PCOS (polycystic ovary syndrome) is a common disorder among reproductive-aged women. Emerging research suggests that a ketogenic or low-carb diet may improve hormonal regulation, weight control and other PCOS-related issues. This article takes a detailed look at PCOS and how carbohydrate restriction combined with other lifestyle changes may be helpful for women struggling with this condition.
What Is PCOS?
PCOS was originally named Stein-Leventhal syndrome for the researchers who first described it nearly 100 years ago. It's a common endocrine disorder that typically begins in adolescence or early adulthood and is one of the leading causes of infertility. Up to 20% of women of childbearing age are estimated to have PCOS, including as many as 70% that are undiagnosed ( 1).
In PCOS, a woman's ovarian follicles fail to release an egg every 28 days as a result of hormonal imbalance: too much luteinizing hormone (LH) and not enough follicle-stimulating hormone (FSH). Therefore, instead of the egg maturing, it remains in the ovary and forms a small cyst. This process is repeated on a monthly basis, alternating between the two ovaries, leading to the formation of dozens of cysts over time.
High levels of LH stimulate the production of excess androgens (male hormones, including testosterone), which suppress ovulation. In addition, women with PCOS have low levels of sex hormone binding globulin (SHBG), which normally binds to testosterone in the blood. When SHBG is low, free testosterone rises. Besides interfering with ovulation, high levels of free testosterone can cause symptoms of masculinization. Finally, low levels of SHBG promote insulin resistance, and vice versa.
What Are the Symptoms of PCOS?
Some of the common signs and symptoms of PCOS include:
- Menstrual irregularities, including absent periods (amenorrhea) or infrequent periods (oligomenorrhea)
- Overweight and obesity
- Acanthosis nigricans (skin tags and darkened pigment in the skin folds of the armpits, groin, thighs and neck)
- Masculinization due to hyperandrogenism (high levels of testosterone, DHEA and other androgens). Symptoms include hirsuitism (excessive facial and body hair), acne, male-pattern baldness, and a deep voice
However, not every woman with PCOS experiences all of these symptoms. In addition, some don't even have the characteristic cysts on their ovaries.
Based on what is known as the Rotterdam consensus, women must meet at least two of three criteria to be diagnosed with PCOS:
- Infrequent or absent menstrual periods
- Polycystic ovaries confirmed by ultrasound
There are four different phenotypes of the disorder, yet only one in which all three criteria are met:
- Frank or Classic PCOS: menstrual irregularities, hyperandrogenism, and polycystic ovaries
- Ovulatory PCOS: regular periods, hyperandrogenism, and polycystic ovaries
- Non-PCO PCOS: menstrual irregularities, hyperandrogenism, and normal ovaries
- Normoandrogenic PCOS: menstrual irregularities, normal androgen levels, and polycystic ovaries
In addition to infertility and other chronic symptoms, women with PCOS are at increased risk for a number of diseases and health conditions, including:
- Type 2 diabetes
- Coronary artery disease (CAD)
- Non-alcoholic fatty liver disease (NAFLD)
- Obstructive sleep apnea
Insulin Resistance and Hyperinsulinemia Often Play a Major Role in PCOS
Insulin resistance and hyperinsulinemia are extremely common in PCOS, affecting about 64% of all women with the disorder, mainly those who are overweight or obese (2).
In women with PCOS, high levels of free testosterone and low levels of SHBG promote insulin resistance and the storage of visceral fat in the belly and around the liver and pancreas. Excess visceral fat drives insulin resistance, inflammation, and further stimulates androgen production, creating a vicious cycle that can seem impossible to break ( 3).
However, it's important to remember that not every woman with PCOS experiences the classic symptoms of the condition.
On the other hand, many have metabolic syndrome, an insulin-resistant condition strongly linked to type 2 diabetes.
Metabolic syndrome is formally diagnosed by meeting at least 3 out of 5 criteria:
- Large waist circumference: 35 inches (89 cm) or higher for women
- Elevated triglycerides: 150 mg/dL (1.7 mmol/L) or higher
- Low HDL cholesterol: 50 mg/dL (1.3 mmol/L) or lower for women
- High blood pressure: 130/85 mm Hg or higher
- Elevated fasting blood sugar: 100 mg/dL (5.6 mmol/L) or higher
One study in women with PCOS found that 43% met the diagnostic criteria for metabolic syndrome. Compared to those with PCOS alone, women with both conditions were found to have significantly higher levels of free testosterone, lower levels of sex-hormone binding globulin (SHBG) and more acanthosis nigricans – all symptoms of severe insulin resistance ( 4).
