). The mean IR model for C (4.796±0.070), C1 (4.728±0.125), C2 (4.620±0.123), C3 (4.360±0.143) was significant (P=0.000). In conclusion, both MICT and MIIT have an effect to improve IR and TG. The MIIT was more effective to improve IR compared to MICT in the female rats exposed to an HCD.

Visceral Adiposity and Cancer: Role in Pathogenesis and Prognosis

The prevalence of being overweight and obese has been expanded dramatically in recent years worldwide. Obesity usually occurs when the energetic introit overtakes energy expenditure from metabolic and physical activity, leading to fat accumulation mainly in the visceral depots. Excessive fat accumulation represents a risk factor for many chronic diseases, including cancer. Adiposity, chronic low-grade inflammation, and hyperinsulinemia are essential factors of obesity that also play a crucial role in tumor onset. In recent years, several strategies have been pointed toward boundary fat accumulation, thus limiting the burden of cancer attributable to obesity. While remodeling fat via adipocytes browning seems a tempting prospect, lifestyle interventions still represent the main pathway to prevent cancer and enhance the efficacy of treatments. Specifically, the Mediterranean Diet stands out as one of the best dietary approaches to curtail visceral adiposity and, therefore, cancer risk. In this Review, the close relationship between obesity and cancer has been investigated, highlighting the biological mechanisms at the basis of this link. Finally, strategies to remodel fat, including browning and lifestyle interventions, have been taken into consideration as a major perspective to limit excess body weight and tumor onset.

Fat mass prediction equations and reference ranges for Saudi Arabian Children aged 8-12 years using machine technique method

Background

The number of children with obesity has increased in Saudi Arabia, which is a significant public health concern. Early diagnosis of childhood obesity and screening of the prevalence is needed using a simple in situ method. This study aims to generate statistical equations to predict body fat percentage (BF%) for Saudi children by employing machine learning technology and to establish gender and age-specific body fat reference range.

Methods

Data was combined from two cross-sectional studies conducted in Saudi Arabia for 1,292 boys and girls aged 8-12 years. Body fat was measured in both studies using bio-electrical impedance analysis devices. Height and weight were measured and body mass index was calculated and classified according to CDC 2,000 charts. A total of 603 girls and 374 boys were randomly selected for the learning phase, and 153 girls and 93 boys were employed in the validation set. Analyses of different machine learning methods showed that an accurate, sensitive model could be created. Two regression models were trained and fitted with the construction samples and validated. Gradient boosting algorithm was employed to achieve a better estimation and produce the equations, then the root means squared error (RMSE) equation was performed to decrease the error. Body fat reference ranges were derived for children aged 8-12 years.

Results

For the gradient boosting models, the predicted fat percentage values were more aligned with the true value than those in regression models. Gradient boosting achieved better performance than the regression equation as it combined multiple simple models into a single composite model to take advantage of that weak classifier. The developed predictive model archived RMSE of 3.12 for girls and 2.48 boys. BF% and Fat mass index charts were presented in which cut-offs for 5th, 75th and 95th centiles are used to define 'under-fat', 'normal', 'overfat' and 'subject with obesity'.

Conclusion

Machine learning models could represent a significant advancement for investigators studying adiposity-related issues in children. These models and newly developed centile charts could be useful tools for the estimation and classification of BF%.

Novel Insights into the Pathogenesis and Management of the Metabolic Syndrome

The metabolic syndrome, by definition, is not a disease but is a clustering of individual metabolic risk factors including abdominal obesity, hyperglycemia, hypertriglyceridemia, hypertension, and low high-density lipoprotein cholesterol levels. These risk factors could dramatically increase the prevalence of type 2 diabetes and cardiovascular disease. The reported prevalence of the metabolic syndrome varies, greatly depending on the definition used, gender, age, socioeconomic status, and the ethnic background of study cohorts. Clinical and epidemiological studies have clearly demonstrated that the metabolic syndrome starts with central obesity. Because the prevalence of obesity has doubly increased worldwide over the past 30 years, the prevalence of the metabolic syndrome has markedly boosted in parallel. Therefore, obesity has been recognized as the leading cause for the metabolic syndrome since it is strongly associated with all metabolic risk factors. High prevalence of the metabolic syndrome is not unique to the USA and Europe and it is also increasing in most Asian countries. Insulin resistance has elucidated most, if not all, of the pathophysiology of the metabolic syndrome because it contributes to hyperglycemia. Furthermore, a major contributor to the development of insulin resistance is an overabundance of circulating fatty acids. Plasma fatty acids are derived mainly from the triglycerides stored in adipose tissues, which are released through the action of the cyclic AMP-dependent enzyme, hormone sensitive lipase. This review summarizes the latest concepts in the definition, pathogenesis, pathophysiology, and diagnosis of the metabolic syndrome, as well as its preventive measures and therapeutic strategies in children and adolescents.

Effect of Exercise and Pharmacological Interventions on Visceral Adiposity: A Systematic Review and Meta-analysis of Long-term Randomized Controlled Trials

OBJECTIVE

To assess the effectiveness of exercise and pharmacotherapy interventions in reducing visceral adipose tissue (VAT).

PATIENTS AND METHODS

A systematic search of Ovid MEDLINE, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov, New York Academy of Science Grey Literature Report, and OpenGrey was combined with hand searches of existing literature. A total of 2515 titles and abstracts were reviewed. Only randomized controlled trials evaluating the effectiveness of monitored exercise or pharmacological interventions in reducing VAT by using computed tomography or magnetic resonance imaging during a sustained intervention period (≥6 months) were included. Data were independently extracted by reviewers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and assessed for quality and risk of bias. Separate analyses for each intervention were performed using random effect models, with pooled estimates of the change in VAT area (in centimeters squared) from baseline to follow-up reported as standardized mean difference (SMD; with 95% CI).

RESULTS

A total of 3602 participants from 17 randomized controlled trials were included in the final analysis. Both exercise and pharmacological interventions were associated with significant reductions in VAT: small reduction with pharmacological interventions (SMD, -0.27; 95% CI, -0.47 to -0.07; P=.02) and more substantial reductions with exercise interventions (SMD, -0.54; 95% CI, -0.63 to -0.46; P<.001). The mean absolute VAT reduction was greater in pharmacological trials than in exercise trials. Meta-regression exhibited a linear correlation between VAT and weight loss (R²=0.52 for exercise and R²=0.88 for pharmacological interventions), but VAT reduction relative to weight loss differed by intervention type.

CONCLUSION

Exercise interventions resulted in greater reduction in VAT relative to weight loss than did pharmacological interventions. A preferential reduction in VAT may be clinically meaningful when monitoring success of interventions because weight loss alone may underestimate benefits.

Exercise training and/or diet on reduction of intra-abdominal adipose tissue and risk factors for cardiovascular disease

BACKGROUND/OBJECTIVES

To test the effects of weight loss with and without exercise training (aerobic or resistance) on intra-abdominal adipose tissue (IAAT) and risk factors for cardiovascular disease (CVD). Additionally, CVD risk factors was evaluated before and after weight loss using previously established IAAT cut-points.

SUBJECTS/METHODS

One hundred twenty-two overweight premenopausal women were randomly assigned to one of three groups: (1) diet only (Diet); (2) diet and aerobic training (Diet + AT); or (3) diet and resistance training (Diet + RT); until a BMI of < 25 kg/m² was reached. Computerized tomography was used to measure IAAT and blood lipids were measured by assay. Evaluations were made before and after weight loss.

RESULTS

Though no group-by-time effects were found after weight loss, we observed significant time effects for: IAAT (-38.0%, P < 0.001), total cholesterol (TC) (-2.2%, P = 0.008), low-density lipoprotein cholesterol (LDL-C) (-4.8%, P < 0.001), high-density lipoprotein cholesterol (HDL-C) (+20.2%, P < 0.001), triglycerides (-18.7%, P < 0.001), TC/HDL-C (-16.3%, P < 0.001), and LDL-C/HDL-C (-18.0%, P < 0.001). Following weight loss, 40.2% of all participants reduced IAAT to < 40 cm² (IAAT associated with low CVD risk). Furthermore, only 2.5% of participants had an IAAT > 110 cm² (IAAT associated with high CVD risk) after weight loss. We also observed that decreases of IAAT were associated with decreased CVD risk factors after weight loss independent of race, changes in %fat mass and changes in maximal oxygen uptake.

CONCLUSIONS

Caloric restriction leading to significant weight loss with or without exercise training appears to be equally effective for reducing IAAT and CVD risk factors.

