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Reducing Liver Fat by Low Carbohydrate Caloric Restriction Targets Hepatic Glucose Production in Non-Diabetic Obese Adults with Non-Alcoholic Fatty Liver Disease. J Clin Med 2015; 3:1050-63. [PMID: 25411646 PMCID: PMC4234060 DOI: 10.3390/jcm3031050] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) impairs liver functions, the organ responsible for the regulation of endogenous glucose production and thus plays a key role in glycemic homeostasis. Therefore, interventions designed to normalize liver fat content are needed to improve glucose metabolism in patients affected by NAFLD such as obesity. Objective: this investigation is designed to determine the effects of caloric restriction on hepatic and peripheral glucose metabolism in obese humans with NAFLD. Methods: eight non-diabetic obese adults were restricted for daily energy intake (800 kcal) and low carbohydrate (<10%) for 8 weeks. Body compositions, liver fat and hepatic glucose production (HGP) and peripheral glucose disposal before and after the intervention were determined. Results: the caloric restriction reduced liver fat content by 2/3 (p = 0.004). Abdominal subcutaneous and visceral fat, body weight, BMI, waist circumference and fasting plasma triglyceride and free fatty acid concentrations all significantly decreased (p < 0.05). The suppression of post-load HGP was improved by 22% (p = 0.002) whereas glucose disposal was not affected (p = 0.3). Fasting glucose remained unchanged and the changes in the 2-hour plasma glucose and insulin concentration were modest and statistically insignificant (p > 0.05). Liver fat is the only independent variable highly correlated to HGP after the removal of confounders. Conclusion: NAFLD impairs HGP but not peripheral glucose disposal; low carbohydrate caloric restriction effectively lowers liver fat which appears to directly correct the HGP impairment.
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Abstract
Numerous epidemiologic studies have implicated abdominal obesity as a major risk factor for insulin resistance, type 2 diabetes mellitus, cardiovascular disease, stroke, metabolic syndrome and its further expression, i.e., nonalcoholic fatty liver disease and death. Using novel models of visceral obesity, several studies have demonstrated that the relationship between visceral fat and longevity is causal, while the accrual of subcutaneous fat does not appear to play an important role in the etiology of disease risk. The need of reducing the visceral fat to improve survival, mainly taking into account the strict link between nonalcoholic fatty liver disease and the coronary artery disease is discussed.
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Affiliation(s)
- Carmine Finelli
- Center of Obesity and Eating Disorder, Stella Maris Mediterraneo Foundation Chiaromonte, Potenza, Italy
| | - Giovanni Tarantino
- Department of Clinical and Experimental Medicine, Federico II University Medical School of Naples, Naples, Italy.
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MRI measurement of liver fat content predicts the metabolic syndrome. DIABETES & METABOLISM 2013; 39:314-21. [PMID: 23523139 DOI: 10.1016/j.diabet.2013.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 01/21/2013] [Accepted: 01/30/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND AIMS The prevalence of non-alcoholic fatty liver disease among cardiometabolic patients is not completely known because liver biopsy cannot be routinely performed. However, as magnetic resonance imaging (MRI) allows accurate and safe measurement of the hepatic fat fraction (HFF), the aim of this study was to quantify liver fat content in a dysmetabolic adult population. METHODS A total of 156 adults were included in this cross-sectional study. Liver and visceral fat were assessed by MRI in these subjects, who presented with zero to five metabolic components of the metabolic syndrome (MetS). Arterial stiffness was recorded by ultrasonography, and the maximum Youden index was used to set the optimal HFF cutoff value predictive of the presence of the MetS. RESULTS Overall, 72% of participants displayed three or more MetS components. HFF ranged from 0.3% to 52% (mean 13.4%). Age- and gender-adjusted HFF was positively correlated with BMI (r=0.44), blood pressure (r=0.19), triglyceridaemia (r=0.22) and glycaemia (r=0.31). MRI-measured visceral adipose tissue did not influence the relationship of steatosis with glycaemia, HOMA-IR and carotid stiffness, but there was a dose-response relationship between the number of MetS components and mean HFF. The optimal HFF for predicting the MetS was found to be 5.2% according to the maximum Youden index point. CONCLUSION This study highlighted the impact of liver steatosis on cardiometabolic abnormalities with an optimal cutoff value of 5.2% for defining increased metabolic risk.