PCOS and Weight Loss
Insulin-resistant PCOS sufferers also tend to have an extremely difficult time achieving and maintaining a healthy weight. In the US, about 80% of women with PCOS are overweight or obese ( 5).
Because obesity perpetuates insulin resistance and hormone imbalances, these women are frequently urged to lose weight in order to reduce disease risk and improve hormonal regulation. However, as anyone who has struggled with this disorder knows, losing weight and maintaining the loss is often easier said than done.
In studies, severe calorie restriction has been shown to produce weight loss in most people, including those with PCOS. In a 4-week controlled study, when women with PCOS consumed a 1000-calorie diet with either higher or lower protein content, both groups lost weight and had decreases in blood sugar and insulin levels ( 6).
Although this shows that very-low-calorie diets can lead to weight loss, they aren't sustainable or healthy long term. Cutting calories too low can lead to rebound hunger and overeating, low energy levels and mood issues. Additionally, severe calorie restriction causes loss of lean muscle and a reduction in metabolic rate, making weight loss and maintenance even more difficult in the future.
Low Carb and Ketogenic Diets for PCOS
By contrast, low-carb and ketogenic diets may be ideal for women with PCOS, especially those with insulin resistance.
First off, carb restriction has been linked to loss of weight and visceral fat, reductions in insulin and blood sugar levels, and improvements in other cardiac disease risk factors in those with metabolic syndrome.
In one study, people with metabolic syndrome who consumed approximately 1500 calories on a low-carb diet lost 14% of their body fat and experienced a 50% or greater reduction in insulin levels, insulin resistance and triglycerides ( 7).
Anecdotal evidence about carb restriction's effects on PCOS is pretty impressive.
Several women with PCOS have reported major weight loss, resumption of normal menstrual cycles and fertility, and other beneficial health changes as a result of switching to a low-carb or ketogenic lifestyle.
And although there are very few formal studies exploring carbohydrate restriction for PCOS, those that exist are encouraging.
In a small study lasting 6 months, 11 women with PCOS lost an average of 11% of their body weight while following a ketogenic diet restricted to 20 grams of carb daily. In addition, their fasting insulin levels dropped by 54%, and their LH:FSH ratio improved. Moreover, two of the women who had been struggling with infertility became pregnant during the course of the study ( 8).
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Although ketogenic diets show a lot of promise for PCOS, more liberal low-carb intake may also be effective for weight loss and improving symptoms.
For instance, in a 2015 study, 24 women followed a low-starch, low-dairy diet containing about 70 grams of net carb per day. After 8 weeks, they experienced dramatic reductions in insulin levels, free testosterone levels, insulin resistance, and triglycerides, along with an average weight loss of 19 pounds (8.6 kg). It's worth mentioning that one woman became pregnant during the study, although researchers did not attribute this to the diet ( 9).
Consuming a low-carb diet may also help improve mood and quality of life in those with PCOS. In a controlled study, women with PCOS followed either a low-carb, high-protein diet or a low-protein, high-carb diet for 16 weeks. Although weight loss was similar in both groups, the low-carb diet was linked to a significant decrease in depression and improvement in self-esteem, whereas no such changes occurred in the high-carb group ( 10).
In addition to reducing insulin levels, ketogenic and low-carb diets also help control appetite, resulting in a spontaneous reduction in calorie intake that can lead to weight loss without hunger.
Despite the limited formal research on low-carb and ketogenic diets in women with PCOS, it stands to reason that any way of eating that decreases insulin resistance and hyperinsulinemia may be effective for managing the disorder.
Keto-friendly foods that may be especially beneficial for women with PCOS
Foods high in lignans, such as flaxseed
Lignans are a type of fiber known to increase SHBG and reduce androgen and insulin levels. A PCOS case study found that consuming about 1 ounce (30 grams) of flaxseed per day dramatically lowered free testosterone levels (11). Additionally, a randomized controlled trial in obese older women showed increased insulin sensitivity and lower insulin levels in the group that took flaxseed compared with those who received a probiotic or placebo ( 11, 12).
Other low-carb foods rich in lignans include sesame seeds, berries, pumpkin, broccoli and curly kale.
Fatty fish like sardines, salmon, herring and mackerel: The omega-3 fats found in fish oil may help reduce insulin levels and improve insulin sensitivity in those with PCOS ( 13, 14).
Both walnuts and almonds have been shown to reduce androgen levels and improve heart disease risk factors in women with PCOS ( 15). Other nuts haven't been studied for their effects on PCOS, but it's likely that they provide similar benefits.
