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There is literally an infinite number of diets to choose from, and a new one popping up every month, so which one is the right one for women with PCOS in 2023?
In short, the best diet for women with PCOS is a low inflammatory diet using the validated dietary inflammatory index.
This makes sense as PCOS is a low-grade chronic inflammatory condition. Therefore, the best diet for women with PCOS trying to lose weight is a hypocaloric low inflammatory diet.
Let’s have a look at the evidence. To date, several diets have been trialled in women with PCOS. These include:
⦁ Low carb diet
⦁ Low fat diet
⦁ Mediterranean diet
⦁ Ketogenic diet
⦁ Low inflammatory diet
Low carb diet
As explained by Barrea et al., high carbohydrate intake and low-grade inflammation cooperate with insulin resistance and hyperandrogenism to exacerbate the severity of PCOS. With 65-80% of women with PCOS being resistant to insulin, this makes a low carb diet (< 26% carbohydrates) particularly important.
A meta-analysis of low carb diet studies involving women with PCOS reported significantly reduced BMI, androgen and insulin resistance levels along with improved lipid (fat) metabolism after just 2 months without necessarily reducing calorie intake.
Low fat diet
Contrary to recent high fat diets success in many studies, high fat diets are not suitable for women with PCOS. This is because saturated fat increases inflammation and insulin resistance much more in women with PCOS, than women without PCOS, irrespective of BMI, which leads to increased androgen production by the ovaries. In the study which reported the greatest benefit of a low fat diet in women with PCOS, saturated fat intake was restricted to just 6 grams per day, with no more 30 grams per day in total fats.
The Mediterranean diet is an anti-inflammatory diet, rich in complex carbohydrates and fiber, and high in monounsaturated fats. A link between adherence to the Mediterranean diet and the clinical severity of PCOS was first reported in 2019 during an observational study. In 2022, a larger and more comprehensive study confirmed the original finding suggesting that the Mediterranean diet plays a protective role in women with PCOS.
So what effect does changing to a Mediterranean diet have?
In a 2022 study published by Mei et al. 59 obese women with PCOS were randomly allocated one of two energy-restricted diets (<1400Kcal/day), the Mediterranean low carb diet or the low fat diet, for a period of 12 weeks. At the end of the trial however, women who underwent the Mediterranean low carb diet had a more significant improvement in weight and body measurements, sex hormones and metabolic parameters (Table 1).
|Mediterranean low carb||Low fat|
|Total testosterone (ng/mL)||−0.20||+0.08|
|Fasting plasma glucose (mmol/mL)||−0.50||+0.05|
|Fasting insulin (μU/ml)||−8.5||−4.9|
|Total cholesterol (mmol)||−1.5||−0.4|
|LDL cholesterol (mmol)||−0.7||−0.4|
In addition to these improvements, more than 70% of participants restored their normal menstrual cycle (irrespective of diet) by the end of the trial.
The ketogenic diet is a very low carb, high fat diet that activates ketosis, a metabolic state which utilises fat and ketones for energy. Unfortunately, saturated fats are especially unhealthy for women with PCOS. This is evident when comparing 2 studies which featured women with PCOS undergoing different ketogenic diets. The modified ketogenic diet lower in saturated fat (1.5% vs. 39%) achieved a similar reduction of fat mass in less time (6 vs. 12 weeks) and improved metabolic outcomes significantly more than the traditional ketogenic diet.
Low inflammatory diet
A low inflammatory diet is based on the dietary inflammatory index (DII) which scores 45 different food parameters according to their pro or anti- inflammatory effect. In two completely independent studies, both research teams concluded that a high DII increased the risk of PCOS, suggesting a low inflammatory diet is beneficial in women with PCOS. This is not surprising given PCOS is an inflammatory condition.
Upon reviewing the dietary inflammatory index, we notice a familiar pattern. Saturated fats, trans-unsaturated fats, total fats, energy, cholesterol, carbohydrates and vitamin B12 (found in animal foods) are all pro-inflammatory, in order of highest to lowest. In fact, a low inflammatory diet very much resembles a low carb and fat type of Mediterranean diet.
A Tip From Fertility Science
Without overly complicating diet plans, here are 5 things you can also do to really boost the impact of your diet on PCOS according to science:
- Control calorie intake
- Select low GI foods
- Restrict eating to an 8-hour period
- Avoid snacking or skipping breakfast
- Supplement your diet with vitamins and minerals
As obvious as it sounds, controlling calorie intake is important for women with PCOS as simply overeating is inflammatory on the body.