Visceral Adipose Tissue Accumulation and Residual Cardiovascular Risk

PURPOSE OF THE REVIEW

Low-grade systemic inflammation increases residual cardiovascular risk. The pathogenesis of low-grade systemic inflammation is not well understood.

RECENT FINDINGS

Visceral adipose tissue accumulates when the subcutaneous adipose tissue can no longer store excess nutrients. Visceral adipose tissue inflammation initially facilitates storage of nutrients but with time become maladaptive and responsible for low-grade systemic inflammation. Control of low-grade systemic inflammation requires reversal of visceral adipose tissue accumulation with intense and sustained aerobic exercise or bariatric surgery. Alternatively, pharmacologic inhibition of the inflammatory signaling pathway may be considered. Reversal visceral adipose tissue accumulation lowers residual cardiovascular risk.

Influence of previous body mass index and sex on regional fat changes in a weight loss intervention

OBJECTIVES

Men and women may lose weight in a different fashion. This study compares the changes in different anatomical regions after a well-controlled weight loss program by sex and initial BMI.

METHODS

A total of 180 subjects (48 overweight women, 36 overweight men, and 48 obese women and 48 obese men) were recruited to participate in a 22-week weight loss programme (diet + exercise).

RESULTS

Regarding percentage body weight change from baseline, there was no triple interaction (BMI, sex and anatomical region), but there was interaction between BMI and anatomical region (F2,840 = 34.5; p < 0.001), and between sex and anatomical region (F2,840 = 98.8; p < 0.001). Usually, the arms and legs are the regions that lose more weight in obese participants, but men lose the highest percentage of mass from the trunk. There were differences between men and women for the areas of left trunk mass (750g), right trunk mass (700g), total mass of the trunk (1400g), android mass (350g), and finally in the total mass in overweight participants (1300g), with higher values for men than for women. The region that loses more weight and fat is the trunk, followed by the legs, and then the arms, when the loss is observed in function of the total weight or fat lost.

CONCLUSION

Both BMI and sex exert a definite influence fat loss, especially in some anatomical regions.

The effect of exercises on left ventricular systolic and diastolic heart function in sedentary women: Step-aerobic vs core exercises

The purpose of this study is to investigate the effect of 16 weeks step-aerobic exercises and core exercises on left ventricular structure and function with some physiological parameters in sedentary women.

Methods

To achieve the purpose of this study, a total of 45 volunteers including (step-aerobic group (SAG, n = 25), core exercise group (CEG, n = 20) were selected as participants. Two different exercises were applied for 4 days a week, throughout 16 weeks, within 60 minutes for each exercise with the intensity of heart rate (HR) 60-70 percent. The HR was measured using a heart rate monitor for each subject. The physical, biochemical and echocardiographic characteristics of the women were measured before and after the exercise.

Results

During the exercise periods, there were a meaningful decrease in the body weight, BMI, value of waist region and hip circumference of the women in both intervention groups as well as in the values of HR, DBP, SBP (p < 0,05). In addition, serum homocysteine (Hcy) and high-sensitivity C-reactive protein (Hs-CRP) levels decreased and the VO_2max and left ventricular diastolic end-diastolic dimension increased in both SAG and CEG (p < 0.05). The left ventricular diastolic functions of the SAG improved more than CEG. Left ventricular systolic ejection time and fractional shortening meaningfully improved in both SAG and CEG (p < 0.01).

Conclusion

16 weeks of step-aerobic and core exercise showed significant changes of inflammatory and lipid markers with cardiac dimensions and had favorable effects on both left ventricular systolic function. Left ventricular diastolic function had more improved in SAG than the CEG.

Metabolic Flexibility in Health and Disease

Metabolic flexibility is the ability to respond or adapt to conditional changes in metabolic demand. This broad concept has been propagated to explain insulin resistance and mechanisms governing fuel selection between glucose and fatty acids, highlighting the metabolic inflexibility of obesity and type 2 diabetes. In parallel, contemporary exercise physiology research has helped to identify potential mechanisms underlying altered fuel metabolism in obesity and diabetes. Advances in "omics" technologies have further stimulated additional basic and clinical-translational research to further interrogate mechanisms for improved metabolic flexibility in skeletal muscle and adipose tissue with the goal of preventing and treating metabolic disease.

Associations between physical activity and BMI, body fatness, and visceral adiposity in overweight or obese Latino and non-Latino adults

Background/Objectives

Although several studies have reported associations between moderate to vigorous physical activity (MVPA), body fatness, and visceral adipose tissue (VAT), the extent to which associations differ among Latinos and non-Latinos remains unclear. The present study evaluated the associations between body composition and MVPA in Latino and non-Latino adults.

Subjects/Methods

An exploratory, cross-sectional analysis was conducted using baseline data collected from 298 overweight adults enrolled in a 12-month randomized controlled trial that tested the efficacy of text messaging to improve weight loss. MVPA, body fatness and VAT were assessed by waist-worn accelerometry, DXA, and DXA-derived software (GE CoreScan GE, Madison, WI) respectively. Participants with less than 5 days of accelerometry data or missing DXA data were excluded; 236 participants had complete data. Multivariable linear regression assessed associations between body composition and MVPA per day, defined as time in MVPA, bouts of MVPA (time per bout ≥10 min), non-bouts of MVPA (time per bout <10 min), and meeting the 150-minute MVPA guideline. The modifying influence of ethnicity was modeled with a multiplicative interaction term.

Results

The interaction between ethnicity and MVPA in predicting percent body fat was significant (p = 0.01, 95% CI [0.58, 4.43]) such that a given increase in MVPA was associated with a greater decline in total body fat in non-Latinos compared to Latinos (adjusted for age, sex and accelerometer wear time). There was no interaction between ethnicity and MVPA in predicting VAT (g) (p = 0.78, 95% CI [−205.74, 273.17]) and BMI (p = 0.18, 95% CI [−0.49, 2.26]).

Conclusions

An increase in MVPA was associated with a larger decrease in body fat, but neither BMI nor VAT, in non-Latinos compared to Latinos. This suggests that changes in VAT and BMI in response to MVPA may be less influenced by ethnicity than is total body fatness.

Insulin sensitivity, body composition and adipose depots following 12 w combined endurance and strength training in dysglycemic and normoglycemic sedentary men

CONTEXT

Insulin resistance and dysglycemia are associated with physical inactivity and adiposity, and may be improved by exercise.

OBJECTIVE

Investigate the effect of exercise on insulin sensitivity, body composition and adipose depots in sedentary men with (n = 11) or without (n = 11) overweight and dysglycemia.

MATERIAL AND METHODS

Euglycemic-hyperinsulinemic clamp, ankle-to-neck MRI, MRS, muscle and adipose tissue biopsies before and after 12 weeks combined strength and endurance exercise.

RESULTS

Insulin sensitivity, VO₂max, strength, whole-body and muscle fat content, and abdominal adipose depots were improved without obvious differences between normo- and dysglycemic men. Hepatic fat, waist circumference and subcutaneous adipose tissue were reduced in the dysglycemic group. For both groups plasma adiponectin was reduced, whereas IL-6 was unchanged. Visceral fat was preferentially lost compared with other adipose depots.

DISCUSSION AND CONCLUSION

Body composition, fat distribution and insulin sensitivity improved following training in sedentary middle-aged men with and without dysglycemia.

Exercise as medicine - evidence for prescribing exercise as therapy in 26 different chronic diseases

This review provides the reader with the up-to-date evidence-based basis for prescribing exercise as medicine in the treatment of 26 different diseases: psychiatric diseases (depression, anxiety, stress, schizophrenia); neurological diseases (dementia, Parkinson's disease, multiple sclerosis); metabolic diseases (obesity, hyperlipidemia, metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes, type 1 diabetes); cardiovascular diseases (hypertension, coronary heart disease, heart failure, cerebral apoplexy, and claudication intermittent); pulmonary diseases (chronic obstructive pulmonary disease, asthma, cystic fibrosis); musculo-skeletal disorders (osteoarthritis, osteoporosis, back pain, rheumatoid arthritis); and cancer. The effect of exercise therapy on disease pathogenesis and symptoms are given and the possible mechanisms of action are discussed. We have interpreted the scientific literature and for each disease, we provide the reader with our best advice regarding the optimal type and dose for prescription of exercise.

Leisure-time physical activity and intra-abdominal fat in young adulthood: A monozygotic co-twin control study

OBJECTIVE

To investigate differences in abdominal fat compartments between young adult monozygotic twin pairs discordant for leisure-time physical activity.

