Effects of a low-insulin-response, energy-restricted diet on weight loss and endocrinological parameter in obese, anovulatory women in their reproductive years

[摘要] There is consistent evidence that obese women are less fertile than women of normalbody weight. Obesity, in particular android obesity, is associated with several sexsteroid abnormalities in premenopausal women including: increased free estrogenand androgen fractions, reduced sex hormone-binding globulin and increased bioactiveestrogen delivery to target tissue.The state of insulin resistance with secondary hyperinsulinemia is commonlyobserved in obese, infertile women whereas the gonadotrophic effects of insulin onovarian steroid hormone synthesis have been indicated in vivo and in vitro. Insulin candirectly and indirectly stimulate ovarian androgen production. The exaggeratedinsulin action on ovarian tissues may present the pathological mechanism fordisturbances in the endocrine profile and menstrual cycle and infertility in some obesewomen.Due to certain limitations we did not diagnose anovulation whereas only a certainpercentage of the subjects in each group were hyperinsulinemic. One of the problemsexperienced was the drop outs in each group.Weight loss is associated with a significant improvement in menstrual abnormalities,ovulation and fertility rates with a reduction in hyperandrogenism andhyperinsulinemia. It is suggested that weight loss should be the first option in thetreatment of overweight infertile women. Intervention studies suggest that reducingweight and/or hyperinsulinemia either by diet alone or a combination of diet and drugtherapy should be investigated.This study was undertaken to evaluate the effects of a low-insulin-response, energyrestricteddiet (LID) on anthropometric and endocrinological parameters in obesewomen with menstrual abnormalities. For the purpose of this study we compared theeffects LID to a normal balanced-energy restricted diet. The principles for the LIDwere based on the available literature regarding the insulin response to foods and theircombinat ions. At baseline 37 candidates were randomly assigned into two groups. Group A followedthe LID and consisted of 19 candidates whereas Group B followed the NO andconsisted of 18 subjects. The inclusion criteria were: obese (BMI > 30kg/m2),premonopausal, insulin resistance, anovulation and between the ages of 18 and 04years of age whereas the exclusion criteria included increased fasting and stimulatedglucose concentrations, cigarette-smokers, and the presence of any chronic medicalcondition. Subject fasted for a 10 to 12 hour period after following a 250 gcarbohydrate diet for three-days prior to baseline blood sampling. Blood samples werecollected at baseline and at the end of the 16-week trial and analyzed for fastinginsulin and glucose, testosterone (T), luteinizing hormone (LH), follicle stimulatinghormone (FSH), estrogen (E), prolactin, thyroid stimulating hormone (TSH),thyroxine (FT4), leptin and progesterone. Insulin resistance were defined as aglucose-to-insulin ratio < 4.5. Stimulated 30 and 120-minute insulin and glucose werecollected after subjects consumed 82.5g of monohydrate glucose powder diluted in300ml water. Due to certain limitations we did not diagnose anovulation whereas only a certainpercentage of the subjects in each group were hyperinsulinemic. One of the problemsexperienced was the drop outs in each group. Results form this trial indicated a significant reduction in fasting and JO-minutestimulated insulin, LH, and testosterone and leptin concentrations in the NO groupwhereas only leptin concentrations reduced significantly in the LID group. Asignificant reduction occurred in mean weight, BMI, body fat percentage, waist andhip circumference in both groups. Numerous studies evaluated the effects of weight loss on fertility but to ourknowledge this is the first trial of its kind to evaluate the effects of two different testdiets on fertility parameters. Results from this trial confirm the positive effects ofweight loss on endocrinological and anthropometric parameters in obese women,however, the LID showed no beneficial effects over the NO. Future research isneeded to evaluate the effect of diet manipulation on fertility parameters with specificregard to diet manipulation in combination with drug therapy. This trial, however,serves as a good pilot study for future research of this kind.

[发布机构] University of the Free State