OBJECTIVE -Central obesity is associated with insulin resistance through factors that are not fully understood. We studied the effects of three different isocaloric diets on body fat distribution, insulin sensitivity, and peripheral adiponectin gene expression. RESEARCH DESIGN AND METHODS-Eleven volunteers, offspring of obese type 2 diabetic patients with abdominal fat deposition, were studied. These subjects were considered insulin resistant as indicated by Matsuda index values Ͻ4 after an oral glucose tolerance test, and they maintained A1C Ͻ6.5% without therapeutic intervention. All subjects underwent three dietary periods of 28 days each in a crossover design: 1) diet enriched in saturated fat (SAT), 2) diet rich in monounsaturated fat (MUFA) (Mediterranean diet), and 3) diet rich in carbohydrates (CHOs).RESULTS -Weight, body composition, and resting energy expenditure remained unchanged during the three sequential dietary periods. Using dual-energy X-ray absorptiometry we observed that when patients were fed a CHO-enriched diet, their fat mass was redistributed toward the abdominal depot, whereas periphery fat accumulation decreased compared with isocaloric MUFA-rich and high-SAT diets (ANOVA P Ͻ 0.05). Changes in fat deposition were associated with decreased postprandial mRNA adiponectin levels in peripheral adipose tissue and lower insulin sensitivity index values from a frequently sampled insulin-assisted intravenous glucose tolerance test in patients fed a CHO-rich diet compared with a MUFA-rich diet (ANOVA P Ͻ 0.05).CONCLUSIONS -An isocaloric MUFA-rich diet prevents central fat redistribution and the postprandial decrease in peripheral adiponectin gene expression and insulin resistance induced by a CHO-rich diet in insulin-resistant subjects. Diabetes Care 30:1717-1723, 2007A positive energy balance, which leads to obesity, is associated with insulin resistance and an increased risk of type 2 diabetes. According to our studies in rodents, adipose tissue expandability seems to be a key determinant linking obesity and its associated complications (1,2). Expansion of the intra-abdominal depot has been associated with increased insulin resistance, as well as with an increased incidence of fatty liver and ␤-cell failure (3,4).The factors that regulate body fat distribution are not well understood. We hypothesize that the specific macronutrient composition of the diet may be an important environmental factor that controls nutrient partitioning to specific adipose tissue depots (5). It is now well established that adipose tissue is not simply an energy storage organ but is, in fact, the "largest" endocrine gland controlling energy homeostasis (6). It is conceivable that specific diet composition may directly influence the molecular events that govern gene expression in adipocytes (7), adipokine production, and adipocyte lipid and glucose metabolism (8).Adiponectin adipocyte-secreted adipokine plays an important role in modulating insulin sensitivity and concentrations of circulating plasma glucose and noneste...

Weight maintenance with a MUFA-rich diet improves HOMA-ir and fasting proinsulin levels in insulin-resistant subjects. Ingestion of a virgin olive oil-based breakfast decreased postprandial glucose and insulin concentrations, and increased HDL-C and GLP-1 concentrations as compared with CHO-rich diet.

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