METHODS

Ten young adult male monozygotic twin pairs (age range 32-36 years) discordant for leisure-time physical activity during the past 3 years were systematically selected from a population-based Finnish twin cohort. Magnetic resonance image at the level of the L2-L3 intervertebral disc was used to predict intra-abdominal and subcutaneous abdominal fat masses. Dietary intake was assessed with a 4-day food diary.

RESULTS

Inactive twins had 31% more intra-abdominal fat than their active co-twins (mean difference 0.52 kg, 95% CI 0.12 to 0.91, P = 0.016), whereas the difference in subcutaneous abdominal fat was only 13% (P = 0.21) and 3% in body mass index (P = 0.28). Intraperitoneal fat mass was 41% higher among inactive twins compared to their active co-twins (mean difference 0.41 kg, 95% CI 0.11 to 0.70, P = 0.012). Dietary intake did not differ between co-twins.

CONCLUSIONS

A lower level of physical activity is related to greater accumulation of intra-abdominal fat among healthy adult males in their mid-30s. The findings highlight the importance of leisure-time physical activity independent of genes and diet in the prevention of intra-abdominal fat accumulation from early adulthood onward.

Weight loss is not mandatory for exercise-induced effects on health indices in females with metabolic syndrome

The aim of this study was to investigate the impact of moderate aerobic training on functional, anthropometric, biochemical, and health-related quality of life (HRQOL) parameters on women with metabolic syndrome (MS). Fifteen untrained women with MS performed moderate aerobic training for 15 weeks, without modifications of dietary behaviours. Functional, anthropometric, biochemical, control diet record and HRQOL parameters were assessed before and after the training. Despite body weight maintenance, the patients presented decreases in waist circumference (P = 0.001), number of MS components (P = 0.014), total cholesterol (P = 0.049), HDL cholesterol (P = 0.004), LDL cholesterol (P = 0.027), myeloperoxidase activity (P = 0.002) and thiobarbituric acid-reactive substances levels (P = 0.006). There were no differences in total energy, carbohydrate, protein and lipid intake pre- and post-training. Furthermore, improvements in the HRQOL subscales of physical functioning (P = 0.03), role-physical (P = 0.039), bodily pain (P = 0.048), general health (P = 0.046) and social functioning scoring (P = 0.011) were reported. Despite the absence of weight loss, aerobic training induced beneficial effects on functional, anthropometric, biochemical and HRQOL parameters in women with MS.

Associations of physical activity and sedentary behavior with regional fat deposition

INTRODUCTION

Increased sedentary behavior predicts greater cardiovascular morbidity and mortality and does so independently of physical activity (PA). This association is only partially explained by body mass index (BMI) and overall body fat, suggesting mechanisms besides general increased adiposity. The purpose of this study was to explore associations of self-reported leisure PA and sitting time with regional fat depositions and abdominal muscle among community-dwelling older adults.

METHODS

Participants were 539 diverse adults (mean age = 65 yr) who completed a study visit in 2001-2002. Areas of pericardial, intrathoracic, subcutaneous, visceral, and intermuscular fat, as well as abdominal muscle, were measured using computed tomography. Leisure PA and sitting hours were entered simultaneously into multivariate regression models to determine associations with muscle and fat areas.

RESULTS

After adjusting for demographics, smoking, diabetes, hypertension, triglycerides, and cholesterol, greater PA was associated with less intrathoracic, visceral, subcutaneous, and intermuscular fat (for all P < 0.05), while greater sedentary time was associated with greater pericardial and intrathoracic fat (for both P < 0.05). After further adjusting for BMI, each hour of weekly PA was associated with 1.85 cm less visceral fat (P < 0.01) but was not associated with other fat depositions. Conversely, each hour of daily sitting was associated with 2.39 cm more pericardial fat (P < 0.05) but was not associated with any other fat depositions. There were no associations with abdominal muscle area. Adjusting for common inflammatory markers had little effect. Associations between fat and PA were stronger for men.

CONCLUSIONS

Sitting and PA have distinct associations with regional fat deposition in older adults. The association between sitting and pericardial fat could partially explain the link between sitting and coronary heart disease.

Meeting physical activity guidelines is associated with reduced risk for cardiovascular disease in black South African women; a 5.5-year follow-up study

Background

Low levels of physical activity (PA) have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D), but few studies have examined whether meeting international PA guidelines is associated with reduced risk in a black South African (SA) population. The aims of this study were to compare body composition and cardio-metabolic risk factors for CVD and T2D between active and inactive groups (part 1, cross-sectional analysis) and, to determine whether PA level predicts changes in body composition and cardio-metabolic risk factors for CVD and T2D at follow-up after 5.5-years (part 2, longitudinal analysis).

Methods

Part 1 included a sample of 240 apparently healthy black SA women (26 ± 7 years) who underwent the following measurements at baseline: PA (Global Physical Activity Questionnaire (GPAQ)), body composition and regional fat distribution (dual-energy x-ray absorptiometry and computerised tomography), blood pressure, fasting glucose, insulin and lipid concentrations. For part 2, a sub-sample of women (n = 57) underwent the same measurements after a 5.5-year period.

Results

At baseline, 61% of women were classified as meeting the guidelines for moderate- to vigorous-intensity physical activity (MVPA) according to GPAQ. Women who were active had significantly lower body weight (p < 0.001), body fat (BMI, fat mass, % body fat, waist circumference, central and appendicular fat mass, all p < 0.001), and measures of insulin resistance (fasting serum insulin and HOMA-IR, both p = 0.01), and higher high-density lipoprotein cholesterol (p = 0.041), compared to the inactive group. At follow-up, all body fat measures increased significantly in both groups and diastolic blood pressure decreased significantly in those who were active at baseline, but did not change in those who were inactive.

Conclusions

Meeting PA guidelines was associated with decreased risk for CVD and T2D in black SA women, but did not prevent the increase in body fat over time. Interventions promoting physical activity to specifically address obesity in this high-risk group are recommended.

Lifestyle modification and endothelial function in obese subjects

The metabolic syndrome is a cluster of metabolic and vascular abnormalities that include central obesity, insulin resistance, hyperinsulinemia, glucose intolerance, hypertension, dyslipidemia, hypercoagulability and an increased risk of coronary and cerebral vascular disease. These metabolic and vascular abnormalities are the main cause of cardiovascular mortality in western societies. Endothelial dysfunction, an early step in the development of atherosclerosis, has been reported in obese nondiabetic individuals and in patients with Type 2 diabetes. It has also been observed in individuals at high risk for Type 2 diabetes, including those with impaired glucose tolerance and the normoglycemic first-degree relatives of Type 2 diabetic patients. Recent evidence points to adipocytes as a complex and active endocrine tissue whose secretory products, including free fatty acids and several cytokines (i.e., leptin, adiponectin, tissue necrosis factor-alpha, interleukin-6, and resistin) play a major role in the regulation of human metabolic and vascular biology. These adipocytokines have been claimed to be the missing link between insulin resistance and cardiovascular disease. Interventions designed to improve endothelial and/or adipose-tissue functions may reduce cardiovascular events in obese individuals with either the metabolic syndrome or Type 2 diabetes. Lifestyle modification in the form of caloric restriction and increased physical activity are the most common modalities used for treating those individuals at risk and is unanimously agreed to be the initial step in managing Type 2 diabetes. Several recent studies have demonstrated favorable impacts of lifestyle modifications in improving endothelial function and insulin sensitivity, in addition to altering serum levels of adipocytokines and possibly reducing cardiovascular events. This review discusses current knowledge of the role of lifestyle modifications in ameliorating cardiovascular risk in obese subjects with either the metabolic syndrome or Type 2 diabetes.

Effect of exercise on abdominal fat loss in men and women with and without type 2 diabetes

OBJECTIVE

To examine the effect of exercise on abdominal adipose tissue in adults with and without type 2 diabetes mellitus (T2DM).

DESIGN

Post hoc analysis of two randomised controlled trials.

SETTING

Outpatient secondary prevention programme in Baltimore, Maryland, USA.

PARTICIPANTS

97 men and women with prehypertension, stage 1 or medically controlled hypertension. 49% of the sample was also diagnosed with T2DM.

INTERVENTION

All participants completed a 26-week (6.5 months) supervised aerobic and resistance exercise programme following American College of Sports Medicine guidelines.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcomes in this post hoc analysis were total abdominal adipose tissue (TAT), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) measured by MRI. Secondary outcomes were to determine whether the magnitude of abdominal fat change differed by diabetes status in men and women and to identify the predictors of change in abdominal fat distribution with exercise.

