Low-glycemic Load vs. Low-fat Diet for Treating PCOS in Obese Adolescents and Young Adults

Background. The polycystic ovary syndrome (PCOS) is a complex hormonal disorder that presents in susceptible girls around the time of menarche. Females with PCOS have high levels of androgens (e.g., testosterone). While cosmetic appearance (excess facial hair and acne) and menstrual disturbances were once considered the primary concerns, emerging data indicate that many adolescents and young adults with PCOS are insulin resistant and at increased risk for metabolic syndrome and diabetes. The majority of females with PCOS are obese, and excess body fat amplifies the severity of the syndrome.

Dietary intervention is considered an important component of treatment for PCOS. However, a consensus statement regarding optimal nutrient composition for treating adolescents and young adults with PCOS has not been published because data are lacking to provide a foundation for such a statement. Recognizing increased risk for diabetes in patients with PCOS, many practitioners employ a low-fat diet as prescribed in the Diabetes Prevention Program (DPP) for weight loss and control of symptoms.

Objective and Hypothesis. The purpose of this research study is to compare different diets for treating PCOS. We hypothesize that a low-glycemic load diet - designed to lower blood levels of glucose and insulin - will be more beneficial than a low-fat diet in obese adolescents and young adults with PCOS.

Design. We propose a 6-month study in which 50 obese females with PCOS (ages 13 to 21 years) will be assigned to receive one of two dietary treatments, with the goal of retaining 40 participants. Group assignment will be at random. One of the treatments will be a low-glycemic load diet, and the other treatment will be a low-fat diet (modeled after the DPP diet). Participants in both groups will receive individual nutrition education and dietary counseling with a registered dietitian (clinic visits, telephone calls) and cooking workshops with a chef. The purpose of the cooking workshops will be to enhance compliance with diet prescriptions, beyond what can be achieved by nutrition education and dietary counseling in a conventional clinic setting.

The primary outcome will be bioavailable testosterone (form of testosterone that causes symptoms of PCOS). Secondary outcomes will include other blood tests to evaluate further high androgen levels (total testosterone, free testosterone, sex hormone binding globulin, dehydroepiandrosterone sulfate), clinical signs of high androgen levels (excess facial hair, acne), glucose tolerance and risk for diabetes (determined by blood sugar and insulin measurements), risk for cardiovascular disease (based on blood cholesterol and C-reactive protein levels and blood pressure), body fat percentage and distribution (measured using state-of-the-art dual energy x-ray absorptiometry and waist circumference), menstrual cyclicity, and health-related quality of life (evaluated by questionnaire).