Article authored by Readout Health with editorial oversight from Chief Medical Officer, Naomi Parrella, M.D.
Polycystic ovary syndrome (PCOS) is a metabolic and hormonal condition that affects between 8% to 13% of women of childbearing age around the world, and is considered the leading cause of infertility. There’s no cure for PCOS, but making lifestyle changes has been shown to considerably improve PCOS symptoms for a greater quality of life.
What are the common telltale signs of PCOS?
Women with PCOS may experience:
Irregular menstrual cycle, including fewer periods, more frequent periods, or cessation of periods
Hair on the face or chin
Acne on the face, upper back, or chest
Hair loss or thinning hair, baldness
Weight gain or difficulty losing weight
Skin darkening along the neck creases, underneath breasts, or around the groin
Having PCOS elevates the risk for other health disorders like high blood pressure and high cholesterol, sleep apnea, depression, and anxiety. Also, more than 50% of women with PCOS will develop prediabetes or type 2 diabetes by the time they reach the age of 40.
What causes PCOS?
Experts are still trying to figure out exactly what causes PCOS, but they believe that a number of genetic, environmental, hormonal, and metabolic factors are in play. Women with PCOS have more androgens, or male hormones, which can show up as acne, extra hair growth, and the prevention of ovulation during a menstrual cycle. Also, around 75% of women with PCOS experience obesity. Obesity around the midsection, called visceral obesity, is especially dangerous because this type of fat can change the general hormonal function of fat tissue. This leads to low-grade inflammation, which is shown to cause dysfunction in the ovaries as well as insulin resistance.
The close link between PCOS and insulin resistance
Insulin resistance is a term used to describe a state in which the body is not responding appropriately to insulin. This often leads to chronically high insulin levels, even when fasting or limiting carbohydrates in the diet. This is in comparison to normal insulin sensitivity, where the insulin is more responsive to eating behaviors and is low when fasting or after limiting carbs in the diet.
Insulin resistance is seen in 75% of women with PCOS, especially those who are older than 40, overweight, have high blood pressure and high cholesterol, and lead a sedentary lifestyle. It is believed that insulin resistance is not only a symptom of PCOS – too many androgens in the body can impair insulin action in muscle and fat tissue – but it is also a major contributor to it, as high insulin can cause ovaries to secrete excess testosterone which can impair ovulation and cause infertility, acne, and hair to grow on the face and chin.
One theory suggests that aside from having obesity, women with PCOS may also be more prone to insulin resistance due to an imbalance in gut health. The gut microbiota is made up of the different species of bacterial microorganisms that live in the digestive tract. Each type of bacteria serves a crucial role in maintaining health throughout life by regulating the immune system, digestion, and central nervous system. Having too many unhealthy microorganisms that throws off the balance between healthy and unhealthy bacteria can negatively affect health, including causing weight gain and insulin resistance.
Can a low carb diet help with symptoms of PCOS?
While no cure for PCOS exists yet, many women with PCOS find relief with lifestyle modifications like exercise and a healthy low carb diet. The severity of insulin resistance appears to be associated with the severity of a person’s obesity and PCOS symptoms, so for this reason, weight loss is recommended as an effective treatment for PCOS. Losing weight can lower both blood sugar levels and the resistance to insulin, and can also help to balance hormone levels. Even a 10% drop in weight may result in more regular periods and a higher chance of getting pregnant. This is important to know if you are thinking about starting a family, or you are not.
A low carb diet has long been linked with weight loss, and it appears that for women with PCOS and obesity, restricting carbs may significantly improve associated symptoms. For example, one 2021 study evaluated the effects of a low carb diet among 17 women with obesity and PCOS over 45 days. A daily maximum carb intake of 30 g resulted in an average drop in weight by 20.7 lb, a average reduction in waist circumference by 9.4 cm, an improvement in blood glucose by 10.07 mg/dL, and a drop in blood insulin concentration by 12.90 μU/mL.
Another study followed 18 women with obesity and PCOS and found that when they limited their carbs to under 50 g a day over 12 weeks, they saw a 26 lb drop in weight and a drop in blood glucose from 5.92 mmol/L to 5.22 mmol/L during week 4 and down to 5.11 mmol/L by the end of the 12 weeks. What’s more, the women’s menstrual cycle improved. By week 4, the women saw their menstrual cycle reduce from 72 days to 46 days, and down to 32 days by the last week.
Following a low carb diet may even help improve fertility, as well. Research from 2018 found that four women with PCOS who previously experienced irregular periods got on a regular menstrual schedule only 4 to 8 weeks after starting a new low carb diet, and two women were even able to conceive naturally.
Here’s why a low carb diet may help
Given such an impressive track record, it’s helpful to understand the science behind exactly how restricting carbs in the diet can lead to an improvement in PCOS symptoms. Unless you have type 1 diabetes, eating carbohydrates increases insulin in the body. Remember, PCOS is associated with insulin resistance, which means the body doesn’t respond appropriately to insulin. If the body doesn’t respond to insulin, carbohydrates will lead to elevated blood sugars, and eventually, prediabetes or diabetes. By limiting carbohydrates in the diet, there is no stimulus for more insulin. This allows the level of insulin in the blood to begin to decrease. In addition, when carbs are limited in your diet, the liver and muscles burn through the stored glucose for fuel. When that fuel supply of stored glucose is depleted, the liver begins to burn fatty acids to produce ketone bodies for fuel. So this means that when carbs are restricted in the diet, the body burns fat for its energy needs instead of glucose, or sugar. Making the switch from burning sugar for fuel to burning fat is associated with a boatload of health benefits, especially for women with PCOS, including weight loss, lower insulin and blood glucose levels, and a reduction in androgen secretion which may also result in improved fertility.