RESULTS

Overall, participants (mean age 61±6 years; 45% women) significantly improved peak oxygen uptake by 15% (p<0.01) and reduced weight by 2% (p<0.01). No change in SAT was observed after training. The reduction in VAT following exercise was attenuated in participants with T2DM (-3%) compared with participants who were non-T2DM (-18%, p<0.001 for the difference in change). The magnitude of VAT loss was associated with a decrease in body weight (r=0.50, p<0.001). After adjustment for weight change using regression analysis, diabetes status remained an independent predictor of the change in VAT.

CONCLUSIONS

Although participants with and without T2DM attained an exercise training effect as evidenced by increased fitness, VAT was unchanged in T2DM compared to those without T2DM, suggesting that these individuals may be resistant to this important benefit of exercise. The strategies for reducing cardiovascular disease risk in T2DM may be most effective when they include a weight loss component.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov Registry NCT00212303.

Hepatic steatosis, GH deficiency and the effects of GH replacement: a Liverpool magnetic resonance spectroscopy study

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is reported to be more common in patients with GH deficiency (GHD) than in the general population. we aimed to determine: i) liver fat in patients with GHD compared with age and body mass index (BMI)-matched controls; and ii) effect of 6 months of GH replacement (GHR) on liver fat.

PARTICIPANTS AND METHODS

The study included 28 GHD patients and 24 controls. 12 patients were studied before and after 6 months of GHR. Anthropometry, liver enzymes and lipid profiles were measured, and body composition and intrahepatocellular lipid (IHCL) were determined by magnetic resonance imaging and spectroscopy.

RESULTS

Age and BMI (median (inter-quartile range)) of patients and controls were 52.6 (14) vs 52.6 (12) years (P=0.9) and 27.8 (24.7, 34.7) vs 27.9 (25.1, 32.1) kg/m(2) (P=0.9). IGF1 was lower in the patients (11.5 vs 16.0 nmol/l, P=0.002). There was no difference in liver transaminases, lipids or IHCL between patients and controls (2.8 (1.3, 8.6) vs 5.0 (1.5, 12.7), P=0.72), despite significantly higher visceral fat in GHD patients. Thirty-two percent of patients and 50% of controls had NAFLD (defined as IHCL >5.6%), and the relationship between IHCL and BMI was the same in each group. GHR significantly reduced abdominal subcutaneous and visceral fat in all patients; however, GHR did not reduce liver fat.

CONCLUSIONS

NAFLD is equally common in patients with GHD and matched controls. GHR is associated with a hierarchical reduction in fat deposition (fat loss: visceral > subcutaneous > liver). Further studies involving GHD patients with NAFLD are required to conclude the role of GHR in treating NAFLD.

Efeito de dietas hiperlipídicas com extrato de baru e chocolate sobre a área de adipócitos de ratos submetidos ao exercício físico

INTRODUÇÃO: O acúmulo de tecido adiposo provoca uma série de distúrbios metabólicos, os quais poderiam ser atenuados pela modulação dietética e prática de exercícios físicos. OBJETIVO: Avaliar os efeitos de dietas hipercalóricas/hiperlipídicas com extrato de baru e chocolate associadas ao exercício aeróbio sobre a área de adipócitos e triglicérides hepáticos (TGLhep) de ratos. MÉTODOS: Após o desmame, ratos da linhagem Wistar, com exceção dos controles (dieta Nuvilab®; 3,48kcal/g), foram alimentados com dieta à base de chocolate (4,17kcal/g), por dois meses, para indução da obesidade. Feito isso, os animais foram distribuídos em seis grupos: controle sedentários (CS), controle exercitados (CE), baru sedentários (BS), baru exercitados (BE), chocolate sedentários (CHOS), chocolate exercitados (CHOE), de acordo com a introdução da dieta com extrato de baru e treinamento de natação (2% do peso corporal., 8 sem., 5x/semana, 1h/sessão). Após a morte dos animais, o conteúdo de TGLhep foi determinado e os tecidos adiposos retroperitoneal, inguinal e omental foram removidos, pesados e submetidos à avaliação da área de adipócitos. RESULTADOS: As dietas hipercalóricas aumentaram o peso e a área de células do tecido retroperitoneal em relação à dieta controle (p < 0,05). O exercício reduziu a área de células do tecido omental (CHOE: 6.370,91 ± 7.776,13 < CHOS: 7.341,28 ± 5.862,24µm²) e inguinal (CHOE: 5.147,49 ± 5.712,71 < CHOS: 7.083,11 ± 7.682,40µm²) do grupo chocolate e inguinal do controle (CE: 2.212,87 ± 1.920,34 < CS: 3.386,11 ± 3.973,09µm²). O conteúdo de TGLhep dos animais sedentários apresentou-se mais elevado em relação aos animais exercitados e alimentados com as dietas hipercalóricas (BS: 1,36 ± 0,50 > BE: 0,88 ± 0,43mg.100mg-1; CHOS: 1,77 ± 0,64 > CHOE: 0,86 ± 0,41mg.100mg-1). CONCLUSÃO: O treinamento físico em intensidade leve à moderada reduziu significativamente os depósitos adiposos omental (visceral) e inguinal dos animais alimentados com dieta controle e chocolate. Esse mesmo comportamento não foi reproduzido com a dieta à base de extrato de baru. Os animais exercitados apresentaram menor conteúdo de TGLhep, mesmo na persistência das dietas hiperlipídicas/hipercalóricas.

Excess body fat in obese and normal-weight subjects

Excess body adiposity, especially abdominal obesity and ectopic fat accumulation, are key risk factors in the development of a number of chronic diseases. The advent of in vivo imaging methodologies that allow direct assessment of total body fat and its distribution have been pivotal in this process. They have helped to identify a number of sub-phenotypes in the general population whose metabolic risk factors are not commensurate with their BMI. At least two such sub-phenotypes have been identified: subjects with normal BMI, but excess intra-abdominal (visceral) fat (with or without increased ectopic fat) and subjects with elevated BMI (> 25 kg/m(2)) but low visceral and ectopic fat. The former sub-phenotype is associated with adverse metabolic profiles, while the latter is associated with a metabolically normal phenotype, despite a high BMI. Here, examples of these phenotypes are presented and the value of carrying out enhanced phenotypical characterisation of subjects in interventional studies discussed.

Physical activity and exercise in the regulation of human adipose tissue physiology

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.

Effects of physical activity on cardiovascular disease

Much attention has been directed toward lifestyle modifications as effective means of reducing cardiovascular disease risk. In particular, physical activity has been heavily studied because of its well-known effects on metabolic syndrome, insulin sensitivity, cardiovascular disease risk, and all-cause mortality. However, data regarding the effects of exercise on various stages of the atherosclerosis pathway remain conflicting. The investigators review previously published reports for recent observational and interventional trials investigating the effects of physical activity on markers of (or causal factors for) atherosclerotic burden and vascular disease, including serum lipoproteins, systemic inflammation, thrombosis, coronary artery calcium, and carotid intima-media thickness. In conclusion, the data show a correlation between physical activity and triglyceride reduction, apolipoprotein B reduction, high-density lipoprotein increase, change in low-density lipoprotein particle size, increase in tissue plasminogen activator activity, and decrease in coronary artery calcium. Further research is needed to elucidate the effect of physical activity on inflammatory markers and intima-media thickness.

The missing risk: MRI and MRS phenotyping of abdominal adiposity and ectopic fat

Individual compartments of abdominal adiposity and lipid content within the liver and muscle are differentially associated with metabolic risk factors, obesity and insulin resistance. Subjects with greater intra-abdominal adipose tissue (IAAT) and hepatic fat than predicted by clinical indices of obesity may be at increased risk of metabolic diseases despite their "normal" size. There is a need for accurate quantification of these potentially hazardous depots and identification of novel subphenotypes that recognize individuals at potentially increased metabolic risk. We aimed to calculate a reference range for total and regional adipose tissue (AT) as well as ectopic fat in liver and muscle in healthy subjects. We studied the relationship between age, body-mass, BMI, waist circumference (WC), and the distribution of AT, using whole-body magnetic resonance imaging (MRI), in 477 white volunteers (243 male, 234 female). Furthermore, we used proton magnetic resonance spectroscopy (MRS) to determine intrahepatocellular (IHCL) and intramyocellular (IMCL) lipid content. The anthropometric variable which provided the strongest individual correlation for adiposity and ectopic fat stores was WC in men and BMI in women. In addition, we reveal a large variation in IAAT, abdominal subcutaneous AT (ASAT), and IHCL depots not fully predicted by clinically obtained measurements of obesity and the emergence of a previously unidentified subphenotype. Here, we demonstrate gender- and age-specific patterns of regional adiposity in a large UK-based cohort and identify anthropometric variables that best predict individual adiposity and ectopic fat stores. From these data we propose the thin-on-the-outside fat-on-the-inside (TOFI) as a subphenotype for individuals at increased metabolic risk.

