For women diagnosed with Polycystic Ovary Syndrome (PCOS) obesity is a big issue. Losing weight and maintaining a healthy body weight is highly recommended because it helps reduce all other symptoms, one of which is high insulin resistance. Doctors have recommended a low glycemic (low-GI) diet (the recommended diet for diabetics) without a lot of real clinical evidence. However a study published in The American Journal of Clinical Nutrition compares the a low-GI diet to a conventional healthy diet and how each diet effects weight loss, insulin tolerance, and other symptoms in overweight and obese women with PCOS. Participants on the low-GI diet lost more body weight and improved in insulin tolerance while those on a regular conventional diet lost less body weight and no improvement in insulin tolerance was found. This paper supports the findings in this study that a low-GI diet is a more effective diet overall for women with PCOS than a regular conventional diet.1
The study subjects chosen were women who had PCOS. They had to be premenopausal and either overweight or obese. 96 women were chosen. They were randomly chosen to follow either a low-GI diet or a conventional healthy diet. 50 were assigned to the low-GI diet and 46 to the conventional healthy diet. The diets were the same with fat and protein levels. The only difference was the low-GI diet participants consumed low-GI foods and the conventional diet participants consumed medium or high GI foods. Only 29 participants on the low-GI diet and 20 on the conventional diet completed the study. These women were followed for 12 months or until they achieved a 7% weight loss (whichever came first). Information was gathered before and after completion of the study. Weight loss, insulin sensitivity, glucose tolerance and other categories were tested. In the low-GI diet the mean weight loss was 5.2% and in the conventional diet weight loss was 4.2%. The low-GI diet group showed a significant increase in insulin sensitivity (2.2; P < 0.01) while the conventional diet showed no significant increase (0.7; P = 0.2). Homeostasis was significantly affected. In the low-GI group fibrinogen concentrations fell (-0.2 g/L) while they increased in the conventional group (0.2 g/L). The effects on menstrual cyclicity were also significant. Those participants with irregular cycles showed 95% increase in menstrual regularity for the low-GI group and 63% for the conventional group. The other findings weren’t found to be overall significant.
The findings of this study show evidence that the low-GI diet is overall more beneficial for women with PCOS than is the conventional healthy diet. Insulin tolerance and menstrual regularity especially effected. This study shows a great start to proving whether or not a low-GI diet is more beneficial for women with PCOS it has some weaknesses. The number of study subjects that actually completed the study was very small. A study with a greater number of test subjects would help show the significance of these findings. This study is a good start to helping women with PCOS know what diet is most beneficial however more studies need to be done in order to solidify these findings.
Other studies and research have been done on diet and how it affects women with PCOS. One study showed that fasting insulin levels were lower when subjects were following a low-GI diet as compared to a standard diet with 55% carbohydrates. The conclusion was that a low-GI diet was beneficial for insulin levels but no significant findings were found with metabolic and endocrine characteristics.2 A. Tolino et al had participants follow a calorie-restricted diet. The restrictions were based on the test subject’s BMI. Findings showed that a weight loss of 5% or more in women with PCOS showed an increase in reproductive function and significant improvement in insulin resistance and insulin levels in the blood.3 A study done by S. Barr et al had interesting findings. Women with PCOS followed a low-GI diet, but were not asked to make any other lifestyle changes (exercise improvement, etc.). Insulin sensitivity increased significantly however no significant change in body weight was found.4
In conclusion this article has evidence of the benefits of a low-GI diet for women with PCOS however the small study group size makes its findings somewhat questionable. It does however show that further research would be beneficial. Following a low-GI diet would not do any harm to women with PCOS. As such it would be beneficial to follow a low-GI diet to see if any significant changes occur.
1. Marsh K A, Steinbeck K S, Atkinson F S, Petocz P, Brand-Miller J C. Effect of a low glycemic index compared with a conventional healthy diet on polycystic ovary syndrome. Am J Clin Nutr. 2010; 92:83-92.
2. Kathleen M. Hoeger. Obesity and lifestyle management in polycystic ovary syndrome. Clin Obstet Gynecol. 2007; 50(1): 277-294.
3. Tolino A, Gambardella V, Caccavale C, et al. Evaluation of ovarian functionality after dietary treatment in obese women with polycystic ovary syndrome. Eur J Obstet Gyn R B. 2005; 119(1): 87-93.
4. Barr S, Reeves S, Sharp K, Jeanes Y M. An isocaloric low glycemic index diet improves insulin sensitivity in women with polycystic ovary syndrome. J Acad Nutr Diet. 2013; 113(11): 1523-1531.
Reviewed by Viktoriya Wolff