Physicians treating PCOS encourage weight loss for a variety of reasons including its effectiveness at reducing inflammation and managing insulin. That said, a laser focus on weight without proper attention to nutrition and health can be detrimental to these very goals. What’s more, the stress of a weight-centric approach can take a significant toll not just on general health but on mental and emotional wellbeing as well. To this end, if you struggle with weight loss or feel that there is an insurmountable barrier to reaching a target weight goal, do not despair; there are other paths to health and wellbeing with PCOS that are not based on what the scale may have to say but rather how other biomarkers such as blood sugar, insulin, and lipid levels are responding to your interventions. This approach takes the focus away from weight and puts it on implementing changes that are going to help you to feel better in your body, whatever size it may be. These include positive changes like getting better sleep and reducing sleep apnea, managing stress, and focusing on the quality of your diet without the additional burden of weight loss goals.

For many women with PCOS who are overweight, losing weight can improve general health, reduce depression, improve fertility, and more. The data on how to go about adjusting diet is complex, and at times contradictory. In the 2023 International Evidence Based Guidelines for the Assessment and Management of PCOS, the committee suggests a number of balanced-diet approaches are productive (with no one approach being superior) and that healthy eating principles applied to the general population also apply to the PCOS population. For those with excess weight, a 30% energy deficit (approximated by a caloric reduction of 500–750 calories per day) is recommended by some experts. However, some believe these levels are unduly restrictive. To maximize chances of success, the guidelines suggest incorporating personal dietary preferences and avoiding “unduly restrictive and nutritionally unbalanced diets.”

Importantly, some women with PCOS are normal-weight and can have a genetic susceptibility for PCOS. They also can develop preferential intra-abdominal fat accumulation, often detected clinically by an increase in the waist to hip ratio. This is important because the amount of fat stored around the waist as a measure of fat within the abdominal cavity is a risk factor for subfertility and metabolic diseases that are further worsened with increased BMI. In a long-term prospective study of PCOS women followed for at least 10 years (mean follow-up 16.9 years) from youth to middle age, a 39.3% prevalence of diabetes was linked with an increased BMI at the end of the study (Gambinieri 2012). For this reason, preventive healthcare strategies, often beginning in adolescence, play an important role in maintaining the long-term health of these women through proper body weight maintenance.

Why Lose Weight If You Have a High BMI

BMI & Caveats

Body Mass Index (BMI) is a tool used to approximate body fat composition using a person’s weight in relation to their height. Typically, but not always, BMIs of 18.5–25 are considered “normal” while BMIs 26–30 are regarded in purely clinical terms as “overweight” and those 30-and-over are regarded in clinical terms as “obese.”

BMI indicators can vary by race, heritage, and other factors. For example, a BMI threshold of 30 kg/m2 that may indicate an increased risk of a disease for a person of Caucasian ethnicity is not applicable to someone of South Asian origin who will likely experience an increased risk of the same disease at a significantly lower BMI.

It’s critical that you talk with your doctor about how your BMI should inform dietary, exercise, and treatment decisions.

General Health Benefits

For a person with a high BMI, even modest amounts of weight loss can improve general health. People in the high BMI range are at elevated risk of developing diabetes, but a weight loss of 2.5% or more significantly reduces that likelihood. The data below shows how a variety of negative health conditions ranging from triglyceride levels to knee pain, depression, and sexual function, can be ameliorated by weight loss ranging from as little as 2.5% to over 15% of body weight.

Fertility

There is an inverse correlation between the fertility and BMI of women and their ability to conceive, as you can see below. We should also point out that having too low of a BMI can be problematic.

This is true for women who conceive without treatment (above) or with treatment. Below is one study, analyzing data from over 200,000 IVF cycles, that showcases how high BMI negatively correlates with live births, including in those with PCOS.

A major question is whether preconception diet and lifestyle improvements improves fertility success following ovulation induction. In one study below, amongst PCOS patients with a BMI of 27-or-greater, patients who attempted dietary and lifestyle modifications before starting treatment for ovulation induction recorded significantly higher rates of success. The “lifestyle” change group on average lost about 5% of their body weight before starting treatment. This “5% target” tends to be the one most studies cite in association with sufficient weight-loss to improve the odds of conception for PCOS patients.

