Effect of a low glycemic index compared with a conventional healthy diet on polycystic ovary syndrome

Am J Clin Nutr. 2010 Jul;92(1):83-92. doi: 10.3945/ajcn.2010.29261. Epub 2010 May 19.


Background: Women with polycystic ovarian syndrome (PCOS) are intrinsically insulin resistant and have a high risk of cardiovascular disease and type 2 diabetes. Weight loss improves risk factors, but the optimal diet composition is unknown. Low-glycemic index (low-GI) diets are recommended without evidence of their clinical effectiveness.

Objective: We compared changes in insulin sensitivity and clinical outcomes after similar weight losses after consumption of a low-GI diet compared with a conventional healthy diet in women with PCOS.

Design: We assigned overweight and obese premenopausal women with PCOS (n = 96) to consume either an ad libitum low-GI diet or a macronutrient-matched healthy diet and followed the women for 12 mo or until they achieved a 7% weight loss. We compared changes in whole-body insulin sensitivity, which we assessed using the insulin sensitivity index derived from the oral-glucose-tolerance test (ISI(OGTT)); glucose tolerance; body composition; plasma lipids; reproductive hormones; health-related quality of life; and menstrual cycle regularity.

Results: The attrition rate was high in both groups (49%). Among completers, ISI(OGTT) improved more with the low-GI diet than with the conventional healthy diet (mean +/- SEM: 2.2 +/- 0.7 compared with 0.7 +/- 0.6, respectively; P = 0.03). There was a significant diet-metformin interaction (P = 0.048), with greater improvement in ISI(OGTT) among women prescribed both metformin and the low-GI diet. Compared with women who consumed the conventional healthy diet, more women who consumed the low-GI diet showed improved menstrual cyclicity (95% compared with 63%, respectively; P = 0.03). Among the biochemical measures, only serum fibrinogen concentrations showed significant differences between diets (P < 0.05).

Conclusion: To the best of our knowledge, this study provides the first objective evidence to justify the use of low-GI diets in the management of PCOS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Blood Glucose / metabolism*
  • Body Composition
  • Body Mass Index
  • Cardiovascular Diseases / epidemiology
  • Cardiovascular Diseases / etiology
  • Diet*
  • Female
  • Fertilization in Vitro
  • Glycemic Index*
  • Humans
  • Hypoglycemia
  • Hypoglycemic Agents / therapeutic use
  • Metformin / therapeutic use
  • Overweight / blood*
  • Overweight / diet therapy
  • Polycystic Ovary Syndrome / blood*
  • Polycystic Ovary Syndrome / complications
  • Polycystic Ovary Syndrome / drug therapy
  • Polycystic Ovary Syndrome / physiopathology
  • Pregnancy
  • Risk Reduction Behavior
  • Weight Loss


  • Blood Glucose
  • Hypoglycemic Agents
  • Metformin