Short-term effects of a hypocaloric diet with low glycemic index and low glycemic load on body adiposity, metabolic variables, ghrelin, leptin, and pregnancy rate in overweight and obese infertile women: a randomized controlled trial

Background: Obesity is related to hormonal disorders that affect the reproductive system. Low-glycemic index (LGI) diets seem to exert a positive effect on weight loss and on metabolic changes that result from obesity. Objective: We investigated the effects of a hypocaloric diet with an LGI and low glycemic load on anthropometric and metabolic variables, ghrelin and leptin concentrations, and the pregnancy rate in overweight and obese infertile women who were undergoing in vitro fertilization (IVF). Design: The study was a randomized block-design controlled trial in which we analyzed 26 overweight or obese infertile women. Patients were assigned to a hypocaloric LGI-diet group or a control group and followed the protocol for 12 wk. Body weight, body mass index (BMI), percentage of body fat, glucose, insulin, homeostasis model assessment of insulin resistance, serum lipids, reproductive hormones, leptin, acylated ghrelin, number of oocytes retrieved in the IVF cycle, and pregnancy rate were determined. Results: There were greater reductions in body mass, BMI, percentage of body fat, waist: hip ratio, and leptin in the LGI-diet group than in the control group (P < 0.05). Despite a change of 18% in mean values, there was no significant increase in acylated ghrelin concentrations in the LGI group compared with the control group (P = 0.215). The LGI-diet group had 85.4% more oocytes retrieved than did the control group (7.75 +/- 1.44 and 4.18 +/- 0.87, respectively; P = 0.039) in the IVF cycle. Three patients (21.4%) in the LGI group experienced a spontaneous pregnancy during the follow-up, which generated 3 live births. Conclusions: The hypocaloric LGI diet promoted a decrease in BMI, percentage of body fat, and leptin concentrations, which improved oocyte development and pregnancy rate. These results support the clinical recommendation to advise overweight and obese women to lose weight through a balanced diet before being submitted for treatment with assisted reproduction technologies. A hypocaloric diet combined with LGI foods seems to be beneficial for these patients, but additional studies are required before this treatment is recommended.