Recombinant human growth hormone, but not insulin-like growth factor-I, enhances central fat loss in postmenopausal women undergoing a diet and exercise program

We examined the effect of recombinant human growth hormone (rhGH) and/or re combinant human insulin-like growth factor-I (rhIGF-I) on regional fat loss in postmenopausal women undergoing a weight loss regimen of diet plus exer cise. Twenty-seven women aged 59-79 years, 20-40% above ideal body weight, completed a 12-week program consisting of resistance training 2 days/week a nd walking 3 days/week, while consuming a diet that was 500 kcal/day less t han that required for weight maintenance, Participants were randomly assign ed in a double-blind fashion to receive rhGH (0.025 mg/kg BW/day: n=7), rhI GF-I (0.015 mg/kg BW/day: n=7), rhGH + rhIGF-I (n = 6), or placebo (PL: n = 7). Regional and whole body fat mass were determined by dual X-ray absorpt iometry. Body fat distribution was assessed by the ratios of trunk fat-to-l imb fat (TrF/LimbF) and trunk fat-to-total fat (TrF/TotF), Limb and trunk f at decreased in all groups (p < 0.01). For both ratios of fat distribution, the rhGH treated group experienced an enhanced loss of truncal compared to peripheral fat (p less than or equal to 0.01), with no significant change for those administered rhIGF-I or FL. There was no association between chan ge in fat distribution and indices of cardiovascular disease risk as determ ined by serum lipid/lipoprotein levels and maximal aerobic capacity. These results suggest that administration of rhGH facilitates a decrease in centr al compared to peripheral fat in older women undertaking a weight loss prog ram that combines exercise and moderate caloric restriction, although no be neficial effects are conferred to lipid/lipoprotein profiles, Further, the effect of rhGH is not enhanced by combining rhCH with rhIGF-I administratio n. In addition, rhIGF-I does not augment the loss of trunk fat when adminis tered alone.