The Effect of Pioglitazone and Resistance Training on Body Composition in Older Men and Women Undergoing Hypocaloric Weight Loss

Age-related increases in ectopic fat accumulation are associated with greater risk for metabolic and cardiovascular diseases, and physical disability. Reducing skeletal muscle fat and preserving lean tissue are associated with improved physical function in older adults. PPAR.-agonist treatment decreases abdominal visceral adipose tissue (VAT) and resistance training preserves lean tissue, but their effect on ectopic fat depots in nondiabetic overweight adults is unclear. We examined the influence of pioglitazone and resistance training on body composition in older (65-79 years) nondiabetic overweight/obese men (n = 48, BMI = 32.3 +/- 3.8 kg/m(2)) and women (n = 40, BMI = 33.3 +/- 4.9 kg/m(2)) during weight loss. All participants underwent a 16-week hypocaloric weight-loss program and were randomized to receive pioglitazone (30 mg/day) or no pioglitazone with or without resistance training, following a 2 x 2 factorial design. Regional body composition was measured at baseline and follow-up using computed tomography (CT). Lean mass was measured using dual X-ray absorptiometry. Men lost 6.6% and women lost 6.5% of initial body mass. The percent of fat loss varied across individual compartments. Men who were given pioglitazone lost more visceral abdominal fat than men who were not given pioglitazone (-1,160 vs. -647 cm(3), P = 0.007). Women who were given pioglitazone lost less thigh subcutaneous fat (-104 vs. -298 cm(3), P = 0.002). Pioglitazone did not affect any other outcomes. Resistance training diminished thigh muscle loss in men and women (resistance training vs. no resistance training men: -43 vs. -88 cm(3), P = 0.005; women: -34 vs. -59 cm(3), P = 0.04). In overweight/obese older men undergoing weight loss, pioglitazone increased visceral fat loss and resistance training reduced skeletal muscle loss. Additional studies are needed to clarify the observed gender differences and evaluate how these changes in body composition influence functional status.