Is The Keto Diet BENEFiciaL for PCOS?


It’ s about time I shared my thoughts on the keto diet for PCOS. This is something that I get asked by my PCOS clients all. the. time. So I’m guessing that some of you might be interested in this topic as well!

The keto diet has gained a lot of popularity in recent years as a means for rapid weight loss.

There is SO much misinformation out there regarding diet and PCOS but the keto diet for managing PCOS might be least favorite of all.

Ahhh where to even begin! First let’s talk about what the keto diet actually is.

What is the keto diet?

The ketogenic diet or “keto” diet was developed in the 1920s as a therapeutic treatment for patient’s with epilepsy. A keto diet is very high in fat (about 75% of total calories), moderate in protein (about 20% of total calories) and low in carbohydrates (about 5% of total calories).

On a 2000 calorie diet, this would mean limiting carbohydrates to about 20-25 grams daily – less than 1 banana or 1 sweet potato.

By starving your brain of glucose (the body’s preferred source of energy coming from carbohydrates) your body is forced to burn fat for fuel in the form of ketones. A keto diet is NOT to be confused with a “low carb diet”.  

The keto diet also limits protein since protein can be converted to glucose through a process called gluconeogenesis.

Research has shown that a keto diet can improve epilepsy, lower blood sugar and insulin levels, improve insulin resistance and help with weight loss.

Burning fat for fuel? Lower blood sugar and insulin? Sounds great for PCOS! Not so fast…

The Keto diet Could Make PCOS symptoms worse

The glands that regulate the hormones in your body are very sensitive. When carbohydrate intake goes too low, this is a form of physiological stress on your body. As a result, your adrenal glands may start producing more cortisol (one of your body’s stress hormones).

Many women with PCOS already have overactive adrenals and higher levels of stress hormones in their body to begin with, so this can be a recipe for disaster.

Cortisol causes blood sugar levels to increase and can actually make insulin resistance worse over time.

Elevated levels of cortisol lead to more visceral fat (a fancy term for belly fat).

Research has shown that holding excess fat in your abdominal area increases a person’s risk for health conditions including type 2 diabetes and heart disease more than holding fat in other areas of the body.

Although initial weight loss may occur on a keto diet (as would cutting out any entire food group) the long-term impact of elevated cortisol levels from overly restricting carbohydrate intake may actually do more harm than good. 

The keto diet may negatively impact the gut microbiome

We know that the gut microbiome plays a major role in health and disease. Bacteria in the gut are crucial for the digestion and absorption of nutrients from food, immune function, the regulation of inflammation, the production of important vitamins, hormonal balance, insulin sensitivity and mental health. Shall I go on…?

There is a lot we still don’t know about the gut microbiome, but research has consistently shown that low bacterial diversity in the gut is harmful and a species-rich gut microbe community is beneficial.

One of THE most important ways to support the growth of beneficial bacteria in the gut is to consume a whole foods, fiber rich diet.  

What is the keto diet often deficient in? FIBER. Think vegetables, fruit, legumes, whole grains, etc.

Not to mention that fiber is crucial for promoting regular bowel movements. Going to the bathroom daily is essential for eliminating excess hormones.

The keto diet may be harmful for hormones

 Research has shown that overly restricting carbohydrates may result in irregular menstrual cycles or the complete loss of a period all together in some individuals.

Overly restricting carb intake may negatively impact thyroid hormones resulting in weight gain, mood disturbances, poor concentration and low energy levels. Sound fun?

The keto diet may increase your risk for being overweight in the future

The keto diet might produce rapid weight loss in the short-term, but it also might actually increase your risk for weight gain in the future.

Compliance and adherence to the keto diet in research studies is low, likely because of it’s restrictive nature. This means that it is probably not realistic for most people to follow in the long-term.

What is one of the biggest risk factors for weight gain? Chronic dieting (ahem...keto) & weight cycling.

When your body goes through periods of restriction a number of metabolic changes occur including greater fat storage, lean muscle loss and decreased energy expenditure. These are protective mechanisms that your body employs as a result of restriction.

The keto diet lacks important micronutrients

One of the major issues with PCOS is the underlying, low grade inflammation (evidenced by elevated inflammatory markers in women with PCOS). Women with PCOS are also at an increased risk for a number of micronutrient deficiencies.

If you’re following a ketogenic diet, you are likely missing out on crucial vitamins, minerals and antioxidants that have an anti-inflammatory and protective effect on your body (like colorful fruits and veggies!)

Higher fruit and vegetable intake is associated with lower levels of inflammatory markers and a decreased risk for developing chronic disease.

The keto diet can squash your social life

The keto diet can be incredibly stressful and socially isolating due to it’s restrictive nature. It takes a lot effort to count and micromanage every piece of food that goes into your body. Not to mention all of the fun foods you have to miss out on! I feel exhausted just thinking about it.

I’m going to go out on a limb here and say that most of us with busy lives don’t really want to live this way and be constantly stressing about food — we’ve got enough life stress as it is!

Final Thoughts

The keto diet may be necessary as a therapeutic intervention in SOME clinical cases when appropriate. This should be implemented with the guidance of your doctor and dietitian to ensure safety.

If you are pursing the keto diet to lose weight, improve energy, manage PCOS or balance hormones….you may actually end up worse off than when you started. I promise you — there is a better way!

I want to reiterate again that a keto diet is NOT just a low carb or controlled carb diet.

There are SO many ways to improve insulin resistance and manage PCOS that don’t involve the keto diet (read more here and here and here).

I work closely with clients to support them in determining their personal carb tolerance and a pattern of eating that is supportive of stable blood sugar and energy levels. Every individual is unique!

If you are serious about making dietary changes to improve your health and manage PCOS in the long-term…stop looking to generic diets and quick fixes.

Set up a free 30 minute discovery call if you’re interested in getting to the root of your symptoms and working with an integrative registered dietitian on a personalized nutrition and lifestyle plan for long-term health outcomes.

In the meantime you can check out some of my basic diet and lifestyle tips for PCOS here to get you started.

In health,

Jillian Greaves, MPH, RD, LDN

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