Effects of short-term treatment with orlistat on growth hormone/insulin-like growth factor-I axis in obese post-menopausal women

Aim : Obesity is associated with an altered GH/IGF-I axis status, accounting for the increased cardiovascular risk in obese subjects with GH deficiency. Aim of this randomized, simple-blind, cross-over study was to verify the effectiveness of a short-term treatment with orlistat in reducing non-esterified fatty acid (NEFA) and influencing the endogenous activity of GH/IGF-I axis in obese subjects. Outcome measures : The primary outcome measures were post-prandial lipemia; GH peak after GHRH+arginine; IGF-I; IGF-binding protein (BP)-3, IGF-I/IGFBP-3 ratio. Secondary outcome measures were insulin resistance (IR) indexes (homeostasis model assessment of insulin resistance and Insulin Sensitivity Index). Study design : Twenty obese post-menopausal women (age: 53.6±6.2; body mass index: 34.1 ±4.0) were randomized to receive normo-caloric diet plus + orlistat (Roche, UK; 120 mg tid) or normo-caloric diet without the additional treatment. The duration of follow-up was 10 days for each treatment period. Results : Orlistat induced a weight-independent reduction in post-prandial NEFA levels compared with diet alone, with higher GH peak, IGF-I, and IGF-I/IGFBP3 ratio. GH peak was correlated negatively with postprandial NEFA and positively with IGF-I and IGF-I/IGFBP-3 ratio. Conclusions : Orlistat is effective in inducing a weight-independent higher reduction in post-prandial NEFA levels than dietary treatment alone along with increase in GH peak, IGF-I levels, and IGF-I/IGFBP-3 ratio. These results might add a new potential benefit of orlistat in the management of obese subjects.