Weight gain & PCOS: separating risks, myths, and facts
Most women (80%) with polycystic ovary syndrome (PCOS) have an above average or high body mass index (BMI),1 with weight gain found to be significantly associated with PCOS.2
Most women with PCOS also have insulin resistance,3 which is thought to contribute to weight gain. The body uses insulin to break down the glucose that enters the blood after we eat food, and when we are insulin resistant, it means that our cells are resistant to insulin and so are unable to use it to break down the glucose as effectively.4 This then prompts the body to produce more insulin in order to compensate.
Higher insulin levels in women with PCOS can also cause the ovaries to produce androgen hormones, such as testosterone, that can impact other PCOS symptoms, such as hirsutism (increased body hair), acne, and irregular periods.5
Androgen hormones are sometimes known as ‘male’ hormones because they play a role in the function and presentation of male traits and reproductive function. Some studies have also suggested that higher androgen levels may cause women with PCOS to gain weight around their abdomen6 — where men would be likely to gain weight.
Much research and clinical guidelines advocate weight loss as a first-line treatment for managing PCOS symptoms, and indeed, sometimes weight gain itself can actually increase the amount of insulin within the body, creating a vicious circle.
But the impacts of weight loss and managing PCOS symptoms are much more complex than simple advice to ‘slim down’: what does healthy weight loss look like, and what are the exact risks associated with weight gain and PCOS?
Myth: I can tell my weight is dangerous just by looking at my BMI
Your body mass index (BMI) is a number that is calculated by dividing your weight by your body height, squared, and is gauged on an incremental scale in relation to an ‘ideal’ weight range. It is widely accepted by medics and researchers as a useful tool in assessing someone’s physical health, but is not without flaws: for example, BMI does not take into account the presence of muscle, which weighs more than fat.
As studies have found that it is possible to be metabolically healthy and ‘obese’, it is important to investigate other measures beyond BMI that could indicate a more complete picture of your health and any risks you face
‘Obesity’ is a category defined by BMI, where a person’s BMI is within the range of 30-39.9. The NHS notes that a more useful way to measure weight is via waist circumference7, while other evidence suggests that waist-to-height ratio is a better discriminator for cardiovascular risk factors than BMI.8
While studies have shown that BMI is the strongest correlative factor of PCOS9 — that is, as BMI increased by increment, the risk of reporting PCOS increased — it is important not to narrow our reading of how PCOS impacts someone based solely on this number. BMI should not be taken as a sole measure of health, and instead considered as indicative among other factors.
As studies have found that it is possible to be metabolically healthy and ‘obese’10, and because different women may be impacted differently by PCOS and weight gain, it is important to investigate other measures beyond BMI that could indicate a more complete picture of your health and any risks you face. For example, it has been recommended that women with PCOS have blood tests that measure their cholesterol levels.11 Your doctor may also check your blood pressure or perform a glucose tolerance test.
Fact: Consider BMI in the context of other health measures
Myth: If I’m skinny, my PCOS symptoms will go away
While it has been shown that healthily losing a moderate amount of weight can work to alleviate PCOS symptoms in ‘obese’ women, lean women with PCOS have been found to still experience insulin resistance and excessive androgen production.12 Thin women with PCOS have higher levels of insulin in their blood than women without PCOS, which may cause metabolic abnormalities.13
There is disagreement among the medical community as to whether lean women with PCOS experience insulin resistance to the same degree as larger women, however, it has been shown that insulin resistance is present within both lean and larger women.14 This suggests that there may be other factors beyond insulin resistance that impact weight gain in women with PCOS.
The goal of any weight-loss plan as a treatment for PCOS should function as part of a broader treatment plan that is based on what ‘healthy’ looks like for you
Just as exercise may be suggested as part of a treatment plan for ‘obese’ women with PCOS, resistance exercise can be a useful way for lean women with PCOS to slow the production of androgens and improve reproductive function.15
While there is some research investigating the impacts of PCOS within lean women, there is still debate around how to best manage these symptoms.16
Fact: Lean women with PCOS also experience symptoms, and healthy changes to diet and exercise can be beneficial for all bodies
Myth: Losing weight can only be a good thing if I have PCOS
Lifestyle interventions and weight loss are generally accepted as first-line therapy for larger women with PCOS,17 with studies showing that moderate weight loss (more than 5% of a person’s body weight) via long-term calorie restriction can lower the concentration of insulin and improve menstrual function and fertility.18
Nutrition plays a key role here. Myo-inositol is a B-group vitamin that has been shown to reduce insulin resistance and contributes to improving reproductive function in women with PCOS.19 It is a type of inositol, which is a carbohydrate produced in the human body and also appears in plants, foods, and animals. Inositol plays an important role in transmitting messages within the body, and has been studied for its specific use in treating women with PCOS. It is thought that due to myo-inositol’s role in improving the body’s ability to break down glucose, it can aid weight loss.
