What is the best dietary approach for women with PCOS?

There are a range of dietary approaches that women with polycystic ovary syndrome (PCOS) can try for weight management. They involve modifying the amount of type of carbohydrate, protein or fat in your diet. There is limited high quality evidence assessing these diets in PCOS. The research generally shows no differences in weight, reproductive, metabolic (risk for diabetes or heart disease) or psychological (quality of life) outcomes for different types of diets. For this reason, it is recommended that weight management (weight loss or prevention of weight gain) should occur in the setting of healthy food choices. When considering changing your diet to manage or lose weight, it is important that you research the diet first.  Ensure that the diet you are trying provides adequate amounts of nutrients, vitamins and minerals and is consistent with the Australian Dietary Guidelines.

Unfortunately there does not seem to be any one dietary approach that is ‘best’ for women with PCOS. This means that if you have tried one in the past, and did not find it useful for weight management, there are other options available to try.  Seek the advice of an Accredited Practising Dietitian (APD) if you are in any way confused or concerned about which dietary approach is best for you.

The Australian Dietary Guidelines

Enjoy a wide variety of nutritious foods

• Eat plenty of vegetables, legumes and fruits
• Eat plenty of cereals (including breads, rice, pasta and noodles), preferably wholegrain
• Include lean meat, fish, poultry and/or alternatives
• Include milks, yoghurts, cheeses and/or alternatives. Reduced-fat varieties should be chosen where possible
• Drink plenty of water

and take care to

• Limit saturated fat and moderate total fat intake
• Choose foods low in salt
• Limit your alcohol intake if you choose to drink
• Consume only moderate amounts of sugars and foods containing added sugars

Following these guidelines will provide adequate levels of fibre, nutrients, vitamins and minerals. When you are trying to lose weight it is important to make sure that you have an adequate nutritional intake. You also need to be careful of energy dense foods and drinks such as processed and takeaway foods and soft drinks that are high in kilojoules, sugar or fat.

It is also important to maintain a lower fat diet, and to limit the ‘bad’ fats (saturated fats) in your diet by choosing low fat dairy products and lean meats, reducing processed foods such as cakes, pastries, biscuits, chips and fried take-away foods and using unsaturated oils and margarines in moderation. Look at both the quantity and the quality of the food you are eating, and watch portion sizes of meals and snacks. The guidelines also emphasise the need to prevent weight gain by being physically active and eating according to your energy needs.

Depending on how much exercise you do and how much you weigh, eating 5000-8000 kJ/day is suitable for weight loss. As a rough guide, to lose 0.5-1 kg per week, you need to be eating 2250-4500 kJ less than you are expending (using up) each day, but slower loss achieved through more moderate changes is usually easier to sustain. It is easier to maximise weight loss if you both increase the energy you expend (through exercise) and reduce the energy you take in (through having a healthy diet).

Low Glycaemic Index or Low Glycaemic Load diets

Alternative options that are popular for women with PCOS include diets that lower the glycaemic index (GI) or glycaemic load (GL). This is a measure of the type of carbohydrate in the diet.

• Carbohydrates with a low glycaemic index (GI) produce less of an increase in glucose levels and insulin levels in the blood after they are eaten
• Glycaemic load (GL) refers to the overall impact of foods on blood glucose over the course of an entire day, based on both the GI of each carbohydrate ingredient and the carbohydrate content of each food.

A lower GI or GL diet is commonly used for people with diabetes and can reduce risk factors for heart disease. There is some evidence that a low GI or GL diet can reduce hunger and help improve weight loss long-term. However, it is not clear if a low GI or GL diet specifically reduces insulin resistance.

There is limited evidence specifically assessing the role of a lower GI or GL diet in women with PCOS. An Australian study (Marsh et al, Am J Clin Nutr. 2010 Jul;92(1):83-92) compared a low GI diet to a standard healthy weight loss diet in overweight women with PCOS. While women lost similar amounts of weight on either diet, women following the lower GI diet had greater improvements in insulin resistance and menstrual function. Although these findings are promising, almost 50 per cent of the women did not complete the study. More research is needed to find ways to make diets and lifestyle programs easier for women with PCOS to follow long-term to maintain weight loss.  

A low GI diet is still a healthy approach consistent with the Australian Dietary Guidelines and can be a useful alternative, particularly when followed with other principles consistent with the guidelines such as increasing fruit, vegetable, legume, lean meat and low fat dairy and reducing fat, saturated fat, added salt and added sugar intake.

Higher protein diets

Diets with an increased protein intake have recently been studied both in overweight people with increased risk for heart disease and type 2 diabetes, and in overweight women with PCOS.

In general, the Australian Dietary Guidelines recommend a moderate protein intake of approximately 15-20 per cent of your daily energy intake. An increased protein diet contains approximately 25-35 per cent of your daily energy intake.

In overweight people who are at risk for heart disease and type 2 diabetes, a high protein diet has been shown to lead to reductions in risk factors for these conditions. There is some evidence that weight loss can be improved due to the protein reducing hunger levels.

In overweight women with PCOS, high protein diets have been compared to high carbohydrate diets (similar to the Australian Dietary Guidelines) in a number of small studies. In two small studies, similar reductions in weight and insulin levels were reported after two to four months. In the first study (Moran et al, J Clin Endocrinol Metab. 2003 Feb;88(2):812-9), the higher protein diet led to greater reductions in glucose levels after eating, greater reductions in male hormones (androgens) and a better level of high density lipoprotein cholesterol (‘good’ cholesterol); however, these advantages were not evident in the second study (Stamets et al, Fertil Steril. 2004 Mar;81(3):630-7).

A third study (Kasim-Karakas et al, Fertil Steril. 2009 Jul;92(1):262-70) reported greater reductions in weight and cholesterol levels for the higher protein diet. However, in this study the higher protein intake was achieved through adding a high protein supplement to a standard weight loss diet. This approach may not be as easy to follow in a non-research environment. A higher protein intake therefore might have some benefits for women with PCOS but is not necessarily the best or only approach to follow.

Very low carbohydrate diets

There has been a great deal of interest in recent years in very low carbohydrate diets such as the Atkins diet. These diets contain typically 20-30g carbohydrate per day in the initial weight loss phases compared to an average daily carbohydrate intake for women of 150-250g carbohydrate per day.

Fat intake is generally much higher on very low carbohydrate diets, and protein intake is moderately higher. Although there is some evidence that short-term weight loss can be better on these diets, over a longer period (2-3 years) weight loss is generally the same or even worse than other approaches. These diets do not seem to reduce insulin levels as some other diets do. There is also some concern about the effect of this approach on risk factors for heart disease. Long-term use of these diets is currently not advised.

Summary

Overall a better balance of energy intake (diet) and output (physical activity) is the only way to lose weight. Short-term ‘fad’ diets should generally be avoided.

Further resources

Books

The CSIRO Total Wellbeing Diet (Book 2)

Fact sheets

External links

Dietitians Association of Australia - http://www.daa.asn.au/

Nutrition Australia - http://www.nutritionaustralia.org/

Content updated 26 August 2011