Deep Dive: Low glycemic index diets for PCOS. Do they work?

Polycystic ovary syndrome^[1] (PCOS) is an endocrine and reproductive disorder characterized by an excess of hormones that regulate male characteristics (androgens) and ovulatory dysfunction. It affects about 6–20% of pre-menopausal women (depending on how it’s defined; see the sidebar below for more info on the definition of PCOS) and is associated with insulin resistance, dyslipidemia, and visceral adiposity^[2] (fat that surrounds vital organs like the liver and intestines). Some of the metabolic consequences of PCOS are depicted in Figure 1.

Figure 1: The metabolic consequences of PCOS

Adapted from: Escobar-Morreale. Nat Rev Endocrinol. 2018 May.^[1]

There is no universal treatment for PCOS. Since PCOS affects endocrine, reproductive, and, ultimately, metabolic health, treatment is individualized to the needs of the patient following first-line therapy^[3] that involves lifestyle, diet, and/or exercise modifications. However, beyond energy restriction, no consensus exists for specific PCOS dietary guidelines, as research is quite scarce for this common, yet often scientifically-neglected, condition.

Low glycemic index (LGI) diets focus on foods that have a minor effect on blood sugar levels, even though they may include a considerable amount of carbohydrates. Adherence to such diets can not only benefit blood sugar control^[4], but also various cardiovascular and metabolic health^[5] measures in non-PCOS populations. The purported benefits of LGI diets overlap with PCOS pathophysiology. Some studies evaluating the relationship report promising^[6] results^[7]. However, conflicting results^[7] have also been reported^[8], making it difficult to determine whether LGI diets would be a generally useful treatment option.

The authors of the study under review designed a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine whether LGI diets might improve cardiometabolic and reproductive health measures in women with PCOS.

PCOS is an endocrine and reproductive disorder associated with metabolic dysregulation. LGI diets benefit glucoregulation and cardiometabolic health in non-PCOS populations, but results in PCOS populations report mixed results. The authors of the study under review designed a systematic review and meta-analysis to determine whether LGI diets might improve cardiometabolic and reproductive health measures in women with PCOS.