Low-GI diet helps women with PCOS, but is there something that might work better?

Polycystic ovarian syndrome (PCOS) is a condition characterised by multiples cysts in the ovaries, but also other symptoms such as hirsutism (abnormal hairiness) and acne that may result from higher than normal levels of androgens (‘male’ hormones) in the female body. I wrote about this condition back in 2003 (see here), where I made the point that the best diet, generally speaking, was one based on low glycaemic index (low GI) foods – i.e. foods that release sugar relatively slowly into the bloodstream.

One of the rationales here is that women with PCOS tend to be insulin resistant. In other words, their insulin tends not to work so well. The chief function of insulin is to reduce blood sugar levels. So, if insulin isn’t working too well, it makes sense to avoid eating foods that cause spikes in blood sugar. Also, there is an idea that higher levels of insulin (common in insulin resistance) can stimulate androgen release. At the time, the idea of eating a low-GI diet was based on common sense and first principles. Recently, though, a group of scientists decided to test the merits of low-GI eating in the real world [1].

96 women started the study, and were assigned to either a low-GI diet or a ‘healthy’ diet. Both diets made half of their calories made up from carbohydrate. For each diet, calories contributed by protein and fat were the same too (23 and 27 per cent) respectively. The overall GIs of the two diets were 40 and 59 respectively. The study lasted for 12 months.

A number of measures were taken as part of the study including body composition, sex hormone levels, and blood sugar control (as assessed with an oral glucose tolerance test).

Compared to the group eating the standard diet, those eating the lower-GI diet saw significant improvement in the results of the glucose tolerance test, which would point to improved blood sugar control and insulin action.

Also, 95 per cent of women saw improvement in the regularity of their menstrual cycle, compared to 63 per cent of the other group. Overall, the lower-GI group did better, in other words.

This study provides some objective evidence that a low-GI diet has merit for women with PCOS. However, my advice for women with PCOS looking to improve their condition through diet is not to eat a low-GI diet, but to eat a low-carb one. The thing is, it is possible to eat a low-GI diet and still eat a lot of carb. And, in essence, the less carb someone eats, the less insulin they secrete and, in theory at least, the better the result.

I used to be a fan of low-GI diets (and still am, on some levels). However, over the years I’ve become convinced that for many, low-GI diets just don’t go far enough. This is not just true for PCOS, but for other issues too including excess weight and type 2 diabetes.


1. Marsh KA, et al. Effect of a low glycemic index compared with a conventional healthy diet on polycystic ovary syndrome Am J Clin Nutr 19 May 2010 [epub before print]

18 Responses to Low-GI diet helps women with PCOS, but is there something that might work better?

  1. Dave 20 May 2010 at 7:33 pm #

    Besides, it’s basically impossible to know whether or not you’re really eating “low GI”, since effective glycemic index depends on a number of factors, such as food combinations. The only way to be sure you’re actually eating low GI is either to measure blood sugar after every meal (not a bad idea anyway to understand how your body responds to different foods) or to just minimize carbohydrate across the board.

  2. Kirsty 21 May 2010 at 3:22 pm #

    Great article, thanks! I was diagnosed with PCOS around 15 years ago and had the usual symptoms – extra hair growth on my face, weight gain, bad acne and very irregular periods (normally only 3-4 per year). However, around 18 months ago I started a low-carb diet (basically I cut out bread and only had small amounts of potatoes and pasta), joined a gym and started mountain hiking, cycling and walking – I have since lost 5 1/2 stone, my skin is almost clear and my periods are bang on schedule (once a month). I’ve had to had laser hair removal treatment for the extra hair but I definitely noticed improvements even before I started that treatment. I would highly recommend PCOS sufferers try low-carb – it worked for me and I’ve never felt better 🙂

  3. Candy 21 May 2010 at 11:13 pm #

    I have recently, in my late twenties, been diagnosed with PCOS after many years of having spots and excess hair. I had no idea that I had PCOS, having never been overweight nor have I suffered irregular monthly cycles, I just thought that these symptoms were “normal” for me.

