This post was updated on August 31st, 2022

By Kym Campbell, BSc. | Updated August 31st, 2022

Medically Reviewed by Dr. Sarah Lee, M.D & Dr. Jessica A McCoy, Ph.D

The ketogenic diet has become popular among women with polycystic ovary syndrome (PCOS). But appearances can be misleading.

There’s growing evidence showing that a keto diet may be good for some women, some of the time. But a misunderstanding of the nuances of this diet can potentially cause more harm than good.

PCOS is driven by a combination of high carbohydrate intake, low-grade inflammation, insulin resistance, and elevated androgen levels [1]. Since the ketogenic diet removes almost all dietary carbohydrates, it can significantly improve the pathology of this syndrome.

But effective doesn’t always mean safe or optimal. Other alternatives, like the diet we use in my free 30-Day PCOS Diet Challenge, may be more suitable. I explain this more below.

This article takes a deep dive into the pros and cons of the keto diet for PCOS. The information provided will help you decide if this dietary intervention is right for you.

1. Pro: Improves Insulin Resistance

Best estimates suggest insulin resistance affects between 30 and 70% of women with PCOS [2, 3]. The severity of insulin resistance largely determines the strength of PCOS symptoms.

Insulin resistance is a known risk factor for type 2 diabetes, liver disease, heart attack, and stroke. In women with PCOS, insulin resistance contributes to menstrual irregularities and infertility [4]. Studies also show that insulin is associated with depression [5].

A ketogenic diet improves PCOS by reversing the effects of insulin resistance. Carbohydrate intake is restricted to the point that there isn’t enough glucose to meet the body’s energy requirements. The body then switches to burning fat by-products (ketones) instead of glucose. This lowers insulin levels and the negative effects of insulin resistance [6, 7].

Ketosis can be a powerful way to reduce body fat. For overweight women with PCOS, this can help with weight loss, irregular periods, unwanted body hair, high blood pressure, and more.

2. Pro: Sex Hormones, Metabolic Health, & Body Composition

Within the scientific community, the benefits of a keto diet for PCOS are unclear. The size, duration, or other confounding factors limit the clinical significance of the findings. Despite these constraints, there are still several pilot studies that show positive results.

  • Mavropoulos et al. 2005 [8] studied 5 women over 6 months. They saw both weight loss and improvements in sex hormone imbalances.
  • Paoli et al. 2020 [9] studied 14 women over 12 weeks. They observed improvements in body composition, sex hormone imbalances, and insulin regulation. Triglyceride and cholesterol levels also improved. This study restricted caloric intake to 1600 kcal per day.
  • Cincione et al. 2021 [10] studied 17 women over 45 days. They observed improvements in multiple biochemical parameters such as LH, FSH, SHBG, and insulin sensitivity. Patients lost 12.4 lb (5.6 kg) on average and showed other improvements in markers of body composition (waist and hip circumference, etc.). It should be noted that this study also restricted caloric intake to just 600 kcal per day. An exceptionally low caloric intake by any measure. This last point is often missed by people referencing the Cincione et al. study.

The participants in these studies were between the ages of 18 and 45. They were diagnosed with PCOS, and had a BMI > 25 kg/m2 – this is within the overweight range. They were not pregnant or breastfeeding, and they had no other serious medical conditions.

When looking at ketogenic diet studies, it’s important to look at the characteristics of the participants. This can have a significant impact on the applicability of the results. Sex, body weight, age, and health status all impact the risks and benefits of a ketogenic diet. Not all keto studies can be generalized for PCOS, so caution is warranted when assessing the pros and cons.

For example, some experts are open to using a well-formulated ketogenic diet as a first-line treatment for obesity and diabetes [11]. For women with PCOS more generally though, others urge greater caution.

According to Dr. Jennifer T. Batch M.D and colleagues, the benefits of a ketogenic diet are generally not seen beyond 12 months. The impact on fertility is unclear, and the long-term implications are not well-understood. For example, Batch points out that despite the diet’s favorable effect on HDL-cholesterol levels, increases in very-low-density LDL may increase cardiovascular risks [6].

3. Con: It’s Not Tailored For PCOS

Given that the only rule of a ketogenic diet is to reach nutritional ketosis, it’s easy to see the shortcomings in this approach. A diet that’s designed with PCOS in mind is likely to be more suitable.

For example, a ketogenic diet provides no guidance on the suitability of gluten or dairy beyond their impact on ketosis. It’s common for women with PCOS to have a subclinical intolerance to gluten and dairy proteins. This means that these ingredients are generally best avoided. When left undiagnosed, a gluten or dairy sensitivity can undermine the intestinal wall lining. This causes inflammation [12]. Low-grade chronic inflammation is a key mechanism in the pathology of PCOS. Because of this, including gluten and dairy in a ketogenic diet can be counter-productive.

Sometimes referred to as “junk keto”, processed, and pro-inflammatory foods are also allowed on a keto diet. Vegetable oils, processed meats, and artificial sweeteners are acceptable. Yet, these are all foods to avoid with PCOS.

In isolation, each dietary change has a small effect. But a holistic PCOS diet can lead to life-changing results. This is what my free 30-Day PCOS Diet Challenge is all about. The results speak for themselves.

4. Con: May Cause Nutrient Deficiencies

One of the least disputed drawbacks of the ketogenic diet is its lack of nutritional balance.

