Regardless of how much you weigh, diet and exercise are both key to managing PCOS, and recommended as the first things to address when looking to improve symptoms and optimise your long term health (1,2). Current research highlights the importance of maintaining a healthy weight to manage symptoms. Research (1) shows that for women with PCOS and a Body Mass Index (BMI) of more than 25kg, losing as little as 5% of your total body weight can significantly improve the following:
- Excessive hair growth (the medical term for this is 'hirsutism')
- Testosterone levels
- Insulin levels
- Don't cut out carbohydrates, just swap them. Look at the foods you eat that fall into the medium or high GI groups and swap them to low GI alternatives. For example, instead of eating mashed potato which has a high GI of 83, swap it for sweet potatoes which can have a low GI of 44.
- Lower the overall GI of a meal by eating fruits or vegetables at each meal or as snacks during the day. This is a good tip too if you're eating out - you can order a side dish of vegetables or salad with no dressing, or make your own with lemon.
- Include at least one low GI food at every meal.
- Snack on low GI foods and make sure they're available when you need them. Low GI snacks include vegetables with houmous, fruit and some nuts, such as cashews and peanuts.
Reducing caloric intake and eating healthily is recommended to help reach, and maintain, a healthy weight however, there isn’t a consensus about the type of diet that women with PCOS should follow. With no single diet yet proven to work for all women with PCOS, it can be confusing to know exactly what you should and shouldn’t be eating.
Diet and exercise have both been shown to be key to improving symptoms
A growing body of research indicates that a low glycemic index (GI) diet is beneficial (3). Many books have been published with useful information on diets for women with PCOS, including the 'PCOS Diet Book: How you can use the nutritional approach to deal with polycystic ovary syndrome' by Colette Harris and Theresa Chung, and 'The Low GI Guide to Managing PCOS' by Professor Jennie Brand Miller and Nadir Farid. The British Dietetic Association has also published a fact sheet on managing PCOS through diet and exercise, and they too recommend a low GI diet.
What is a low GI diet?
Carbohydrates seem to be revered by some but it’s important to know the facts to make informed decisions about dietary choices, especially because of the impact it can have on PCOS symptoms. We all need carbohydrates, proteins and fats: carbohydrates mainly for energy; protein which performs a range of vital functions such as producing hormones, body tissue maintenance and supporting our immune function; and fats (the healthy unsaturated type) to aid the absorption of some vitamins and insulate your body.
All carbohydrates are broken down into glucose but different carbohydrates have different effects on our blood sugar levels. The glycemic index, GI, considers the quality of the carbohydrate. It ranks carbohydrate foods from 1 to 100 and categorises them as low, medium or high GI according to their immediate effect on blood sugar levels. The glycemic load (GL) is another measure, looking at both the quality and quantity of a carbohydrate, and ranks the amount of carbohydrate in a food serving.
The higher the GI of a food, the higher the blood sugar level after eating it. High GI foods of 70 or more convert quickly to glucose causing your blood sugar levels to rise and fall quickly. It's therefore likely that you'll become hungry quickly after eating high GI foods and crave more sugary foods. You're also more likely to store excess calories as fat when you have more insulin in your blood which is explained further in the next section. Low GI foods of 55 or less however, release glucose slowly into the bloodstream, keeping your energy levels in balance and making you feel fuller for a longer period of time.
How can a low GI diet help women with PCOS?
Regardless of their weight, a lot of women with PCOS are insulin resistant. To understand this better, we need to look at the role of insulin and the part it plays in PCOS.
Insulin is a hormone produced by the pancreas. It's released every time you eat foods with glucose such as sugary foods or processed carbohydrates. Your body will use the glucose for energy immediately, store it for later, or convert excess amounts into fat.Insulin is so important because it helps to keep our blood sugar levels balanced. It also increases testosterone levels, which women need small amounts of, but excessive amounts can lead to hormonal imbalances and cause excessive hair growth, menstrual and skin problems. If you regularly eat sugary foods and high GI processed carbohydrates, your body will release so much insulin that it will begin to lose its sensitivity to it. Unfortunately, women with PCOS can have this reduced insulin sensitivity, called insulin resistance, because of the condition.
Regardless of their weight, a lot of women with PCOS are insulin resistant
Insulin resistance means that the cells are literally resistant to normal levels of insulin - they just don't hear the signals and don't respond as quickly. As your cells think there is a reduction of insulin, your body tries to keep your blood sugars normal by releasing larger and larger amounts of insulin to move glucose into the cells. Your body basically stops producing the correct amounts of insulin and blood sugar levels rise. This process results in compensatory hyperinsulinemia, an excessively high level of insulin in the blood, which can damage cells and lead to all sorts of problems, such as weight gain, hormonal imbalances, type 2 diabetes and cardiovascular disease.
Whether you need to lose weight or not, eating low GI foods can have an array of health benefits for the whole family. Combined with exercise, eating low GI foods results in lower glucose levels after eating, which reduces the demand of insulin. This, in turn, can lower cholesterol and decrease the risk of diabetes and heart disease.
What can you eat on a low GI diet?
If you're interested in learning more about eating a low GI diet, there is lots of helpful information available. For example, Dr. Jennie Brand-Miller, an Australian nutritionist and authority on the GI, has written many books, one of which is 'The Low GI Diet: Shopper's Guide to GI Values'. There's also a wealth of information at the University of Sydney's website where you can search the GI of any food and find recipes. The Glycemic Index Foundation, a charity formed by The University of Sydney and JDRF Australia, also has a website full of useful information and resources.
Here are some tips from Positive PCOS on how to follow a low GI diet:
References & Information Resources
Note that referenced or mentioned authors, websites and organisations are not affiliated with, nor endorsing, the content published on Positive PCOS.
1: The Jean Hailes Foundation for Women’s Health on behalf of the PCOS Australian Alliance. 2011. Evidence-based guideline for the assessment and management of polycystic ovary syndrome. Copies available to download at www.jeanhailes.org.uk
2: A.H. Balen & J. Rutherford. 2007. Managing anovulatory infertility and polycystic ovary syndrome. British Medical Journal. 335: 663-6
3: K. Marsh et al. 2010. Effect of a low glycemic index compared with a conventional healthy diet on polycystic ovary syndrome. The American Journal of Clinical Nutrition. 92: 83–92
Y.M. Jeanes. 2009. Dietary management of women with polycystic ovary syndrome in the United Kingdom: the role of dieticians. Journal of Human Nutrition & Dietetics. 22: 551–55