    It wasn’t until I underwent some kinesiology treatments for another health matter (back trouble) that I put two and two together. Time and time again during the kinesiology treatments “left ovary:low progesterone” would come up. I found this fascinating and visited my GP and subsequently had a blood test which did indeed confirm PCOS.

    I am currently supplementing with magnesium, chromium, zinc and selenium (will be throwing some copper into the mix, also.)

    I don’t believe that PCOS is a “done deal”, infact I feel incredibly positive about reversing the condition with the aid of the above supplements and the removal of most carbs, especially refined carbs from my diet (easier said than done!)

    I didn’t know of kinesiology’s existence before I had the treatments, so went into it with my eyes wide open. I am now a firm believer in it and used the aforementioned blood test as a way of backing up my belief in kinesiology. I decided from the off that I would not be going down the route of the birth control pill and metformin, no matter how much the GP’s tried to persuade me that it would be the best thing for me. And try, they did!

    I really do feel that the way to treat PCOS is with supplements and removal of carbs from the diet. Big Pharma need not be involved!

  4. maja 22 May 2010 at 10:59 am #


    Can someone recommmend a good low carb book/cookbook please?

  5. Abigail 25 May 2010 at 1:46 am #

    Maja, get Dr Briffa’s new book Waist Disposal. It has fabulous advice and has some great recpies.

  6. maja 26 May 2010 at 5:51 pm #

    Thanks Abigail,

    I was thinking of getting it for my hubby but I will definetely get it now!

  7. Nadia Mason 2 June 2010 at 12:09 pm #

    Really interesting article. I have found success recommending the low GL diet (rather than low GI) for PCOS. This takes into account the actual amount of carbohydrate in food, rather than just the type of carbohydrate.

    The advantages of carbohydrate foods also need to be recognised however – as dietary fibre and phytonutrients can also have a role to play in addressing PCOS.

  8. Flowerchica 18 November 2010 at 1:56 am #

    I’ve always thought that women with PCOS need to embrace a low GI diet. I thought the principal behind it was to avoid foods that are likely to cause blood sugar spikes. Since women with PCOS are not necessarily diabetics, I don’t know if the degree of blood sugar control is as important as making sure that you have a dietary lifestyle change. It’s also known that exercise can increase insulin resistance as well. I don’t think doing a low GI diet with no exercise will help at all.

    On another note, since so many women with PCOS are on metformin / glucophage, they really can’t eat a lot of foods that are not low-GI for fear of severe gastrointestinal side effects. So that’s another reason to embrace the low GI diet.

  9. Old-Timer 28 March 2011 at 7:48 pm #

    To CANDY:

    You’re recently diagnosed, so I can see your optimism. I was the exact same way. No amount of self-medicating (diet, exercise, vitamins, herbs) helped for more than a short period of time. Your problem is NOT diet and exercise, your problem is lack of progesterone as well as insulin resistance.

    That goes for all of you.

    Diet and exercise is wonderful, and you should pursue that 100%, but it will not cure it alone. There is no cure. You ARE stuck with this for the rest of your life. The only people I’ve ever heard of being “cured” from PCOS are anecdotal stories on the internet, no one has ever been documented to have cured themselves.

    Sorry guys, but open up those eyes of yours a little wider. Being open minded means also considering what your health practicioner can do for you in addition to what you can do for yourself. If you are so lucky to have health care, then TAKE ADVANTAGE OF IT. I don’t have any, and if it weren’t for the (awful) birth control pills, I would have died of blood loss, and almost did. I was stubborn and thought I could ‘cure’ or ‘manage’ it myself.

    You can’t.