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Beneficial effects of an 8-week, very low carbohydrate diet intervention on obese subjects. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:760804. [PMID: 23573151 PMCID: PMC3612489 DOI: 10.1155/2013/760804] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 02/18/2013] [Accepted: 02/18/2013] [Indexed: 12/28/2022]
Abstract
Aim. To investigate the effects of weight loss during an 8-week very low carbohydrate diet (VLCD) on improvement of metabolic parameters, adipose distribution and body composition, and insulin resistance and sensitivity in Chinese obese subjects. Methods. Fifty-three healthy obese volunteers were given an 8-week VLCD. The outcomes were changes in anthropometry, body composition, metabolic profile, abdominal fat distribution, liver fat percent (LFP), and insulin resistance and sensitivity. Results. A total of 46 (86.8%) obese subjects completed the study. The VLCD caused a weight loss of −8.7 ± 0.6 kg (mean ± standard error (SE), P < 0.0001) combined with a significant improvement of metabolic profile. In both male and female, nonesterified fatty acid (NEFA) significantly decreased (−166.2 ± 47.6 μmol/L, P = 0.001) and β-hydroxybutyric acid (BHA) increased (0.15 ± 0.06 mmol/L, P = 0.004) after eight weeks of VLCD intervention. The significant reductions in subcutaneous fat area (SFA), visceral fat area (VFA), and LFP were −66.5 ± 7.9 cm2, −35.3 ± 3.9 cm2, and −16.4 ± 2.4%, respectively (all P values P < 0.0001). HOMA IR and HOMA β significantly decreased while whole body insulin sensitivity index (WBISI) increased (all P values P < 0.001). Conclusion. Eight weeks of VLCD was an effective intervention in obese subjects. These beneficial effects may be associated with enhanced hepatic and whole-body lipolysis and oxidation.
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Hallsworth K, Fattakhova G, Hollingsworth KG, Thoma C, Moore S, Taylor R, Day CP, Trenell MI. Resistance exercise reduces liver fat and its mediators in non-alcoholic fatty liver disease independent of weight loss. Gut 2011; 60:1278-83. [PMID: 21708823 PMCID: PMC3152868 DOI: 10.1136/gut.2011.242073] [Citation(s) in RCA: 322] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Lifestyle interventions focusing on weight loss remain the cornerstone of non-alcoholic fatty liver disease (NAFLD) management. Despite this, the weight losses achieved in research trials are not easily replicated in the clinic and there is an urgent need for therapies independent of weight loss. Aerobic exercise is not well sustained and the effectiveness of the better tolerated resistance exercise upon liver lipid and mediators of liver lipid has not been assessed. METHODS Sedentary adults with clinically defined NAFLD were assigned to 8 weeks of resistance exercise (n=11) or continued normal treatment (n=8). RESULTS 8 weeks of resistance exercise elicited a 13% relative reduction in liver lipid (14.0 ± 9.1 vs. 12.2 ± 9.0; p<0.05). Lipid oxidation (submaximal RQ -0.020 ± 0.010 vs. -0.004 ± 0.003; p<0.05), glucose control (-12% vs. +12% change AUC; p<0.01) and homeostasis model assessment insulin resistance (5.9 ± 5.9 to 4.6 ± 4.6 vs. 4.7 ± 2.1 to 5.1 ± 2.5; p<0.05) were all improved. Resistance exercise had no effect on body weight, visceral adipose tissue volume, or whole body fat mass (p>0.05). CONCLUSION This is the first study to demonstrate that resistance exercise specifically improves NAFLD independent of any change in body weight. These data demonstrate that resistance exercise may provide benefit for the management for non-alcoholic fatty liver, and the long-term impact of this now requires evaluation.
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Affiliation(s)
- Kate Hallsworth
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK,MRC Centre for Brain Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
| | - Gulnar Fattakhova
- NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK
| | - Kieren G Hollingsworth
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK
| | - Christian Thoma
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK,MRC Centre for Brain Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
| | - Sarah Moore
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK,MRC Centre for Brain Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
| | - Roy Taylor
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher P Day
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK
| | - Michael I Trenell
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK,NIHR Biomedical Research Centre for Ageing and Age-related Disease, Newcastle University, Newcastle upon Tyne, UK,MRC Centre for Brain Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
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Nunn AV, Guy GW, Brodie JS, Bell JD. Inflammatory modulation of exercise salience: using hormesis to return to a healthy lifestyle. Nutr Metab (Lond) 2010; 7:87. [PMID: 21143891 PMCID: PMC3009972 DOI: 10.1186/1743-7075-7-87] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/09/2010] [Indexed: 02/07/2023] Open
Abstract
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.
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Affiliation(s)
- Alistair V Nunn
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, Du Cane Road, London W12 OHS, UK.
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