PCOS, or polycystic ovarian syndrome, is a common condition characterized by signs and symptoms of high testosterone, insulin resistance, irregular or absent periods, abnormal hair growth (hirsutism), acne, fertility difficulties, and ovarian cysts.

One of the primary approaches to PCOS includes controlling insulin which conventionally includes a prescription for metformin. Whether you go this route, are using natural alternatives to improve insulin sensitivity, or are treating 100% through lifestyle changes, it’s crucial to support healthy glucose and insulin through nutrition and exercise.

The primary dietary techniques for conditions involving high blood sugar or insulin resistance like PCOS are a low carbohydrate diet, or in some cases, a more restricted ketogenic diet.

What is the ketogenic diet?

The ketogenic diet is a very low carb, high fat, and moderate protein diet. By consuming so few carbohydrates your body is forced to switch to a physiological state known as “ketosis” where your body changes its fuel source. Blood glucose (or blood sugar) levels fall and your body can no longer rely on this glucose for fuel. Your body then turns to fatty acids. These fatty acids are your body’s storage form of fuel which is then broken down into ketone bodies which are used similarly to glucose.

What improvements can the ketogenic diet have on PCOS?

Studies have shown that the ketogenic diet can help reduce Hemoglobin A1c (a blood marker associated with diabetes), (1) improve weight loss, decrease free testosterone, improve fasting insulin, (2) (3) HOMA-IR (insulin resistance marker), hs C-reactive protein (inflammation marker), and adiponectin (fat hormone). (4) (5) The ketogenic diet has also been shown to improve psychological conditions like depression and quality of life in people with PCOS. (6)

Can the ketogenic diet help improve fertility in PCOS?

It is possible that the ketogenic diet could improve fertility for some patients with PCOS. Studies have shown an improvement in ovulatory function, LH/FSH ratio, and pregnancy in PCOS with the ketogenic diet. This is likely due to improvement in insulin leading to improvement in hormone imbalance such as increased sex hormone binding globulin (SHBG). Higher levels of SHBG helps bind more free testosterone, reducing its effect in the body and thus improving ovulation.

In a prospective study of over 18,000 women, ovulatory infertility was 78% higher in women consuming a higher carbohydrate diet compared to those eating a low carb diet. (7) So even if the ketogenic diet is not done, a low carb diet would likely be more beneficial in PCOS than a high carb diet for improving fertility outcomes.

Would keto be beneficial for people with “lean PCOS”?

Even patients with lean PCOS, when weight gain/obesity is not an issue, insulin resistance can still be at the root of hormone imbalance. People with lean PCOS may have intrinsic insulin resistance and can have more visceral fat than similar BMI counterparts. Visceral fat is fat that surrounds organs like your liver and is generally associated with metabolic conditions including blood sugar dysregulation/insulin resistance.

A study done in March 2019 showed 43.7% reduced visceral fat after implementing the ketogenic over a 12-week period. (8)

What are the drawbacks of keto?

It is possible to have side effects from the ketogenic diet, especially when starting out. Common side effects are constipation, dizziness, and fatigue, though many of these can be avoided. For patients who are doing the ketogenic diet long term I recommend monitoring cholesterol levels that include markers like particle number and size, electrolytes, magnesium, and other nutrients. Though keto can sometimes increase cholesterol, often there are improvements in many cardiovascular risk markers such as HDL (good cholesterol), triglycerides, LDL particle number, TNF-α, hs-CRP, and Lp(a). LDL (bad cholesterol) can sometimes increase or decrease. (5) Due to the nuances of doing the ketogenic diet properly and to avoid side effects, talk to your healthcare provider to determine if this is a good option for you.

Works Cited

1. Ketogenic Diet and its Evidence-Based Therapeutic Implementation in Endocrine Diseaeses. Stocker, RK, et al. 8, Bern : Praxis, 1994, Vol. 108, pp. 541-553.

2. The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: a pilot study. Mavropoulos, JC, et al. 2, London : Nutr Metab, 2005, Vol. 16, p. 35.

3. Treatment of obesity in polycystic ovary syndrome: a position statement of the Androgen Excess and Polycystic Ovary Syndrome Society. Moran, LJ, et al. 6, s.l. : Fertil Steril, 2009, Vol. 92, pp. 1966-82.

4. Metabolic impact of ketogenic diet compared to a hypocaloric diet in obese children and adolescents. Partsalaki, I, Karvela, A and Spiliotis, BE. 7, s.l. : J Pediatr Endocrinol Metab, 2012, Vol. 25, pp. 697-704.

5. Effects of a carbohydrate-restricted diet on emerging plasma markers for cardiovascular disease. Wood, R, et al. 19, London : Nutr Metab , 2006, Vol. 3.

6. Lifestyle management improves quality of life and depression in overweight and obese women with polycystic ovary syndrome. Thomson, RL, et al. 5, s.l. : Fertil Steril, 2010, Vol. 94, pp. 1812-6.

7. Body mass index and short-term weight change in relation to treatment outcomes in women undergoing assisted reproduction. Chavarro, JE, et al. 1, s.l. : Fertil Steril, 2012, Vol. 98, pp. 109-16.

8. Extended ketogenic diet and physical training intervention in military personnel. LaFountain, RA. s.l. : Mil Med, March 16, 2019.