  10. Tamara Locke 12 April 2011 at 11:20 pm #

    They are now saying it’s better to eat low-glycemic LOAD than low-glycemic index. this page explains

  11. Hugo 24 April 2011 at 4:11 pm #

    Hi Low GI diet is OK but something one must consider as well as the phytoestrogens you get from whole grains and soya that will aggravate PCOS by even increasing the estrogen levels more ! Just a thought to consider. Search on the net for tempeh – a fermented soya product that you can make yourself and there is a site that gives away a free starter (almost like making yoghurt) although I can’t remember the site now

  12. Amy 29 January 2012 at 10:20 pm #

    Wow, Old Timer. I’m sorry that in your experience the more natural ways of managing your condition didn’t work completely. I am a firm believer in trying less invasive first (unless it’s an emergency situation where you need the heavy-duty stuff) and then adding medical intervention if and when it’s necessary. Most of our health problems in this country are due to unhealthy lifestyles. Many people wait till it’s too late to change their lifestyle, and the damage is already done, hence the need for medication to manage conditions. Genetics also plays a role, so I’m not placing blame on any particular person with a medical condition. But the more you can do to improve your nutrition and lifestyle, the healthier you will be in the long run. I think you should be careful in your blanket statements, when you say nutrition and exercise are never enough. As a healthcare professional I’ve seen many people come off all their medications when they started eating well and exercising. To say that these choices can’t cure a condition like PCOS is ridiculous. Will they work in every case? No. Nothing does. Medication does not work in every case either.

  13. Morgan 11 January 2013 at 12:53 am #

    I have been considered as a potential PCOS sufferer for years, but only received a confirmed diagnosis when I started seeing the Reproductive Endocrinologist a month and a half ago for annovulatory cycles. My first GYN who thought I MIGHT have PCOS put me on Metformin, and told me that if I was indeed Insulin Resistant, then the glucophage would help me lose weight, and quickly at that. It turned out that I was allergic to the glucophage, and instead of losing weight, I continued to gain it. I gain at a regular rate of 7lbs a year, with little to no variation, which means that – in spite of trying Atkins, South Beach, and Weight Watchers- I have gained 100lbs in the past 14 years (roughly half my life). I recently decided to get serious about my weight loss goals in hopes of pushing my body back to ovulation, and was directed to Low GI and Low GL diets by my doctors, as well as through my personal research. I have JUST started a Low GL diet- I don’t eat white potatoes, I eat only whole grain bread or pasta in moderation, and long grain rices, reduced fat dairy in moderation, and no raw sugars, but pushing to eat 7 servings of veggies or fruit by the end of the day. In just a few weeks, I have already seen a major change in my weight. I have averaged slightly less than a pound of loss a DAY. I am increasing my water intake, so that is part of the loss, but I never expected to see results so soon- in one week, pants that I was getting ready to give away were suddenly able to button again, and I can SEE my upper abdomen flattening. It has made a huge difference in my life. I am getting ready to add pilates to the mix, so I imagine that will slow things down as my body readjusts. I just wanted to emphasize that while low-carb is a helpful tool for weight loss, the Low GI and Low GL diets may work better for some, because you don’t feel restricted, and as long as you’re pushing to get those veggies in, you won’t have enough space in your stomach to go bingeing throughout the day. 🙂

    • Nikki 17 April 2014 at 5:28 pm #

      Morgan, thank you for sharing. That was really helpful information and encouraging as well 🙂

  14. Ashley 13 June 2013 at 5:56 am #

    This article is helpful, especially in regards to how a change in diet can specifically help someone with PCOS. However, where it states that low-GI diets can allow higher carbs (which is true) and recommending that PCOS sufferers instead focus on low-carb diets, it must be said that one can successfully do BOTH a low-GI *and* low-carb diet simultaneously–these diets have a lot of shared recipes between them that meet both criteria, so the combination of both diets is easy to follow. Basically, increase your protein intake, and eat low-GI foods/cut out all forms of refined sugar. I’ve found it extremely effective with my PCOS symptoms and weight loss (87 lbs so far over the course of 7 months!). My periods are regular, the weight is steadily disappearing, my skin is clear and my periods are regular. It doesn’t have to be either/or when it comes to the low-GI/low-carb debate–it can be both! And it’s not as restrictive as one might think. There are so many easy and delicious recipes out there that meet both requirements.


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