New study suggests specific phasing of food can help women with PCOS

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 [1]. 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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7 Responses to New study suggests specific phasing of food can help women with PCOS

  1. gibsongirl 16 August 2013 at 2:24 am #

    I am a 60yo woman. I am diabetic (T2-no meds), hypothyroid, PCOS. I actually happened into the meal setup you describe and it works. I put about five hours between meals and the last one is very light. I feel better, have lost a few pounds (still overweight) and now my labs are all normal. I have been eating very low carb for about ten years and I found that I can include more vegetables and fruit with no rise in HbA1c since making breakfast more substantial.

  2. Modesty 16 August 2013 at 9:44 am #

    Not surprised since Dietdoctor already have reported on several cases where women on LCHF became fertile again –

  3. T 16 August 2013 at 11:38 am #

    But that this study also suggest that guys should avoid “having a ‘breakfast like a king, lunch like a prince, and dinner like a pauper’” lest we also get “a 50 per cent reduction in levels of free (active) testosterone”!!??

  4. William L. Wilson, M.D. 16 August 2013 at 12:19 pm #

    It would be interesting to see how this type of diet would affect men, particularly in the area of hormones. I suspect this pattern of eating wouldn’t have the same effect on testosterone levels as in this study because the T level changes in PCOS are likely pathological, not physiological.

  5. Melinda Ma 16 March 2014 at 12:31 am #

    I am 36. have been diagnosed with PCOS but I have always been underweight and have difficulty gaining. (I am guessing heredity is a factor in my low weight.) I have found eating a low carb (high protein) diet to improve the regularity of my cycles. However, I find it difficult to eat enough calories and would like to gain weight. I am also guessing phasing as this article suggests would not help me gain weight. Any ideas how to gain weight on a low carb diet?

  6. Robert Park 16 March 2014 at 2:04 pm #

    I am at an advanced stage to life and weight gain and dieting has been a constant feature and indeed, still is, and further more, experimenting too has been part of this setting. I was a vegetarian for 17 years which culminated in having to have an emergency quadruple by-pass (1990) and thereafter my diet was predominately protein with lashings of fat on which I felt good and my health was restored. Two features which have affected me since is that of after lunch tiredness, and more lately, plummeting energy levels. I also retained a healthy libido until about two years ago when it too plummeted but still exists. Initially I blamed those symptoms on longevity that was until lately when again, on experimenting with dieting I noticed that a meal solely of fresh fruits, yoghurt, with added glucose, made me feel remarkably well and without the tiredness and plummeting energy levels. After about three days on this diet my waist band felt slacker and interestingly my libido has much improved. This feel-good factor was not experienced with green salads except that there was no tiredness afterwards. On each occasion after having a cooked or processed-food meal, about thirty minutes later I felt tired when my energy would plummet. This effect is fascinating and I am wondering why it should occur especially as carbs are believed to raise the blood sugar levels and can have a detrimental effect on health and which is contrary to my reading and experience to date.

  7. Diana Deco 24 March 2014 at 1:54 am #

    Robert Park, check out Dr Robert Lustig’s “Sugar: The Bitter Truth”. He reckons that its fructose that’s the problem, not glucose. It gets a bit confusing, because obviously fruit has some fructose, but there’s lots more in sugar (half glucose, half fructose) and high-fructose-corn-syrup. So I guess fruit, yoghurt and glucose might fit in with his ideas?

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