Hypertriglyceridemia secondary to obesity and diabetes

Hypertriglyceridemia is a common lipid abnormality in persons with visceral obesity, metabolic syndrome and type 2 diabetes. Hypertriglyceridemia typically occurs in conjunction with low HDL levels and atherogenic small dense LDL particles and is associated with increased cardiovascular risk. Insulin resistance is often an underlying feature and results in increased free fatty acid (FFA) delivery to the liver due to increased peripheral lipolysis. Increased hepatic VLDL production occurs due to increased substrate availability via FFAs, decreased apolipoprotein B100 degradation and increased lipogenesis. Postprandial hypertriglyceridemia also is a common feature of insulin resistance. Small dense LDL that coexist with decreased HDL particles in hypertriglyceridemic states are highly pro-atherogenic due to their enhanced endothelial permeability, proteoglycan binding abilities and susceptibility to oxidation. Hypertriglyceridemia also occurs in undertreated individuals with type 1 diabetes but intensive glucose control normalizes lipid abnormalities. However, development of visceral obesity in these patients unravels a similar metabolic profile as in patients with insulin resistance. Modest hypertriglyceridemia increases cardiovascular risk, while marked hypertriglyceridemia should be considered a risk for pancreatitis. Lifestyle modification is an important therapeutic strategy. Drug therapy is primarily focused on lowering LDL levels with statins, since efforts at triglyceride lowering and HDL raising with fibrates and/or niacin have not yet been shown to be beneficial in improving cardiovascular risk. Fibrates, however, are first-line agents when marked hypertriglyceridemia is present. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.

Pragmatic study of orlistat 60 mg on abdominal obesity

BACKGROUND/OBJECTIVES

It is well established that combining a reduced calorie, low-fat diet with the lipase inhibitor orlistat results in significantly greater weight loss than placebo plus diet. This weight loss is accompanied by changes in adipose tissue (AT) distribution. As 60 mg orlistat is now available as an over-the-counter medication, the primary objective of this study was to determine whether 60 mg orlistat is effective as a weight loss option in a free-living community population with minimal professional input.

METHODS

AT and ectopic lipid content were measured using magnetic resonance imaging and (1)H MR spectroscopy, respectively, in 27 subjects following 3 months treatment with orlistat 60 mg and a reduced calorie, low-fat diet.

RESULTS

Significant reductions in intra-abdominal AT (-10.6%, P=0.023), subcutaneous (-11.7% P<0.0001) and pericardial fat (-9.8%, P=0.034) volumes and intrahepatocellular lipids (-43.3%, P=0.0003) were observed. These changes in body fat content and distribution were accompanied by improvements in plasma lipids and decreases in blood pressure and heart rate.

CONCLUSION

These findings suggest that over-the-counter 60 mg orlistat, in combination with the type of advice a subject could expect to be given when obtaining 60 mg orlistat in a community setting, does indeed result in potentially clinically beneficial changes in body composition and risk factors for metabolic diseases.

Targeting thermogenesis and related pathways in anti-obesity drug discovery

The health consequences of the obesity epidemic are a huge burden on patients and society. Yet it remains an unmet therapeutic need. Lifestyle or behaviour modification, although desirable, seems to benefit only a few and bariatric surgery is not an option for all and not without risks. Nevertheless, bariatric surgery is currently the gold standard in terms of weight loss therapy and any weight loss agent will be in combination with management of lifestyle modification. Sadly, there is a poor history for the pharmacological treatment of obesity and repeated safety concerns have attracted intense regulatory scrutiny. Indeed, recent market withdrawals leave us with just one agent approved for the long term treatment of obesity and that is only mildly efficacious in terms of weight loss, although it is beneficial in terms of metabolic health. There are two broad pharmacological approaches that can be applied in obesity drug discovery: reduce intake (or absorption) or increase expenditure (thermogenesis) of calories. In this review we will look at the latter approach. We will cover regulatory requirements and the rationale for this approach. We believe that post-obese subjects display abnormal metabolic responses to weight loss that almost inevitably leads to weight regain. We will then explore a number of approaches that potentially increase thermogenesis in humans. The challenge we have is in accumulating enough human data to validate this approach using drugs.

Thermogenesis and related metabolic targets in anti-diabetic therapy

Exercise, together with a low-energy diet, is the first-line treatment for type 2 diabetes type 2 diabetes . Exercise improves insulin sensitivity insulin sensitivity by increasing the number or function of muscle mitochondria mitochondria and the capacity for aerobic metabolism, all of which are low in many insulin-resistant subjects. Cannabinoid 1-receptor antagonists and β-adrenoceptor agonists improve insulin sensitivity in humans and promote fat oxidation in rodents independently of reduced food intake. Current drugs for the treatment of diabetes are not, however, noted for their ability to increase fat oxidation, although the thiazolidinediones increase the capacity for fat oxidation in skeletal muscle, whilst paradoxically increasing weight gain.There are a number of targets for anti-diabetic drugs that may improve insulin sensitivity insulin sensitivity by increasing the capacity for fat oxidation. Their mechanisms of action are linked, notably through AMP-activated protein kinase, adiponectin, and the sympathetic nervous system. If ligands for these targets have obvious acute thermogenic activity, it is often because they increase sympathetic activity. This promotes fuel mobilisation, as well as fuel oxidation. When thermogenesis thermogenesis is not obvious, researchers often argue that it has occurred by using the inappropriate device of treating animals for days or weeks until there is weight (mainly fat) loss and then expressing energy expenditure energy expenditure relative to body weight. In reality, thermogenesis may have occurred, but it is too small to detect, and this device distracts us from really appreciating why insulin sensitivity has improved. This is that by increasing fatty acid oxidation fatty acid oxidation more than fatty acid supply, drugs lower the concentrations of fatty acid metabolites that cause insulin resistance. Insulin sensitivity improves long before any anti-obesity effect can be detected.

Inflammatory modulation of exercise salience: using hormesis to return to a healthy lifestyle

Most of the human population in the western world has access to unlimited calories and leads an increasingly sedentary lifestyle. The propensity to undertake voluntary exercise or indulge in spontaneous physical exercise, which might be termed "exercise salience", is drawing increased scientific attention. Despite its genetic aspects, this complex behaviour is clearly modulated by the environment and influenced by physiological states. Inflammation is often overlooked as one of these conditions even though it is known to induce a state of reduced mobility. Chronic subclinical inflammation is associated with the metabolic syndrome; a largely lifestyle-induced disease which can lead to decreased exercise salience. The result is a vicious cycle that increases oxidative stress and reduces metabolic flexibility and perpetuates the disease state. In contrast, hormetic stimuli can induce an anti-inflammatory phenotype, thereby enhancing exercise salience, leading to greater biological fitness and improved functional longevity. One general consequence of hormesis is upregulation of mitochondrial function and resistance to oxidative stress. Examples of hormetic factors include calorie restriction, extreme environmental temperatures, physical activity and polyphenols. The hormetic modulation of inflammation, and thus, exercise salience, may help to explain the highly heterogeneous expression of voluntary exercise behaviour and therefore body composition phenotypes of humans living in similar obesogenic environments.

Epicardial fat gene expression after aerobic exercise training in pigs with coronary atherosclerosis: relationship to visceral and subcutaneous fat

Epicardial adipose tissue (EAT) is contiguous with coronary arteries and myocardium and potentially may play a role in coronary atherosclerosis (CAD). Exercise is known to improve cardiovascular disease risk factors. The purpose of this study was to investigate the effect of aerobic exercise training on the expression of 18 genes, measured by RT-PCR and selected for their role in chronic inflammation, oxidative stress, and adipocyte metabolism, in peri-coronary epicardial (cEAT), peri-myocardial epicardial (mEAT), visceral abdominal (VAT), and subcutaneous (SAT) adipose tissues from a castrate male pig model of familial hypercholesterolemia with CAD. We tested the hypothesis that aerobic exercise training for 16 wk would reduce the inflammatory profile of mRNAs in both components of EAT and VAT but would have little effect on SAT. Exercise increased mEAT and total heart weights. EAT and heart weights were directly correlated. Compared with sedentary pigs matched for body weight to exercised animals, aerobic exercise training reduced the inflammatory response in mEAT but not cEAT, had no effect on inflammatory genes but preferentially decreased expression of adiponectin and other adipocyte-specific genes in VAT, and had no effect in SAT except that IL-6 mRNA went down and VEGFa mRNA went up. We conclude that 1) EAT is not homogeneous in its inflammatory response to aerobic exercise training, 2) cEAT around CAD remains proinflammatory after chronic exercise, 3) cEAT and VAT share similar inflammatory expression profiles but different metabolic mRNA responses to exercise, and 4) gene expression in SAT cannot be extrapolated to VAT and heart adipose tissues in exercise intervention studies.

