Polycystic ovarian syndrome (PCOS) is a condition characterised by multiple cysts in the ovaries which can impair ovulation and therefore fertility. One common feature of the condition is raised levels of the ‘male’ hormone testosterone, which can lead to ‘masculinising’ side effects such as ‘hirsutism’ (abnormal, excessive hair growth), scalp hair loss, and acne.
Another key underlying biochemical feature of PCOS is raised levels of insulin, usually related to ‘insulin resistance’ (impaired functioning of insulin). There is some thought that insulin acts on the ovaries to stimulate testosterone production.
One nutritional approach to PCOS is to take dietary steps to reduce insulin levels. This, in effect, means reducing in the diet carbohydrates that liberate significant quantities of glucose into the bloodstream (and therefore stimulate significant surges in insulin). At its heart, this is a ‘low-carb’ diet made up ostensibly of meat, fish, eggs, nuts, seeds, non-starchy vegetables and a little fruit such as berries. Not only does this sort of diet seem to help improve some of the biochemical imbalances typically found in PCOS, it often leads to weight loss too.
However, not all women with PCOS are overweight, but may nevertheless have features such as insulin resistance, raised testosterone and ovulation issues. I was very interested to read about a recent study in women with PCOS but normal body weight in whom two different diets were trialled . In this study, it was not the ‘macronutrient’ make-up of the diet that was being tested (e.g. low fat v low carb), but the phasing of food intake.
In this study, 60 women were randomised to eat the same diet in one of two ways:
1. a 980 calorie breakfast, a 640 calorie lunch and a 190 calorie dinner
2. a 190 calorie breakfast, a 640 calorie lunch and a 980 calorie dinner
The trial lasted 90 days.
Neither group lost weight, but there were significant differences in several other measurements, all of them favouring the first regime (big breakfast, small dinner).
Some of these beneficial changes included:
- a 54 per cent reduction in levels of insulin
- a 50 per cent reduction in levels of free (active) testosterone
- an improvement in the frequency of ovulation
I think these results are impressive, and deserve attention. As I stated above, I believe the best diet, overall, for women with PCOS is one which is relatively low in carbohydrate. What this new study suggests is that the phasing of food intake can be important too, and there is evidence that benefits may be had from having a ‘breakfast like a king, lunch like a prince, and dinner like a pauper.’
1. Jakubowicz D, et al. Effects of caloric intake timing on insulin resistance and hyperandrogenism in lean women with polycystic ovary syndrome. Clinical Science 2013;125(9):423
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