Lower carb diet trumps higher carb one in women with polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a condition characterized by the presence of cysts in the ovaries. It can lead to problems with infertility as well as higher-than-normal levels of ‘male’ hormones called ‘androgens’ including testosterone. One other common feature in individuals with PCOS is ‘insulin resistance’ – impaired ability for insulin to do its job which can lead to, among other things, raised levels of sugar (glucose) in the bloodstream.

There has been some interest in nutritional circles in the value of a low-carbohydrate diet or a low glycaemic index diet (a diet based on food that release sugar relatively slowly into the bloodstream) in the management of PCOS. As I wrote about here, my preference in practice is for a low-carbohydrate diet. Less carbohydrate will generally mean less insulin which can help insulin functioning in time. Also, by and large, I do find low-carb diets most effective for weight loss, and excess weight is a feature in many (though not all) women with PCOS.

I was therefore interested to read a study published on-line this week which pitted two diets – one high in protein and low in carbohydrate, and the other containing less protein and more carbohydrate – in women with PCOS [1].

In this study, the ‘high protein’ diet group was to consume a diet that consisted of >40% of energy from protein, 30% of energy from fat, and <30% of energy from carbohydrates. The goal here was to replace sugar and starchy carbohydrates with vegetables, fruit, nuts, and more protein. Protein sources were mainly meat, eggs, fish, and dairy products.

The higher-carbohydrate and lower-protein diet was intended to consist of <15% of energy from protein, 30% of energy from fat, and >55% of energy from carbohydrates (which was to include sugar and starchy carbohydrates).

The individuals were allowed to eat as much as they liked of the permitted diets (the diets were ‘ad libitum’ in nature). The study lasted six months.

The amount of reported food eaten by the two groups was essentially the same. However, the effects of these diets was markedly different.

Average weight loss in the higher protein diet was 7.7 kg compared with less than half of this (3.3 kg) in the higher-carbohydrate eaters.

Average fat loss was 6.4 kg v 2.1 kg. In other words, the higher-protein group lost and average of 3 times as much fat as the higher-carbohydrate eaters.

Blood sugar levels were a little better in the higher-protein eaters, and this was statistically significant. The authors of the study concluded that “… the replacement of carbohydrates with protein in ad libitum diets improves weight loss and improves glucose metabolism by an effect that seems to be independent of weight loss and, thus, seems to offer an improved dietary treatment of PCOS women.”

References:

1. Sørensen LB, et al. Effects of increased dietary protein-to-carbohydrate ratios in women with polycystic ovary syndrome. Am J Clin Nutr epub 8th December 2011

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