Efficacy of increasing physical activity to reduce children's visceral fat: a pilot randomized controlled trial

OBJECTIVE

To examine whether differentially targeting physical activity within the context of pilot family-based pediatric weight control treatment results in differential change in abdominal fat, particularly visceral fat.

METHOD

Twenty-nine overweight children (>85(th) body mass index [BMI] percentile) and at least one participating parent were randomly assigned to one of two family-based behavioral weight management conditions that either targeted 1) primarily dietary change (STANDARD; n = 15) or 2) dietary plus physical activity change (ADDED; n = 14). Differences at post-treatment in overall child weight status (e.g., BMI), whole-body composition (measured by dual x-ray absorptiometry), and abdominal fat (measured by waist circumference and magnetic resonance imaging) were assessed using intent-to-treat analyses, as were post-treatment parent BMI and waist circumference. Child and parent physical activity and dietary behavior changes were also evaluated. Results. At post-treatment, overall child weight status, whole-body composition, and child dietary measures did not differ by condition. Children in the ADDED condition tended to have higher physical activity and lower visceral abdominal fat at post-treatment relative to children in the STANDARD condition.

CONCLUSIONS

Increasing physical activity may be important to optimize reductions in abdominal fat, especially visceral fat, among overweight children provided with family-based behavioral weight management treatment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00359957.

Exercise, body composition, and functional ability: a randomized controlled trial

CONTEXT

In women, age and the menopausal transition contribute to an increase of body fat and a reduction of lean body mass associated with functional decline, affecting independent living.

BACKGROUND

Sarcopenia and adiposity in the elderly has been associated with increased mortality and functional decline affecting independent living.

PURPOSE

This study was conducted to determine the effect of a multipurpose exercise program on the body composition and functional ability of elderly women living in a community.

DESIGN

An 18-month single-blinded RCT comparing participants in an exercise program with an active control group was conducted from May 2005 through December 2007. Analyses were conducted from January 2008 to July 2008.

SETTING/PARTICIPANTS

Two hundred forty-six women (aged 69.1+/-4.0 years) living independently in the area of Erlangen-Nürnberg (Germany) participated in the study.

INTERVENTION

Subjects (n=123) performed a multipurpose exercise program with special emphasis on exercise intensity but with low-level requirements for training facilities and materials. The 123 women in the control group focused primarily on well-being.

MAIN OUTCOME MEASURES

Body composition was assessed by dual-energy x-ray absorptiometry. Further, strength was evaluated using isometric techniques for the back and legs. Aerobic fitness was determined from a progressive-intensity treadmill test.

RESULTS

After 18 months, significant effects in favor of the exercise program for body composition were increases in appendicular skeletal muscle mass and lean body mass along with reductions in abdominal fat and total body fat. Significant performance effects also favored the exercise program and included enhanced isometric maximum trunk-extensor and leg press strength, leg press power, timed up-and-go test, and aerobic fitness.

CONCLUSIONS

A high-intensity multipurpose exercise program produced significant improvements in body composition and functional ability in a cohort of elderly women living in a community.

Exercise and the metabolic syndrome with weight regain

Weight loss improves metabolic syndrome (MetS) factors, but risk may return with weight regain. This study was designed to determine if exercise training can maintain improvements in MetS risk factors during weight regain. In a randomized control trial,102 overweight or obese (body mass index 25.0-39.9 kg/m(2)) men and women (age 21-52 yr), with characteristics of the MetS, lost 10% of body weight with supervised walking/jogging at 60% of maximal oxygen consumption (Vo(2 max)) (-400 kcal/session), 5 days/wk, and caloric restriction (-600 kcal/day) over a 4- to 6-mo period. After weight loss, 77 remaining subjects underwent programmed weight regain (+50% of lost weight) for 4-6 mo with random assignment to two groups: no exercise (NoEX) or continued supervised exercise (EX). Blood pressure, regional fat, glucose homeostasis, lipids, and inflammatory markers were assessed at baseline, post-weight loss, and post-weight regain. Groups were compared by two-way repeated-measures ANOVA on the 67 subjects. After weight loss (9.7 +/- 0.2% of body weight), significant (P < 0.05) improvements were observed in almost all parameters assessed. Following weight regain (54.4 +/- 1.6% of lost weight), the NoEX group exhibited deterioration in most metabolic markers, while the EX group maintained improvements in Vo(2 max), blood pressures, glucose homeostasis, high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), oxidized LDL, and other markers of inflammation, but did not maintain improvements in triglyceride and cholesterol concentrations or abdominal fat. Results of this design of controlled human weight regain suggest that aerobic exercise can counter the detrimental effects of partial weight regain on many markers of disease risk.

Predicting fibrosis worsening in obese patients with NASH through parenchymal fibronectin, HOMA-IR, and hypertension

OBJECTIVES

Few published studies have examined the results obtained from repeat liver biopsies in obese patients with nonalcoholic fatty liver disease (NAFLD). The progressive form of this disease may be largely limited to a subgroup of NAFLD patients with nonalcoholic steatohepatitis (NASH). The presence of intralobular fibronectin (Fn) and other variables was investigated in relation to subsequent fibrosis progression.

METHODS

In this prospective study, 271 obese patients admitted to the hospital with NAFLD and abnormal liver enzymes were scheduled to undergo a repeat liver biopsy at least 5 years after the initial biopsy. After excluding cirrhotic patients, basal biopsy specimens obtained from patients who underwent a second liver biopsy were stained with antibodies against Fn. The progression of fibrosis in the follow-up sample was correlated with the amount of Fn and other clinicopathological variables.

RESULTS

We obtained a second liver biopsy from 149 patients after a median time of 6.4 years. Of these, 132 showed suitable Fn staining for semi-quantitative assessments. In all, 44 out of 83 patients (53%) with basal NASH showed fibrosis progression by at least one stage in the second liver biopsy. The amount of Fn (odds ratio=14.1; P<0.001), a diagnosis of hypertension (odds ratio=4.8; P=0.028), and homeostasis model assessment parameter of insulin resistance (HOMA-IR) scores (>8, odds ratio=1.9; P=0.004) were independent predictive factors of worsening fibrosis.

CONCLUSIONS

A semi-quantitative assessment of the amount of parenchymal Fn present at an early stage in obese patients with NASH is valuable for predicting the progression of fibrosis. Similarly, lobular Fn deposition may be a sensitive and early indicator of active fibrogenetic processes in the liver. Hypertension and higher HOMA-IR scores are other clinical independent risk factors that predict the progression of fibrosis.

The utility of physical activity in the management of global cardiometabolic risk

Major health organizations promote the adoption of a healthy lifestyle, composed of sufficient daily physical activity and a balanced diet for the prevention and management of type 2 diabetes (T2D) and cardiovascular disease risk. In particular, it is recommended that adults accumulate 30 min of moderate-intensity aerobic physical activity on most days of the week. Despite these recommendations, a physically active lifestyle is seldom adopted, and the majority of the North American population remains sedentary. Although the optimal strategy for promoting physical activity in today's environment remains elusive, the evidence for the utility of physical activity in the management of risk factors for T2D and cardiovascular disease is overwhelming. This review examines the influence of aerobic-type physical activity on components of global cardiometabolic risk, that is, the traditional and emerging risk factors for cardiovascular disease and T2D, including visceral obesity, insulin resistance, hypertension, atherogenic dyslipidemia, thrombosis, inflammation, and cardiorespiratory fitness. Where possible, specific consideration is given to the independent effects of an acute bout of physical activity vs. chronic physical activity with weight loss vs. chronic physical activity without weight loss.

