Effects of an Energy-Restrictive Diet With or Without Exercise on Abdominal Fat, Intermuscular Fat, and Metabolic Risk Factors in Obese Women

Abstract

OBJECTIVE—The primary objective was to examine whether the combination of diet and aerobic exercise (DA) or diet and resistance exercise (DR) is associated with greater improvements in metabolic risk factors by comparison to diet only (DO) in obese women. A second objective considered whether reductions in metabolic risk factors are related to concurrent changes in abdominal and/or intermuscular fat distribution. RESEARCH DESIGN AND METHODS—A total of 38 premenopausal obese women were randomly assigned to one of three 16-week treatments: DO (n=13), DA (n=11), or DR (n=14). Plasma glucose, insulin, and lipid levels were measured in a fasting state and after a 75-g oral glucose challenge (oral glucose tolerance test [OGTT]). Total, abdominal subcutaneous, visceral, and intermuscular fat were measured by magnetic resonance imaging. RESULTS—Significant reductions (P < 0.02) in body weight (∼10 kg or 10%) and in total, abdominal subcutaneous, visceral, and intermuscular fat were observed within each group. Fasting and OGTT insulin, total cholesterol, LDL cholesterol, and apolipoprotein B also decreased within each group (P ≤ 0.02). The changes in the body fat and metabolic variables were not different across treatment (P > 0.05). Visceral fat alone was related to the metabolic risk factors both before and after the treatment. CONCLUSIONS—Weight loss was associated with reductions in metabolic risk factors in obese women. The improvement in the metabolic profile was not enhanced by the addition of aerobic or resistance exercise. The findings reinforce the importance of diminished visceral fat in the treatment of insulin resistance.