Moderate weight loss should not be confused with an aim to ‘be skinny’ or necessarily with a ‘thin’ physical appearance. Instead, the goal of any weight-loss plan as a treatment for PCOS should function as part of a broader treatment plan that is based on what ‘healthy’ looks like for you.
You should always consult with your doctor to incorporate any lifestyle interventions and treatment plans, particularly where weight loss is suggested. Remember that this is not because you ‘aren’t good enough’ or have somehow ‘failed’ — you are simply making changes to manage a condition that is impacting your body in a particular way.
Fact: Healthy weight loss can help manage PCOS, but this shouldn’t be equated with the pressure to be ‘skinny’. A moderate amount of weight loss over a longer period of time has shown benefits in reducing severity of symptoms
What does a healthy weight with PCOS look like?
Every woman is different, and her body weight should be considered in relation to the complete context of her health and lifestyle. BMI is an indicative measure that is correlated with PCOS, but there are other measures of health that are important in understanding exactly how your body is impacted by PCOS. What ‘healthy’ looks like for you will depend on the outcomes of these investigations and how you are experiencing various PCOS symptoms.
However, healthy lifestyle interventions can benefit any type of body with PCOS, especially where it comes to nutrition and exercise.
Crucially, ‘skinny’ does not equal ‘healthy’ and should not be mistaken for lifestyle changes designed to impact moderate weight loss over longer periods of time. It is possible to lose moderate amounts of weight in a healthy way, and you should receive support from your GP in creating a plan that works for you and, ultimately, has the aim of making you feel good.
1. Goyal, M. & Dawood, A.S., Debates regarding lean patients with polycystic ovary syndrome: a narrative review, Journal of Human Reproductive Sciences, 2017, vol 10 (3) pp 154-161
2. Teede, H.J. et al, Longitudinal weight gain in women identified with polycystic ovary syndrome: results of an observational study in young women, Obesity, July 2013, vol 21 (8)
3. Goyal, M. & Dawood, A.S., Debates regarding lean patients with polycystic ovary syndrome: a narrative review, Journal of Human Reproductive Sciences, 2017, vol 10 (3) pp 154-161
4. Lebovitz, HE, Insulin resistance: definition and consequences, Experimental and Clinical Endocrinology & Diabetes, 2011, vol 109 (2) pp 135-148
5. Legro, Richard S. MD., et al., Detecting insulin resistance in polycystic ovary syndrome: purposes and pitfalls, Obstetrical & Gynecological Survey, Feb 2004, vol 59 (2) pp 141-154
6. Escobar-Morreale, H.F. & Millán, Abdominal adiposity and the polycystic ovary syndrome, Trends in Endocrinology & Metabolism, September 2007, vol 18 (7) pp 266-272
7. NHS, Obesity, NHS website, 2016, accessed 12/2/19
8. Ying Lee, C.M., et al., Indices of abdominal obesity are better discriminators of cardiovascular risk factors than BMI: a meta-analysis, Journal of Clinical Epidemiology, July 2008, vol 61 (7) pp 646-653
9. Teede, H.J. et al, Longitudinal weight gain in women identified with polycystic ovary syndrome: results of an observational study in young women, Obesity, July 2013, vol 21 (8)
10. Rey-López J.P., et al., The prevalence of metabolically healthy obesity: a systematic review and critical evaluation of the definitions used, Obesity Review, July 2014, vol 15 (10) pp 781-790
11. Kim, J.J. & Choi, Y.M., Dyslipidemia in women with polycystic ovary syndrome, Obstetrics & Gynecology Science, May 2013, vol 56 (3) pp 1377-142
12. Goyal, M. & Dawood, A.S., Debates regarding lean patients with polycystic ovary syndrome: a narrative review, Journal of Human Reproductive Sciences, 2017, vol 10 (3) pp 154-161
13. Arduc, A., et al., Should insulin resistance be screened in lean hirsute women? Gynecological Endocrinology, 2015, vol 31 (4) pp 291-295
14. Kirchengast, S., & Huber, J., Body composition characteristics and body fat distribution in lean women with polycystic ovary syndrome, Human Reproduction, June 2001, vol 16 (6), pp 1255-1260
15. Goyal, M. & Dawood, A.S., Debates regarding lean patients with polycystic ovary syndrome: a narrative review, Journal of Human Reproductive Sciences, 2017, vol 10 (3) pp 154-161
17. Teede, H.J. et al, Longitudinal weight gain in women identified with polycystic ovary syndrome: results of an observational study in young women, Obesity, July 2013, vol 21 (8)
18. Kiddy D.S., et al., Improvement in endocrine and ovarian function during dietary treatment of obese women with polycystic ovary syndrome, Clinical Endocrinology, 1992, vol 36 (1) pp 105-111
19. Unfer, V., et al., Effects of myo-inositol in women with PCOS: a systematic review of randomized controlled trials, 2012, Gynecological Endocrinology, vol 28 (7), pp 509-515