Effect of a low insulinemic diet on clinical, biochemical and metabolic outcomes in women with polycystic ovary syndrome (PCOS)

The objective of this study was to determine whether a low insulinemic diet would improve anthropometric, biochemical, and metabolic outcome measures, as well as binge eating behaviors and health-related quality-of-life in women with PCOS. A low insulinemic diet was chosen versus a low glycemic diet due to emerging research indicating dissociation between glycemic and insulinemic responses to certain foods, such as starch and dairy.
Women with PCOS (n = 24) between 18–45 years (BMI ≥25kg/m2 and ≤45 kg/m2) participated in an 8-week dietary intervention trial. Diagnosis of PCOS was based on oligo- and/or amenorrhea, presence of hyperandrogenism, and/or presence of polycystic ovaries by ultrasound. Women were asked to discontinue insulin sensitizers, oral contraceptives, and cyclic progesterone prior to the 8-week study. Ten of the 24 participants underwent metabolic testing using a metabolic cart to analyze fasting and postprandial energy expenditure, respiratory exchange ratio (RER), and macronutrient oxidation after consuming a high-saturated fat shake. Women experienced a significant reduction in weight (p < 0.0001), BMI (p < 0.0001), fat mass (p = 0.02), hip circumference (p < 0.0001), waist circumference (p < 0.0001), fasting and 2-hr insulin levels (p < 0.0001 and p < 0.03, respectively), triglycerides (p < 0.0001), VLDL (p < 0.0001), free testosterone (p < 0.05), total testosterone (p < 0.01), and vitamin D (p < 0.01). HDL was significantly decreased (p < 0.01). There was also a significant reduction in RER and carbohydrate oxidation, and a significant increase in fat oxidation from pre- to post-diet after adjustment for body weight in kilograms. Binge eating scores and quality of life measurements measured were measured by the Binge Eating Scale (BES) and PCOS specific questionnaire (PCOSQ) and were also significantly (p < 0.05) improved. The low insulinemic diet significantly improved anthropometric, biochemical, and metabolic outcome measures in women with PCOS. Participants also had significantly improved scores on the BES and PCOSQ indicating improved eating behaviors and quality of life measures after the 8-week dietary intervention. Considering the chronic disease risks and psychological stress associated with PCOS, the reduction in weight, insulin sensitivity, blood lipids, serum testosterone, and improvement in eating behaviors and quality of life is promising.