Other Lifestyle Modifications for PCOS
In addition to a following a ketogenic or low-carb diet, here are some additional strategies that may be beneficial for PCOS management.
- Resistance training: In a 4-week study, performing resistance training 3 times a week led to lower androgen and SHBG levels, loss of weight and increased muscle mass in women with PCOS ( 16).
- Aerobic exercise: Aerobic exercise has been shown to help lower inflammation, reduce insulin resistance, promote weight loss and improve reproductive function in those with PCOS. In one study, 56% of women with amenorrhea who performed aerobic exercise for 12 weeks began menstruating again ( 17, 18).
- Yoga: Based on research in adolescents with PCOS, practicing yoga seems to improve reproductive hormone levels, insulin resistance and cardiovascular disease risk factors, whether or not weight loss occurs ( 19, 20).
Because all types of exercise can provide benefits if done on a regular basis, it's best to choose forms of physical activity that you can enjoy and can stick with long term.
Found in herbs like goldenseal, barberry and Oregon grape root, the compound known as berberine has been used in Chinese medicine for centuries to treat a variety of health conditions. In one study of women with PCOS, berberine was found to reduce insulin resistance as effectively as metformin, an insulin-sensitizing medication frequently prescribed for PCOS. What's more, berberine led to slightly more weight and belly fat loss, greater increase in SHBG, and lower levels of free testosterone than an equivalent dosage of metformin ( 21).
Recommended dosage: 500 mg taken 2-3 times per day.
Some studies suggest that this spice may improve insulin resistance and help restore ovarian function in women with PCOS ( 22, 23).
Recommended dosage: 1/2 to 1 teaspoon per day.
Apple cider vinegar
Apple cider vinegar has been shown to increase insulin sensitivity in several studies, including a small but impressive trial in women with PCOS. When 7 women with PCOS took 15 grams (1 Tablespoon) of apple cider vinegar, 4 resumed ovulating within 40 days, 6 experienced a measurable reduction in insulin resistance, and 5 had a decrease in their LH/FSH ratio ( 24).
Recommended dosage: 1-2 Tablespoons (15-30 ml) per day. It's best to start with 1 teaspoon and work up to the recommended dosage gradually in order to avoid nausea and other digestive symptoms.
This compound occurs naturally in many plants and can also be produced commercially. It comes in two forms: myo-inositol and d-chiral inositol, both of which have been shown to significantly reduce insulin levels and improve hormonal balance in PCOS ( 25, 26, 27).
Recommended dosage: 1200 mg of d-chiral inositol or 2000 mg of myo-inositol once per day.
Always speak with your doctor or healthcare provider prior to taking any supplements other than a multivitamin.
Acupuncture is a traditional Chinese medicine practice that involves inserting very thin needles into the skin to relieve pain and correct imbalances in the body. It's been credited with beneficial effects for all kinds of health disorders, including PCOS.
Indeed, several randomized controlled trials have found that acupuncture can help restore insulin sensitivity and improve hormone levels ( 28, 29, 30).
In one study, 86 overweight and obese women with PCOS received either metformin or acupuncture treatment for 6 months. By the end of the study, fasting insulin, insulin resistance, LH: FSH ratio, and cardiovascular disease markers were significantly reduced in both groups. However, the acupuncture group experienced greater weight loss, reduction in waist circumference and improvement in menstrual function than the metformin group ( 30).
PCOS is a disorder that can seem frustratingly difficult to manage. Most women with PCOS deal with multiple health challenges, including insulin resistance, infertility, obesity and increased risk for heart disease.
Although losing weight can improve many PCOS symptoms, drastic calorie restriction isn't a good option for getting rid of excess body fat. It's only a temporary measure that can't be sustained long term and often leads to rebound hunger and weight gain.
In contrast, carbohydrate restriction seems to be the best dietary approach for women with PCOS. It's been shown to reduce insulin resistance and other risk factors for diabetes and heart disease. Moreover, ketogenic and low-carb diets promote loss of weight and body fat by controlling appetite, lowering insulin levels and improving hormonal regulation. Finally, a low-carb lifestyle can be nutritious, well-balanced and easily maintained long term.
Although there's no denying that study results and many anecdotal reports support ketogenic and low-carb diets for PCOS, it must be pointed out that they may not be effective in every case. Each woman is different and must find what works best for her.
However, if you have PCOS, consider trying a low-carb or ketogenic diet, along with some of the supportive lifestyle measures discussed in this article. Taking these steps may help improve your fertility, weight, overall health and quality of life.
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