Pregnancy

Hopeful parents want healthy pregnancies—so even if a person conceives without making adjustments, lowering elevated BMIs is still important. There is a close association between elevated BMI and negative (or dangerous) pregnancy outcomes. Below are data from the United Kingdom on over 250,000 singleton deliveries that shows the correlation between maternal BMI and risk of preeclampsia, emergency C-section, and postpartum hemorrhage.

Why Control Insulin

PCOS is associated with hyperinsulinemia or high levels of circulating insulin in the blood. This presents problems both to general health and to fertility and we’ll look at both. Later you’ll find a breakdown of the tests to measure hyperinsulinemia, their respective trade-offs and ranges doctors find reassuring and concerning.

About 70% of PCOS have insulin resistance. For those with a BMI above 30, the incidence of insulin resistance is estimated to be somewhere between 70%–80% while that number falls to around 20%–25% for those with a BMI below 25 (Marshall, 2012)—though some experts believe all normal-weight PCOS patients have some element of insulin resistance.

General Health

Chronically high insulin is detrimental to general health as it is closely associated with numerous medical issues. The most commonly known of these issues is type-II diabetes - a condition that itself further increases the risk of coronary artery disease (CAD). However, it is important to note that even among non-diabetic patients, insulin resistance is similarly problematic. For instance, below are data from the journal Nature (Cho, 2019) showing that insulin resistance is associated with the presence of CAD and obstructive CAD in non-diabetic patients. There are plenty of other studies that showcase similar correlations between high insulin levels and type 2 diabetes, CAD, and chronic inflammation among other metabolic diseases (Thomas 2019, Roberts, 2013). For these reasons, controlling insulin is a primary concern in dealing with the long-term health consequences of PCOS.

Fertility

Insulin stimulates the production of androgens in the ovaries. The overall effect is an increase in preantral follicle count and an arrest in dominant follicle selection (Guidelines, 2018). In short, insulin resistance can keep eggs from properly developing in the ovary.

One example of this can be found in a Chinese study that measured various parameters among normal-BMI patients with and without insulin resistance. The study noted that patients with insulin resistance had a lower percentage of mature eggs and produced fewer extra freezable embryos. The study recorded a discrepancy in IVF success rates (favoring non-insulin resistant patients) that trended towards, but did not meet, statistical significance.

Health of Your Child

Hyperinsulinemia increases the likelihood of developing type 2 diabetes, and with that comes a significant increase in risk of serious negative health outcomes in offspring. For this reason, some doctors believe it’s unwise for hopeful parents to try to conceive until their insulin resistance is under control. A Danish study that looked at health outcomes in almost two million singleton births over three decades showed that children exposed to diabetes (either type I or II) in utero were at increased risk of cancerous tumors, circulatory system diseases, and a range of birth defects. It is useful to note that although the relative increase in risk is significant, the absolute risk is still small, with the maximum absolute risk being about 1.1%. Still, given the severity of these conditions and their impact on affected families, dietary and lifestyle interventions aimed at reducing the risk are highly encouraged (data from Wu 2012).

A Note on Differing Tests of Insulin Resistance

There are two common ways that your body’s ability to handle glucose may be assessed: An oral glucose tolerance test (OGTT) and a hemoglobin A1C (HbA1c) test. Below we provide a description of both methods as well as a table of additional parameters clinicians look out for.

OGTT: Measures how your body responds to sugar. It involves measuring your blood glucose level after an eight-hour fast and then again two hours after a challenge dose of glucose ingested in the form of a drink. Some tests may require additional post-consumption blood draws at one- and three-hour intervals after ingestion of the glucose. For these reasons, the test can be painstaking for patients.

HbA1c: Measures average blood sugar over the course of the previous 3 months. This test requires one blood draw without fasting or any additional blood draws, making it the preferred test for patients and many doctors. That said, some healthcare professionals believe that the 75-gram oral glucose tolerance test is the most accurate method to assess glucose control in PCOS.

A Quick Note of Caution

Before we begin, it’s useful to highlight the importance of consulting a nutritionist, although unfortunately few OBGYNs or fertility clinics have one on staff. As a result, you may need to seek guidance beyond the four walls of your clinic.

