Substituting poly- and mono-unsaturated fat for dietary carbohydrate reduces hyperinsulinemia in women with polycystic ovary syndrome

Gynecol Endocrinol. 2017 Apr;33(4):324-327. doi: 10.1080/09513590.2016.1259407. Epub 2016 Dec 2.


Objective: Hyperinsulinemia is a prevalent feature of polycystic ovary syndrome (PCOS), contributing to metabolic and reproductive manifestations of the syndrome. Weight loss reduces hyperinsulinemia but weight regain is the norm, thus preventing long-term benefits. In the absence of weight loss, replacement of dietary carbohydrate (CHO) with mono/polyunsaturated fat reduces ambient insulin concentrations in non-PCOS subjects. The current study evaluated whether this dietary intervention could ameliorate hyperinsulinemia in women with PCOS.

Design/setting/patients: Obese women with PCOS (BMI 39 ± 7 kg/m2) and insulin resistance completed a crossover study (Stanford University Clinical Research Center) comparing two isocaloric diets, prepared by research dietitians, containing 60% CHO/25% fat versus 40% CHO/45% fat (both 15% protein and ≤7% saturated fat). After 3 weeks on each diet, daylong glucose, insulin, and fasting lipid/lipoproteins were measured.

Results: Daylong glucose did not differ according to diet. Daylong insulin concentrations were substantially (30%) and significantly lower on the low CHO/higher fat diet. Beneficial changes in lipid profile were also observed.

Conclusions: Replacement of dietary CHO with mono/polyunsaturated fat yields clinically important reductions in daylong insulin concentrations, without adversely affecting lipid profile in obese, insulin-resistant women with PCOS. This simple and safe dietary intervention may constitute an important treatment for PCOS. Identifier: NCT00186459.

Keywords: Carbohydrate; PCOS; diet; insulin; insulin-resistant; obesity.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • Cross-Over Studies
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Fats, Unsaturated / administration & dosage*
  • Female
  • Humans
  • Hyperinsulinism / blood
  • Hyperinsulinism / diet therapy*
  • Insulin / blood*
  • Insulin Resistance / physiology*
  • Lipids / blood
  • Obesity / blood
  • Polycystic Ovary Syndrome / blood
  • Polycystic Ovary Syndrome / diet therapy*
  • Treatment Outcome
  • Young Adult


  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats, Unsaturated
  • Insulin
  • Lipids

Associated data