Differential effects of macronutrient content in 2 energy-restricted diets on cardiovascular risk factors and adipose tissue cell size in moderately obese individuals: a randomized controlled trial.

BACKGROUND: The most effective and safe dietary approach for weight loss and its impact on the metabolic functions and morphology of adipose tissue remain unclear. OBJECTIVES: We evaluated whether an energy-restricted high-protein diet with a low glycemic index and soluble fiber (LC-P-LGI) would be more effective than a low-calorie conventional diet (LC-CONV) on weight loss and related metabolic risk factors. We further determined factors that may influence adipocyte size during energy restriction. DESIGN: Thirteen obese participants were randomly assigned in a crossover design to 2 periods of a 4-wk hypocaloric diet as either LC-P-LGI or LC-CONV, separated by 8-wk washout intervals. RESULTS: In comparison with the LC-CONV diet, the main effect of the LC-P-LGI diet was a greater decrease in adipocyte diameter (P = 0.048), plasma plasminogen activator inhibitor protein-1 (P = 0.019), vascular endothelial growth factor (P = 0.032), and interferon-γ inducible protein 10 (P = 0.010). Whereas fasting plasma glucose and high-sensitivity C-reactive protein decreased only after the LC-P-LGI diet, with no differences between diets, fasting plasma insulin and insulin resistance were lower after the LC-CONV diet. The diet results did not differ for body composition and lipid variables. Kinetic modifications in adipocyte diameter were associated with metabolic variables and genes implicated in adipocyte proliferation, apoptosis, and angiogenesis. CONCLUSIONS: In comparison with the LC-CONV diet, the LC-P-LGI diet was associated with improvement in some cardiometabolic risk factors and greater reduction in adipocyte size. Profiles of genes involved in inhibiting adipogenesis and angiogenesis, but increasing apoptosis, were correlated with decreased adipocyte size. This study provides insight into the adipose tissue-remodeling changes that induce regulation of adipocyte size during dietary weight loss. This trial was registered at clinicaltrials.gov as NCT01312740.

Independent and opposite associations of trunk fat and leg fat with liver enzyme levels.

BACKGROUND: In contrast to trunk fat mass (TFM), which is associated with cardiovascular risk markers, leg fat mass (LFM) displays independent protective effects against atherosclerosis. Little is known about the respective influence of central and peripheral adiposity on liver enzyme levels. AIMS: To assess the respective influence of TFM and LFM on alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) levels, and to test whether LFM might protect against an increase of liver enzyme levels. METHODS: Cross-sectional study on 1442 patients (women: 1155; men: 287) referred for overweight/obesity over 3 years. Body composition was analysed by dual-energy X-ray absorptiometry. The relationships among liver enzymes, age, weight, height, body mass index (BMI), biological indices and body composition were studied. RESULTS: The mean BMI was 39.7 +/- 7.9 kg/m(2) in women and 38.2 +/- 6.6 kg/m(2) in men. In women, after adjustement for confounding factors, ALT, AST and GGT were negatively and independently correlated with LFM and positively with TFM. Similar independent associations were observed for ALT and AST in men. The strongest associations were found for ALT in both women and men. CONCLUSIONS: As observed for cardiovascular risk factors, LFM and TFM are inversely and independently correlated with liver enzyme levels in obese patients. LFM may confer independent protective effects against obesity-associated liver damage.

Improved plasma glucose control, whole-body glucose utilization, and lipid profile on a low-glycemic index diet in type 2 diabetic men: a randomized controlled trial.

OBJECTIVE: To determine whether a chronic low-glycemic index (LGI) diet, compared with a high-glycemic index (HGI) diet, has beneficial effects on plasma glucose control, lipid metabolism, total fat mass, and insulin resistance in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Twelve type 2 diabetic men were randomly allocated to two periods of 4 weeks of an LGI or HGI carbohydrate diet separated by a 4-week washout interval, in a crossover design. RESULTS: The LGI diet induced lower postprandial plasma glucose and insulin profiles and areas under the curve than after the HGI diet. At the end of the two dietary periods, the 7-day dietary records demonstrated equal daily total energy and macronutrient intake. Body weight and total fat mass were comparable. Four-week LGI versus HGI diet induced improvement of fasting plasma glucose (P < 0.01, Delta changes during LGI vs. HGI), HbA(1c) (P < 0.01), and whole-body glucose utilization measured by the euglycemic-hyperinsulinemic clamp (P < 0.05). LGI diet induced a decrease in fasting plasma total and LDL cholesterol (Delta changes LGI vs. HGI, P < 0.01), free fatty acids (P < 0.01), apolipoprotein B, and plasminogen activator inhibitor 1 activity. CONCLUSIONS: Only 4 weeks of an LGI diet was able to improve glycemic control, glucose utilization, some lipid profiles, and the capacity for fibrinolysis in type 2 diabetes. Even if changes in glycemic control were modest during the 4-week period, the use of an LGI diet in a longer-term manner might play an important role in the treatment and prevention of diabetes and related disorders.

Dietary fish oil increases lipid mobilization but does not decrease lipid storage-related enzyme activities in adipose tissue of insulin-resistant, sucrose-fed rats.

Fish oil feeding has been shown to limit visceral fat accumulation in insulin-resistant rats. Our goal was to determine whether this finding is due to increased fat mobilization or decreased lipid storage. Adipocytes were isolated from rats fed for 3 wk a diet containing 57.5 g/100 g sucrose and 14 g/100 g lipids as either fish oil (SF) or a mixture of standard oils (SC); there was also a reference group (R). Substituting fish oil for standard oils protected rats from visceral fat hypertrophy, hypertriglyceridemia and hyperglycemia. The stimulation of lipolysis was greater in adipocytes isolated from SF-fed rats than in those from SC-fed rats. Fatty acid synthase (FAS) activity was markedly lower in the liver but not in the adipose tissues of rats fed SF. Lipoprotein lipase (LPL) activity was 2.2-fold higher in the adipose tissues but not in the muscle in rats fed the SF diet than in those fed the SC diet. The decrease in visceral fat in rats fed fish oil could be attributed to decreased plasma triacylglycerol concentration and/or increased lipid mobilization rather than to reduced lipid storage.