Journal Article

Effect of Calorie Restriction With or Without Exercise on Insulin Sensitivity, Β-Cell Function, Fat Cell Size, and Ectopic Lipid in Overweight Subjects

Anton, Steve, Larson-Meyer, D. Enette, Heilbronn, Leonie K, Smith, Steven R, Alfonso, Anthony, Redman, Leanne M, Frisard, Madlyn I, Ravussin, Eric, Newcomer, Bradley R

2006

Overview

OBJECTIVE:--The purpose of this article was to determine the relationships among total body fat, visceral adipose tissue (VAT), fat cell size (FCS), ectopic fat deposition in liver (intrahepatic lipid [IHL]) and muscle (intramyocellular lipid [IMCL]), and insulin sensitivity index (Si) in healthy overweight, glucose-tolerant subjects and the effects of calorie restriction by diet alone or in conjunction with exercise on these variables. RESEARCH DESIGN AND METHODS--Forty-eight overweight volunteers were randomly assigned to four groups: control (100% of energy requirements), 25% calorie restriction (CR), 12.5% calorie restriction +12.5% energy expenditure through structured exercise (CREX), or 15% weight loss by a low-calorie diet followed by weight maintenance for 6 months (LCD). Weight, percent body fat, VAT, IMCL, IHL, FCS, and Si were assessed at baseline and month 6. RESULTS:--At baseline, FCS was related to VAT and IHL (P < 0.05) but not to IMCL. FCS was also the strongest determinant of Si (P < 0.01). Weight loss at month 6 was 1 ± 1% (control, mean ± SE), 10 ± 1% (CR), 10 ± 1% (CREX), and 14 ± 1% (LCD). VAT, FCS, percent body fat, and IHL were reduced in the three intervention groups (P < 0.01), but IMCL was unchanged. Si was increased at month 6 (P = 0.05) in the CREX (37 ± 18%) and LCD (70 ± 34%) groups (P < 0.05) and tended to increase in the CR group (40 ± 20%, P = 0.08). Together the improvements in Si were related to loss in weight, fat mass, and VAT, but not IHL, IMCL, or FCS. CONCLUSIONS:--Large adipocytes lead to lipid deposition in visceral and hepatic tissues, promoting insulin resistance. Calorie restriction by diet alone or with exercise reverses this trend.

• Publisher: American Diabetes Association
• Subject: adipocytes / adipose tissue / Adipose Tissue - pathology / Basal Metabolism / Biological and medical sciences / body fat / Body Mass Index / Body Weight / Cell Size / Diabetes / Diabetes. Impaired glucose tolerance / Diet, Reducing / Endocrine pancreas. Apud cells (diseases) / Endocrinopathies / energy expenditure / Energy Metabolism / energy requirements / Exercise / Health aspects / Humans / Insulin / Insulin - physiology / insulin resistance / Islets of Langerhans - physiopathology / Lipids - blood / liver / low calorie diet / Medical sciences / Metabolic diseases / Obesity / Overweight / Risk factors / Viscera / volunteers / weight control / weight loss