• New research found that women with polycystic ovarian syndrome (PCOS) may experience weight loss and fertility benefits from a ketogenic diet.
• These effects may largely be tied to the keto diet’s ability to stabilize blood sugar levels, a key issue for most PCOS patients.
• Experts recommend women with PCOS speak to a healthcare professional before making any drastic dietary changes.

Women with polycystic ovarian syndrome may experience weight loss and increased rates of fertility by following a ketogenic diet, but not all experts recommend going to such extremes.

The keto diet has grown in popularity for its general weight loss benefits. The low-carb lifestyle has also been tied to benefits for people with diabetes and other endocrine disorders. Most recently, experts have looked at keto in relation to polycystic ovarian syndrome (PCOS).

A new study, published this month in the Journal of the Endocrine Society, found that going on a high-fat, low-carb diet may benefit women with PCOS regarding weight management and fertility.

PCOS is the most common hormone disorder in women, affecting 8–13% of reproductive-aged women.

The study found that women who followed a keto diet for at least 45 days not only had significant weight loss but also experienced improved reproductive hormone levels. On average, their ratio of follicle-stimulating hormone (FSH) was lower, increasing their chances of ovulating—and, therefore, of conceiving.

These effects may be partly due to a ketogenic diet’s ability to stabilize blood sugar, a major player in the diagnosis of PCOS.

“Low-carb diets [for PCOS] don’t have to be as extreme as keto, but any form of carbohydrate reduction…will lower insulin levels, if that nutritional approach can be adhered to long-term,” Rekha Kumar, MD, Chief Medical Officer at medically-assisted weight loss program Found and practicing endocrinologist in New York City told Health.

“When insulin levels are lowered, the ovary will function more normally and menstruation and ovulation can be restored,” she said. “It is not always so straightforward, but it can happen.”

How Might a Keto Diet Affect PCOS?

While online wellness accounts may claim that keto can “cure” PCOS symptoms like acne and night sweats, the new research focused on the diet’s effects on weight changes and specific hormone levels.

The researchers pooled data from numerous previous studies on women with PCOS, showing that adhering to a keto diet for at least 45 days yielded significant weight loss. In all studies analyzed, women lost weight by following a very low-carb keto diet.

Hormone levels also improved after women stuck to the diet for this period of time. Women on keto experienced a reduced ratio of luteinizing hormone to follicle-stimulating hormone (LH:FSH)—a key measure in diagnosing PCOS. Meanwhile, their testosterone levels sank and their serum sex hormone-binding globulin (SHBG) rose.

Losing weight is one of the top strategies for reversing insulin resistance, according to the Centers for Disease Control and Prevention (CDC). Considering that insulin resistance has been found in 95% of women who don’t ovulate, this finding could have a meaningful impact on fertility.

“One theory of PCOS is that the environment of high insulin impairs ovulation and reproductive function,” Kumar said. “By going keto or low-carb, the body is less insulin resistant or more insulin sensitive.”

Reduced testosterone could also help improve symptoms of PCOS, since, per the study’s authors, testosterone promotes hyperandrogenism. This condition drives symptoms like acne, unwanted hair growth, and absent menstruation.

But, the definition of a keto diet can vary significantly—so it's important to note how exactly what the diet is (or is not) that may contribute to reduced PCOS symptoms.

Rather than set parameters around exact grams of carbohydrates or fats, the researchers included studies that used the keywords “ketogenic diet” or “very low-carbohydrate diet.” For this reason, it’s difficult to say exactly how low-carb subjects’ meal plans were.

Sticking to the Keto Diet May Be Harder for PCOS Patients

Adherence to the keto diet involves upturning the typical Western diet of mostly carbs into a diet of mostly fats.

Kumar noted that sticking to keto is notoriously difficult for people with PCOS. That isn’t to say that people without PCOS are better at following the keto diet—in general, long-term adherence to the keto diet is poor.

But people with PCOS may have an even more difficult time following the eating plan because insulin resistance and high insulin levels make a low-carb or keto diet “practically against one’s biology or hormonal milieu,” Kumar explained.

If anything, women with PCOS tend to crave carbohydrates, she said.

That said, the new study did provide promising results of keto helping boost the health of women with PCOS. But considering the controversy around the diet, it’s important to check with a healthcare provider regarding your unique situation before switching up your meal plan.

“I do not think that the keto diet has enough benefits for PCOS symptom management to be recommended as a dietary strategy,” fertility and prenatal dietitian McKenzie Caldwell, MPH, RD, LDN told Health.

“While keto may help some folks manage their blood glucose levels in the short term, which may improve some symptoms, its long-term benefits have yet to be proven," she said.

Caldwell encourages assessing the big picture of your health before diving in.

“If you would like to try it, consider your personal history with disordered eating and whether cutting out or counting carbs is best for your mental health,” she said. “It is also important to weigh in your personal and family history of heart disease, as low carbohydrate diets can increase your cholesterol levels.”

Safely Following the Keto Diet for PCOS

If you do decide to try a keto diet to improve PCOS symptoms, it’s key to do so in a safe, balanced manner.

Creating a healthy high-fat eating plan isn’t a daily parade of butter and bacon. Instead, seek out fat sources that provide additional health benefits, such as fatty fish, olive oil, avocado, and nuts.

And, even on a low-carb diet, it’s critical to prioritize sources of fiber-rich carbohydrates.

“Many foods that contain carbohydrates, such as legumes, fruits, grains, and starchy vegetables, contain soluble fiber, which is important for long-term digestive and heart health,” Caldwell said. “These foods are also very important sources of vitamins, minerals, and antioxidants that are important not only for the reproductive years but for long-term health and well-being as well.”

Ultimately, the best diet for someone with PCOS may be a middle ground between full keto and a more mainstream, Western diet.

“Instead of a low carbohydrate diet, I like to take a ‘medium’ approach with my PCOS clients,” Caldwell said. “Instead of cutting out carbohydrates, we work on adding sources of fiber, protein, and fat alongside carbohydrates for optimum nutrition, blood sugar balance, and hormone health.”