A low fat (~30 per cent of energy, saturated fat ~10 per cent of energy, <300 mg cholesterol daily), moderate protein (~15 per cent) and high carbohydrate intake (~55 per cent), in conjunction with moderate regular exercise is recommended by a variety of institutions for the management of obesity and related co-morbidities^{24, 33-35}. This is a nutritionally adequate approach when followed in conjunction with the Australian Dietary Guidelines.

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

There is increasing interest in alternative dietary approaches to weight loss both for targeting weight gain and treating excess weight, insulin resistance and reproductive and metabolic abnormalities in PCOS. These approaches include high protein (Zone diet, CSIRO Total Wellbeing diet), low carbohydrate (Atkins diet) and low glycemic index or low glycemic load diets. In the general population, there is increasing research on alternative dietary approaches for weight management. As yet, there is limited evidence to suggest that one dietary approach is optimal for long-term weight loss. A comparison of the Atkins diet, Ornish diet (very low fat), Weight Watchers and Zone diet showed similar weight losses and dietary compliance over 12 months³⁶.

There are two small studies assessing high protein weight loss diets in PCOS (~4200-6000 kJ/day over 1-4 months with diet compositions of 30 per cent protein, 30 per cent fat and 40 per cent carbohydrate or 15 per cent protein, 30 per cent fat and 55 per cent carbohydrate). Equivalent reductions in weight (3.6-7.5 per cent), fasting insulin and reproductive hormones and improvements in reproductive parameters were observed for both the high and moderate protein approaches^15,37.

Very low carbohydrate diets have been studied in two small uncontrolled studies in women above their healthy weight with PCOS. Although in these studies significant weight losses and reduction in fasting insulin or testosterone occurred over six months, these diets were not compared to a conventional approach and their comparative success of these strategies cannot be determined. The effect of changing carbohydrate type or glycaemic index or glycaemic load on weight management and reproductive and metabolic parameters in PCOS has not yet been studied.

This indicates that as yet there is no one specific dietary approach that is ideal for treatment of PCOS and that a range of approaches, as long as they are safe and nutritionally adequate, can also give similar improvements in weight and reproductive features. Again, the important issue is that health benefits will be greatest if weight loss is achieved and maintained and an alternative dietary approach will only be useful if it is sustainable in the long-term (Table 1).

Content updated August 18, 2008