Response to Fasting in an Unnaturally Obese Carnivore, the Captive European Polecat Mustela putorius

The European polecat ( Mustela putorius) is a naturally lean carnivore prone to excessive weight gain in captivity. This study assessed its suitability to investigate the natural history of the obese phenotype displayed in overweight humans, domestic animals, and seasonally obese wild mammals. Ten farm-bred polecats were subjected to a 5-day fast with 10 controls. Obesity (40% body fat) was associated with an unfavorable plasma lipid profile and high glucose and insulin concentrations. The polecats were in phase II of fasting with normoglycemia, low liver carbohydrate stores, and decreased plasma concentrations of urea and most amino acids. Although the plasma nonesterified fatty acid (NEFA) levels were elevated, the adipose tissue lipase activities suggested a blunted lipolytic response. Lipid mobilization was more efficient from intraabdominal fat. The animals developed hepatic lipidosis with elevated NEFA influx into the liver and losses of n-3 polyunsaturated fatty acids and arginine as hypothetical etiological factors. The plasma leptin, insulin, and triiodothyronine levels decreased but were not accompanied by reduced sex steroid or increased stress hormone concentrations. The blunted lipolytic response often encountered in obesity suggests that the organism is trying to defend the obese phenotype. Liver lipidosis and decreased insulin and triiodothyronine levels seem to be among the most consistent responses to fasting manifested in diverse mammalian orders and different levels of body fatness. The polecat could be recommended as an easily accessible carnivorean model to study the natural history of the obese phenotype and its comorbidities.

Comparable reduction of the visceral adipose tissue depot after a diet-induced weight loss with or without aerobic exercise in obese subjects: a 12-week randomized intervention study

OBJECTIVE

Weight loss with preferential effect on the visceral adipose tissue (VAT) depot could have important clinical benefits. In this study, we investigated the independent and combined effect of regular exercise and diet induced weight loss on body fat distribution. DESIGN; Randomized control design of i) exercise-only (EXO; 12 weeks of exercise without diet-restriction), ii) hypocaloric-diet (DIO; 8 weeks of very low energy diet (VLED 600 kcal/day) followed by 4-weeks weight maintenance diet) and iii) hypocaloric-diet and exercise (DEX; 8 weeks VLED 800 kcal/day+a 4-week weight maintenance diet combined with exercise throughout the 12 weeks).

SUBJECTS

Seventy-nine obese males and females were included.

MEASUREMENTS

Body fat distribution was quantified by magnetic resonance imaging (MRI)-technology.

RESULTS

In the EXO group, the weight loss (3.5 kg) and the relative reduction in VAT (18%) was significantly lower compared with the weight losses in the DIO and DEX groups (12.3 kg; P<0.01) and to the reduction in VAT (30-37%; P<0.01). In all the three groups, the relative reduction of VAT was higher as compared with the reduction in fat mass (FM; combining all fat depots determined by MRI; P<0.01 for all comparisons). The changes in VAT were associated with changes in FM and related to the initial VAT/FM ratio (r(2)=0.72; P<0.01).

CONCLUSION

Exercise has no additional effects in reduction of the VAT depot, compared with the major effects of hypocaloric diet alone. In addition, the effects of exercise per se on VAT are relatively limited. The effects on the VAT depot are closely associated with changes in total FM.

Is weight loss the optimal target for obesity-related cardiovascular disease risk reduction?

In the present review, it is argued that while weight loss is associated with substantial reduction in obesity-related cardiovascular disease risk and remains a desired outcome of relevant treatment strategies, increasing physical activity is associated with marked reduction in waist circumference, visceral fat and cardiometabolic risk factors, concurrent with an increase in cardiorespiratory fitness despite minimal or no change in body weight. Failure to recognize the benefits of exercise independent of weight loss masks opportunities to counsel and educate patients whose sole criteria for gauging obesity reduction success is the bathroom scale.

The discovery of drugs for obesity, the metabolic effects of leptin and variable receptor pharmacology: perspectives from beta3-adrenoceptor agonists

Although beta3-adrenoceptor (beta3AR) agonists have not become drugs for the treatment of obesity or diabetes, they offer perspectives on obesity drug discovery, the physiology of energy expenditure and receptor pharmacology. beta3AR agonists, some of which also stimulate other betaARs in humans, selectively stimulate fat oxidation in rodents and humans. This appears to be why they improve insulin sensitivity and reduce body fat whilst preserving lean body mass. Regulatory authorities ask that novel anti-obesity drugs improve insulin sensitivity and reduce mainly body fat. Drugs that act on different targets to stimulate fat oxidation may also offer these benefits. Stimulation of energy expenditure may be easy to detect only when the sympathetic nervous system is activated. Leptin resembles beta3AR agonists in that it increases fat oxidation, energy expenditure and insulin sensitivity. This is partly because it raises sympathetic activity, but it may also promote fat oxidation by directly stimulating muscle leptin receptors. The beta1AR and beta2AR can, like the beta3AR, display atypical pharmacologies. Moreover, the beta3AR can display variable pharmacologies of its own, depending on the radioligand used in binding studies or the functional response measured. Studies on the beta3AR demonstrate both the difficulties of predicting the in vivo effects of agonist drugs from in vitro data and that there may be opportunities for identifying drugs that act at a single receptor but have different profiles in vivo.

Themed Review: Lifestyle Treatment of the Metabolic Syndrome

The metabolic syndrome is a clustering of metabolic risk factors including abdominal obesity, dysfunctional glucose metabolism, dyslipidemia, and elevated blood pressure. Approximately 1 in 4 Americans currently has the metabolic syndrome and are thus at an elevated risk of cardiovascular disease, type 2 diabetes, and mortality. Leading health authorities recommend lifestyle modification consisting of exercise and caloric restriction for treatment and prevention of the metabolic syndrome. The purpose of this report is to review the evidence that considers lifestyle modification as a treatment strategy for the metabolic syndrome. The influence of lifestyle modification on abdominal obesity, dysfunctional glucose metabolism, dyslipidemia, and elevated blood pressure is considered. Findings suggest that interventions consisting of exercise and/or caloric restriction are associated with improvement in all components of the metabolic syndrome, although the magnitude of this effect varies according to the specific component studied and additional factors such as baseline values. The evidence presented supports the promotion of lifestyle modification as an efficacious strategy for the treatment of the metabolic syndrome.

Factors associated with percent change in visceral versus subcutaneous abdominal fat during weight loss: findings from a systematic review

BACKGROUND

Visceral adipose tissue (VAT) is associated with greater obesity-related metabolic disturbance. Many studies have reported preferential loss of VAT with weight loss.

OBJECTIVE

This systematic review looks for factors associated with preferential loss of VAT relative to subcutaneous abdominal fat (SAT) during weight loss.

DESIGN

Medline and Embase were searched for imaging-based measurements of VAT and subcutaneous abdominal adipose tissue (SAT) before and after weight loss interventions. We examine for factors that influences the percentage change in VAT versus SAT (%deltaV/%deltaS) with weight loss. Linear regression analyses were performed on the complete data set and on subgroups of studies. Factors examined included percentage weight loss, degree of caloric restriction, exercise, initial body mass index (BMI), gender, time of follow-up and baseline VAT/SAT.

RESULTS

There were 61 studies with a total of 98 cohort time points extracted. Percentage weight loss was the only variable that influenced %deltaV/%deltaS (r=-0.29, P=0.005). Modest weight loss generated preferential loss of VAT, but with greater weight loss this effect was attenuated. The method of weight loss was not an influence with one exception. Very-low-calorie diets (VLCDs) provided exceptional short-term (<4 weeks) preferential VAT loss. But this effect was lost by 12-14 weeks.

CONCLUSIONS

Visceral adipose tissue is lost preferentially with modest weight loss, but the effect is attenuated with greater weight loss. Acute caloric restriction, using VLCD, produces early preferential loss of VAT. These observations may help to explain the metabolic benefits of modest weight loss.

Exercise capacity and cardiovascular/metabolic characteristics of overweight and obese individuals with type 2 diabetes: the Look AHEAD clinical trial

OBJECTIVE

We examined associations of cardiovascular, metabolic, and body composition measures with exercise capacity using baseline data from 5,145 overweight and/or obese (BMI > or = 25.0 kg/m2) men and women with type 2 diabetes who were randomized participants for the Look AHEAD (Action for Health in Diabetes) clinical trial.

RESEARCH DESIGN AND METHODS

Peak exercise capacity expressed as METs and estimated from treadmill speed and grade was measured during a graded exercise test designed to elicit a maximal effort. Other measures included waist circumference, BMI, type 2 diabetes duration, types of medication used, A1C, history of cardiovascular disease, metabolic syndrome, beta-blocker use, and race/ethnicity.

RESULTS

Peak exercise capacity was higher for men (8.0 +/- 2.1 METs) than for women (6.7 +/- 1.7 METs) (P < 0.001). Exercise capacity also decreased across each decade of age (P < 0.001) and with increasing BMI and waist circumference levels in both sexes. Older age, increased waist circumference and BMI, a longer duration of diabetes, increased A1C, a history of cardiovascular disease, having metabolic syndrome, beta-blocker use, and being African American compared with being Caucasian were associated with a lower peak exercise capacity for both sexes. Hypertension and use of diabetes medications were associated with lower peak exercise capacity in women.