The ketogenic diet is nutritionally imbalanced. It has the potential to cause vitamin and mineral deficiencies that include calcium, phosphorus, magnesium, and selenium [13, 14].

The study by Cincione et al. 2021, cited above, issued multivitamin and multimineral supplements to avoid this very problem.

Women with PCOS already have elevated risks for various deficiencies. For example, this is a known risk when using birth control for PCOS. With this in mind, a ketogenic diet can make matters worse.

5. Con: It’s Hard On Gut Health

Another key problem with the ketogenic diet is its effects on the gut microbiome. It’s common for people following a keto diet to consume inadequate amounts of fermentable, prebiotic fibers. This includes things like pectin, inulin, and oligofructose. This is because we usually get these important nutrients from fruits, starchy vegetables, and legumes. But with a ketogenic diet, these foods all need to be restricted because of their carbohydrate content.

Experienced clinicians have noticed that patients following a ketogenic diet, often experience gut dysbiosis. They speculate that this could open the door for pathogens to colonize the gut. Recent evidence has also linked a diet low in fermentable fibers to inflammatory diseases like PCOS [15].

6. Con: Can Be Psychologically Unhealthy

Leaving health and fertility aside, maintaining nutritional ketosis can be psychologically difficult. Disordered eating affects women with PCOS roughly five times as much as the general population. Eating disorders are especially likely if they also suffer from anxiety or depression [16]. Given that severe carbohydrate restriction is necessary to maintain nutritional ketosis, a ketogenic diet may further deteriorate an already tenuous relationship with food.

7. Con: Harder To Follow For PCOS Women

PCOS may also make it harder to follow a ketogenic diet.

The hormone dysregulation that characterizes PCOS is associated with increased appetite, impaired impulse control, and feelings of body dissatisfaction. These physiological effects commonly lead to binge eating [17]. Since even modest over-consumption of carbohydrates can break ketosis, the hormone dysregulation caused by PCOS may undermine the efficacy of the diet.

8. Con: Ketosis Can Make PCOS Worse

Evidence suggests that the keto diet may be beneficial in the short term. But a ketogenic diet can make PCOS worse over the long term:

  • 45% of adolescent females reported menstrual dysfunction after following a ketogenic diet [18]. Menstrual dysfunction is a known side-effect of ketosis.
  • Overly restricting carbohydrate consumption may negatively impact thyroid function [19]. Given the high prevalence of thyroid dysfunction in the PCOS population [20], this presents an added risk.
  • A keto diet is typically short-term, whether by design or as a consequence of how hard it is to stay in ketosis. This feeds into the cycle of yo-yo dieting which is both emotionally and metabolically unhealthy. If like traditional restriction diets, a ketogenic diet results in weight gain over the long term, then it can make your PCOS problems worse.

9. Con: There Are Better Diets For PCOS

The best opposing argument against a ketogenic diet for PCOS is that there’s a much better alternative.

A PCOS diet offers the same freedom from caloric restriction, while also achieving better outcomes.

Unlike the ketogenic diet, which only targets insulin, a PCOS diet also reduces inflammation. This is achieved by avoiding problematic foods and replacing them with better alternatives.

A PCOS diet is low carb, but not very low carb like the ketogenic diet. See my article on macros for PCOS here. I recommend women get around 20-30% of their energy from low GI carbohydrate foods. This allows for much greater dietary flexibility while still addressing insulin resistance. This way, many more important and fun foods can be included in a PCOS diet. Occasional deviations also have little-to-no significant impact on progress.

Unlike a ketogenic diet, a PCOS diet is a long-term lifestyle intervention. Because it doesn’t “feel like a diet”, this treatment safely and effectively manages PCOS symptoms. A PCOS diet promotes a healthy relationship with food (rather than focusing on weight loss). This makes it much more suitable for previous “failed” dieters and those at risk of disordered eating.

The testimonies from my free 30-Day PCOS Diet Challenge show the superiority of this dietary approach.

The Bottom Line

The ketogenic diet may offer some short-term benefits for women with PCOS. This is especially the case for overweight women concerned about type 2 diabetes. But while this intervention may be helpful, a PCOS-focused diet can get even better results.

A PCOS diet is more sustainable and less risky, making it better suited as a long-term lifestyle intervention. Start your journey to better health and fertility by signing up for my next free 30-Day PCOS Diet Challenge. You don’t need to wait for the next Challenge to begin though. Switch to a PCOS diet today with this free 3-Day Meal Plan.

Ready To Try A PCOS Diet?

  • Join my next free 30-Day PCOS Diet Challenge here. This is a live program where you’ll receive weekly meal plans and helpful video lessons. You’ll also be part of a motivated and inspiring community of like-minded women.
  • Download my free 3-Day PCOS Diet Meal Plan here. This is perfect for getting started before the next 30-Day Challenge begins.
  • Join my PCOS Monthly Meal Planning Service. This service includes hundreds of PCOS recipes within a pre-populated, yet customizable meal plan. It’s designed to save you time and help you apply a PCOS diet.
  • Sign up for my next Beat PCOS 10-Week Program. This is a comprehensive live program that runs quarterly. Topics covered include diet, PCOS-centric emotional eating, exercise, stress management, and more. The 10-Week Program includes the same recipes and meal plan as my monthly meal planning service.
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