Discussing the “optimal” diet for PCOS patients is difficult because PCOS patients differ in terms of what is happening to their bodies & what they hope to achieve (e.g. improving fertility, reducing acne).

For most (but not all) PCOS women who are overweight and trying to conceive, the objective is to decrease weight and increase exercise (helps to resume ovulation) thereby lowering insulin resistance (critical for the health of the parent and offspring).

General Health

When it comes to the role of nutrition in PCOS, no one diet has emerged as a panacea. Most diets showcasing good results feature a balance of proteins, fats, and carbohydrates—often relegating diets that focus on consuming one food group (e.g. the keto diet), or leave out another (e.g. Atkins) to perform no better than others. Importantly, “In women with PCOS, there is no or limited evidence that any specific energy equivalent diet type is better than another, or that there is any differential response to weight management intervention, compared to women without PCOS (Teede 2018). Therefore, tailoring dietary changes to an individual’s food preferences, based upon general population recommendations, allows a more flexible approach to reducing energy intake that aims to reduce the weight gain that commonly follows long-term management.

That said, a few trends have emerged from the literature. First, diets that are balanced and feature low-glycemic index foods (e.g. fruits, vegetables) and whole grains have proven to be productive. For instance, in one study of PCOS patients on a calorie-restricted diet, those who ate a greater percentage of whole grains, fruits, and vegetables and who avoided saturated fats recorded reduced BMIs and improved serum insulin (Asemi, 2014).

Diet and Ovulation

The Nurses Health Study

Many women with PCOS have inconsistent or nonexistent periods, making it difficult to conceive. A first step is to resume ovulation and one study looked closely at the association between a person’s diet and their cycles. There is no evidence-based PCOS-specific diet. The Nurses Health Study (NHS) II was a prospective trial following 100,000+ women in their reproductive years that closely tracked diet and health measures. While the NHS did not focus solely on women with PCOS, its size, rigor and duration of follow-up makes it a possibly useful source. That said, not all women with ovulatory issues have PCOS and not all PCOS patients experience ovulatory challenges.

Dairy

One question that tends to come up with patients who don’t ovulate regularly revolves around dairy intake. Generally speaking, experts suggest that patients consume whole-fat, rather than low-fat, dairy as NHS data shows women who consumed high fat dairy were less likely to run into ovulatory issues than women who consumed low fat dairy.

Meat versus Vegetable Protein

The Nurses Health Study also looked at trends as they pertain to protein. The investigators noticed a few trends. First, women who had protein comprising 20%-or-more of their daily calories were 40% more likely to encounter ovulatory issues.

By comparison, each incremental serving of vegetables (rather than protein) correlated with lower ovulation. Below you can see the divergent impact of meat and vegetables beyond a certain threshold.

Trans Fats

Trans fats are often found in commercial fried and baked goods and when Harvard investigators looked more closely at the Nurses Health Study data, they noticed women who received more than 2% of their energy per day from trans unsaturated fats were 73% more likely to encounter ovulatory issues. Investigators concluded “trans unsaturated fats may increase the risk of ovulatory infertility when consumed instead of carbohydrates or unsaturated fats commonly found in non hydrogenated vegetable oils.”

Data from small studies show promise of a few choice supplements in ameliorating some of the negative effects of PCOS, although there is a need for larger, randomized controlled clinical trials before any definitive answers can be gleaned.

Below are a handful of studies we find to be especially useful when weighing the value of taking supplements to conceive as a woman with PCOS. Additionally, we’ve constructed a table below characterizing some of the more common supplements and what underpinning they may have—if any at all—to address PCOS-related conditions.

Inositol

Inositol, a sugar alcohol available as an over the counter nutrition supplement, is arguably the cheapest and easiest intervention aimed at improving fertility for women with PCOS. Two forms of inositol are relevant in the PCOS arena: Myo-inositol and D-chiro-inositol.

Impact of Inositol

Myo-inositol works by promoting glucose uptake and has been shown to increase the activity of follicle stimulating hormone (FSH)—the hormone that promotes development of eggs in the ovary. D-chiro-inositol has been shown in some studies to ameliorate insulin-stimulated androgen synthesis in the ovary (Tambo et al., 2017). Women with PCOS who took inositol observed clinical outcomes that included improved ovulation and menstrual cycles with no major side effects reported, making this supplement an easy first step intervention (Pundir et al., 2018).