Secondly, low GI foods such as pulses (i.e. split-peas, dry beans, lentils, and chickpeas) is one of mother nature’s superfood for PCOS. These seeds are high in fibre, low in fat and contain complex carbohydrates with a low GI. Women with PCOS who modified their diet to include 2 pulse-based meals per day, without any change in calories, significantly improved their metabolic profile after just 4 months (Table 2).
|Pulse-Based Diet||Therapeutic Lifestyle Changes Diet|
|Total insulin AUC (µIU/mL × min)||−121||−27|
|Diastolic blood pressure (mmHg)||−3.6||−0.2|
|LDL cholesterol (mmol/L)||−0.2||0.0|
|HDL cholesterol (mmol/L)||+0.1||−0.1|
|Total cholesterol/HDL cholesterol||−0.4||+0.1|
Restricting eating to an 8-hour period each day (i.e. intermittent fasting) is also beneficial to women with PCOS. In a recent small trial, just 5 weeks of intermittent fasting (4pm to 8am) saw women with PCOS lose an average of 1.3kg in weight, 3.6kg of fat mass, decrease fasting insulin levels, improve hormone profile, inflammation, liver health and menstrual cycles (in 11/15 women).
This ties in with the next recommendation which is to avoid snacking or skipping meals. Snacking between meals inadvertently reduces the bodies ‘fasting period’ which can lead to insulin resistance while skipping breakfast disrupts the female reproductive hormones. In fact, snacking and skipping meals is linked to menstrual disorders in both women with and without PCOS.
Finally, women with PCOS are often deficient in several vitamins and minerals which disrupt various systems in the body and aggravates PCOS. Fortunately, addressing any (remaining) deficiencies with supplements after dietary changes usually corrects this and reduces the severity of PCOS even further.
Łagowska K and Pieczyńska J M, (2022). Not only diet quality and physical activity but also snacking and skipping meals could be related with menstrual disorders in PCOS. https://doi.org/10.1080/03630242.2022.2106529
Mei S, et al. (2022). Mediterranean Diet Combined With a Low-Carbohydrate Dietary Pattern in the Treatment of Overweight Polycystic Ovary Syndrome Patients. https://doi.org/10.3389/fnut.2022.876620
Oyelowo O, et al. (2022). Skipping the first active meal appears to adversely alter reproductive function in female than male rats. https://doi.org/10.1016/j.crphys.2022.10.001
Oh R, et al. (2022). Low Carbohydrate Diet. https://pubmed.ncbi.nlm.nih.gov/30725769/
Wang Q, et al. (2022). Higher dietary inflammation potential and certain dietary patterns are associated with polycystic ovary syndrome risk in China: A case-control study. https://doi.org/10.1016/j.nutres.2021.12.006
Cincione R I, et al. (2021). Effects of Mixed of a Ketogenic Diet in Overweight and Obese Women with Polycystic Ovary Syndrome. https://doi.org/10.3390/ijerph182312490
Li C, et al. (2021). Eight-hour time-restricted feeding improves endocrine and metabolic profiles in women with anovulatory polycystic ovary syndrome. https://doi.org/10.1186/s12967-021-02817-2
Sharkesh E, et al. (2021). The dietary inflammatory index is directly associated with polycystic ovary syndrome: A case-control study. https://doi.org/10.1111/cen.14672
Gonzalez F, et al. (2020). Inflammation Triggered by Saturated Fat Ingestion Is Linked to Insulin Resistance and Hyperandrogenism in Polycystic Ovary Syndrome. https://doi.org/10.1210/clinem/dgaa108
Paoli A, et al. (2020). Effects of a ketogenic diet in overweight women with polycystic ovary syndrome. https://doi.org/10.1186/s12967-020-02277-0
Barrea L, et al. (2019). Adherence to the Mediterranean Diet, Dietary Patterns and Body Composition in Women with Polycystic Ovary Syndrome (PCOS). https://doi.org/10.3390/nu11102278
Zhang X, et al. (2019). The Effect of Low Carbohydrate Diet on Polycystic Ovary Syndrome: A Meta-Analysis of Randomized Controlled Trials. https://doi.org/10.1155/2019/4386401
Barrea L, et al. (2018). Source and amount of carbohydrate in the diet and inflammation in women with polycystic ovary syndrome. https://doi.org/10.1017/s0954422418000136
Kazemi M, et al. (2018). A Comparison of a Pulse-Based Diet and the Therapeutic Lifestyle Changes Diet in Combination with Exercise and Health Counselling on the Cardio-Metabolic Risk Profile in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial. https://doi.org/10.3390/nu10101387
Wong J, et al. (2016). A randomized pilot study of dietary treatments for polycystic ovary syndrome in adolescents. https://doi.org/10.1111/ijpo.12047
Shivappa N, et al. (2014). Designing and developing a literature-derived, population-based dietary inflammatory index. https://doi.org/10.1017/s1368980013002115
Rupa Vani K, et al. (2013). Menstrual Abnormalities in School Going Girls – Are They Related to Dietary and Exercise Pattern? https://doi.org/10.7860/JCDR/2013/6464.3603
Fujiwara T, et al. (2009). Skipping breakfast adversely affects menstrual disorders in young college students. https://doi.org/10.1080/09637480802260998
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