CONCLUSIONS

Individuals with diabetes who are overweight or obese have impaired exercise capacity, which is primarily related to age, female sex, and race, as well as poor metabolic control, BMI, and central obesity.

Changes in body composition with weight loss: obese subjects randomized to surgical and medical programs

OBJECTIVE

To assess changes in body composition with weight loss in obese subjects randomized to a laparoscopic adjustable gastric band surgical program or a medical program using a very-low-energy diet and orlistat.

RESEARCH METHODS AND PROCEDURES

Using body composition measurements by DXA, neutron activation for total body nitrogen, and whole body gamma counting for total body potassium, we studied changes in fat mass, fat distribution, fat-free mass, total bone mineral content, total body protein, and body cell mass at 6 (n = 61 paired) and 24 months (n = 53 paired) after randomization.

RESULTS

At 24 months, the surgical group had lost significantly more weight (surgical, 20.3 +/- 6.5 kg; medical, 5.9 +/- 8.0 kg). There was favorable fat-free mass to fat mass loss ratios for both groups (surgical, 1:5.5; medical, 1:5.9). Changes in total body nitrogen or potassium were favorable in each group. A small reduction in mean bone mineral content occurred throughout the study but was not associated with extent of weight loss or treatment group. At 6 months, weight loss for both groups was similar (surgical, 14.1 +/- 4.5 kg; medical, 13.3 +/- 7.3 kg). The medical program subjects lost less fat-free mass and skeletal muscle and had increased total body protein. The proportion of body fat to limb fat remained remarkably constant throughout the study.

DISCUSSION

Weight loss programs used in this study induced fat loss without significant deleterious effects on the components of fat-free mass.

Approximation of total visceral adipose tissue with a single magnetic resonance image

BACKGROUND

A single axial image measured between the 4th and 5th lumbar vertebrae (L4-L5) is most frequently chosen to approximate total abdominal visceral adipose tissue (VAT) volume, but growing evidence suggests that this measurement site is not ideal.

OBJECTIVE

The objective was to determine the single magnetic resonance (MR) image that best approximates the total VAT volume in a biracial sample of healthy subjects.

DESIGN

We used contiguous abdominal MR images to measure VAT area and summed them to determine total VAT volume. The sample included 820 healthy men and women (n = 692 whites, 128 blacks) aged 18-88 y.

RESULTS

A range of MR images had equally high correlations with total VAT in each race and sex group. The image 6 cm above L4-L5 (L4-L5 + 6) was within the best equivalent range for all race and sex groups. The L4-L5 + 6 image crossed the L3 vertebra in 85% of subjects and crossed the L2-L3 intervertebral space or the L2 vertebra for 15% of subjects. Linear regression models indicated that the L4-L5 + 6 image explained 97% of the variance in total abdominal VAT volume, and additional covariates did not increase the R(2) value significantly. The L4-L5 image explained 83% of the variance in VAT volume, and the covariates accounted for an additional 7% of the variance. Rank-order values for VAT can change if total VAT volume is approximated by a single image area. Whereas 25% of subjects changed rank by >or=10% with the L4-L5 image, only 3% changed rank to that degree with the L4-L5 + 6 image.

CONCLUSIONS

A single MR image located approximately at the L3 vertebra can accurately estimate total VAT volume in blacks and whites of both sexes.

Heart positive: design of a randomized controlled clinical trial of intensive lifestyle intervention, niacin and fenofibrate for HIV lipodystrophy/dyslipidemia

Dyslipidemia and insulin resistance occur in a large proportion of HIV-infected patients treated with highly active antiretroviral therapy (HAART); anthropomorphic changes, such as lipoatrophy and central obesity, occur in a subset of patients. This cluster of clinical features, which is termed HIV lipodystrophy, places patients at increased risk for cardiovascular disease. Currently, there is no consensus on the appropriate therapy for the management of HIV lipodystrophy for which the underlying defects are enhanced lipolysis, impaired fat oxidation, increased hepatic VLDL-triglyceride synthesis and secretion, and impaired disposal of intestinally-derived lipoprotein-triglycerides. We describe the design of a randomized, placebo-controlled trial to compare the effects of usual care to diet, exercise and lipid-lowering drugs on lipid profiles of patients with HIV lipodystrophy. The trial will randomize 200 patients into five groups. Outcomes of usual care, diet and exercise alone or in combination with niacin, fenofibrate or both medications will be compared after six months. Unique aspects of the design include an interactive Internet Diet Management system to increase ATP-III recommended dietary compliance for metabolic syndrome, and a supervised program of aerobic and resistance exercises. The study is powered to detect a 20% decrease in triglycerides with the lifestyle intervention and an additional 20% improvement with the addition of niacin and/or fenofibrate. Secondary outcomes include assessment of lipid profile changes, LDL and HDL particle size, plasma cholesterol ester transport protein activity, visceral and subcutaneous fat distribution, glucose tolerance, insulin resistance, and leptin and adiponectin levels.

The influence of physical activity on abdominal fat: a systematic review of the literature

The relationship between excess abdominal adipose tissue, metabolic and cardiovascular health risk has stimulated interest in the efficacy of physical activity in specifically perturbing this adipose depot. The evolution of imaging techniques has enabled more direct measurement of changes in abdominal and visceral fat. The purpose of this summary was to systematically review the relationship between physical activity and abdominal fat.

METHODS

Database searches were performed on MEDLINE, CINAHL, SPORT DISCUS and PUBMED, from 1985 to 2005 with keywords "exercise", "abdominal fat" and "visceral fat".

RESULTS

Nineteen randomized controlled trials (RCTs) and eight non-randomized controlled trials were selected. In RCTs using imaging techniques to measure change in abdominal fat in overweight or obese subjects, seven out of 10 studies (including three trials with type 2 diabetics) reported significant reductions compared with controls. Reductions in visceral and total abdominal fat may occur in the absence of changes in body mass and waist circumference. Waist-to-hip ratio is not a sensitive measure of change in regional adiposity in exercise studies. No studies fulfil the Consolidated Standards of Reporting Trials (CONSORT) statement's criteria for the highest quality of randomized trial; however, many studies were in progress or published before the opportunity to comply with these recommendations. Therefore, limited evidence from a number of studies suggests a beneficial influence of physical activity on reduction in abdominal and visceral fat in overweight and obese subjects when imaging techniques are used to quantify changes in abdominal adiposity. More rigorous studies are needed to confirm these observations.

Organization of circadian functions: interaction with the body

The hypothalamus integrates information from the brain and the body; this activity is essential for survival of the individual (adaptation to the environment) and the species (reproduction). As a result, countless functions are regulated by neuroendocrine and autonomic hypothalamic processes in concert with the appropriate behaviour that is mediated by neuronal influences on other brain areas. In the current chapter attention will be focussed on fundamental hypothalamic systems that control metabolism, circulation and the immune system. Herein a system is defined as a physiological and anatomical functional unit, responsible for the organisation of one of these functions. Interestingly probably because these systems are essential for survival, their function is highly dependent on each other's performance and often shares same hypothalamic structures. The functioning of these systems is strongly influenced by (environmental) factors such as the time of the day, stress and sensory autonomic feedback and by circulating hormones. In order to get insight in the mechanisms of hypothalamic integration we have focussed on the influence of the biological clock; the suprachiasmatic nucleus (SCN) on processes that are organized by and in the hypothalamus. The SCN imposes its rhythm onto the body via three different routes of communication: 1.Via the secretion of hormones; 2. via the parasympathetic and 3.via the sympathetic autonomous nervous system. The SCN uses separate connections via either the sympathetic or via the parasympathetic system not only to prepare the body for the coming change in activity cycle but also to prepare the body and its organs for the hormones that are associated with such change. Up till now relatively little attention has been given to the question how peripheral information might be transmitted back to the SCN. Apart from light and melatonin little is known about other systems from the periphery that may provide information to the SCN. In this chapter attention will be paid to e.g. the role of the circumventricular organs in passing info to the SCN. Herein especially the role of the arcuate nucleus (ARC) will be highlighted. The ARC is crucial in the maintenance of energy homeostasis as an integrator of long- and short-term hunger and satiety signals. Receptors for metabolic hormones like insulin, leptin and ghrelin allow the ARC to sense information from the periphery and signal it to the central nervous system. Neuroanatomical tracing studies using injections of a retrograde and anterograde tracer into the ARC and SCN showed a reciprocal connection between the ARC and the SCN which is used to transmit feeding related signals to the SCN. The implications of multiple inputs and outputs of the SCN to the body will be discussed in relation with metabolic functions.