Possible Drawbacks

The combination of availability, low cost, and general tolerance provide a good rationale for trying inositol but with the caveats that there is currently no convincing clinical trial data demonstrating its effect on pregnancy or live birth rate (Ibid). Furthermore, at least one study cast some doubt as to whether D-chiro-inositol is either of use or detrimental as a stand-alone or in combination with myo-inositol (Garg and Tal, 2016). Thus, as with all experimental therapies, this underscores the need for more research. As with all supplements and over the counter interventions, we encourage you to discuss this with your healthcare team before adding it to your regimen or, if you are already taking it, to include that information on your intake forms.

Vitamin D

Vitamin D is a fat-soluble vitamin and its primary source is through exposure to sunlight. It is also available in limited amounts in some foods including fatty fish and egg yolks. Because maximal production requires penetration of the sun’s ultraviolet rays into the deepest layers of the epidermis, people with darker skin tones as well as those who have minimal exposure to the sun are at increased risk of vitamin D deficiencies. It is available as an over-the-counter oral supplement as well as an intramuscular injection.

Impact of Vitamin D

In a small trial involving high BMI adolescent patients, vitamin D supplementation improved insulin sensitivity (Belenchia, 2013). In women with PCOS who were deficient in vitamin D, supplementation was shown to be associated with a lowering of serum AMH levels, which are abnormally heightened in PCOS (Irani, 2014). Because AMH impairs follicular growth by inhibiting follicle selection, leading to inadequate estrogen rise, this outcome may bode well for ovulation. Still, a review of 38 studies investigating the effect of vitamin D on ovarian reserve could not establish a significant association between serum vitamin D levels and any markers of ovarian reserve. That said, researchers believe that some of the data point to a positive impact, calling for more research to distinguish the adverse effects of obesity from those of Vitamin D deficiency in reproduction (Karimi 2021).

Fertility

In one study of 750 women with PCOS undergoing ovulation induction for five cycles, women with more normal levels of Vitamin D achieved significantly higher ovulation rates, and in turn birth rates, than those who were “vitamin D deficient.”

Possible Drawbacks

Although rare, it is possible to take too much vitamin D, precipitating symptoms associated with vitamin D toxicity. The main symptoms are a result of abnormally high blood calcium levels that arise out of too much vitamin D and can be systemic, affecting primarily the nervous, gastrointestinal, and renal systems.

Berberine

Berberine is a naturally occurring alkaloid found in plants and is available over the counter as an oral supplement generally found in capsule and liquid forms. Berberine is not well-studied but has been claimed to be associated with a positive fertility effect.

Impact of Berberine

A small study on 37 people with metabolic syndrome showed that 300 mg of berberine administered three times daily over the course of 12 weeks was effective at reducing BMI as well as fasting plasma glucose and insulin levels (Yang 2012). Another small study in Chinese women with PCOS showed that 400 mg of berberine administered three times daily for four months improved ovulation rate (Li 2015). In a small trial, berberine appeared about as good as metformin in increasing insulin sensitivity and reducing the levels of androgens circulating in the blood (Wei 2012). In a randomized study across 19 clinics in China comparing berberine, letrozole, and berberine combined with letrozole for ovulation induction in PCOS women, the cumulative live birth rate was 22%, 36% and 34% respectively, showing lack of efficacy in using berberine either alone or in combination (Wu 2016).

Possible Drawbacks

Overall, berberine is well-tolerated. Rare reports of gastrointestinal side effects seem to be overcome by reducing the dose. That said, there are conflicting data on whether or not berberine alters the hyperandrogenemia issues of PCOS. It is hypothesized that increasing levels of sex hormone binding globulin (SHBG) can bind to circulating testosterone and reduce its availability in the ovaries. However, some studies have shown berberine to decrease SHBG and more data is needed.

Other Supplements

Below is a table that includes detail on a number of the more popularly-considered supplements as they pertain to patients with PCOS. While each may be supported by data indicating they have a role to play, few studies involving supplementation are rigorous nor address safety considerations regarding fetal exposure. As always, it’s important to have a careful conversation with your doctor about which supplements, if any, are appropriate given your circumstances.