Abstract
OBJECTIVE: To compare the effects of weight loss on visceral and subcutaneous abdominal fat, liver and pancreas lipid content and to test the effects of these changes on metabolic improvement observed after weight loss. DESIGN: Weight-loss program designed to achieve a loss of 7-10% of the initial weight. SUBJECTS: 24 obese subjects (13 males and 11 females) with age ranging from 26 to 69 years and body mass index (BMI) 30.2-50.5 kg m(-2). MEASUREMENTS: weight, BMI, waist circumference, body composition as assessed by dual-energy X-ray absorptiometry, metabolic variables, leptin, adiponectin, visceral and subcutaneous abdominal fat, liver and pancreas lipid content as assessed by magnetic resonance were evaluated before and after weight loss achieved by hypocaloric diet. RESULTS: After a mean body weight decrease of 8.9%, BMI, waist circumference, fat mass, all metabolic variables, homeostasis model assessment of insulin resistance (HOMA), alanine amino transferase, gamma glutamyl transpeptidase, high-sensitivity C-reactive protein (hs-CRP) and leptin, but not adiponectin and high-density lipoprotein-cholesterol, significantly decreased (all P<0.01). Visceral and subcutaneos abdominal fat, liver and pancreas lipid content significantly decreased (all P<0.01). Percent changes in liver lipid content were greater (84.1±3%) than those in lipid pancreas content (42.3±29%) and visceral abdominal fat (31.9±15.6%). After weight loss, percentage of subjects with liver steatosis decreased from 75 to 12.5%. Insulin resistance improvement was predicted by changes in liver lipid content independently of changes in visceral fat, pancreas lipid content, systemic inflammation, leptin and gender. CONCLUSION: Moderate weight loss determines significant decline in visceral abdominal fat, lipid content in liver and pancreas. Reduction of liver lipid content was greater than that of pancreas lipid content and visceral fat loss. Liver lipid content is the strongest predictor of insulin resistance improvement after weight loss.