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Weight Loss & PCOS

Weight loss is the first line of treatment for the majority of women who have PCOS, and for overweight women with PCOS, reducing fat levels dramatically changes hormone balance and improves fertility and birth rates. Losing weight also reduces the chance of other health conditions, including diabetes, hypertension, high cholesterol and heart disease.

  • A 5% reduction in body weight usually alters the hormone balance enough to normalise ovulation and make natural pregnancy possible
  • A 10% fall in body weight reduces body fat by 30%, resulting in nearly every PCOS woman ovulating normally! 
  • For women of 180lbs, that’s losing 18lbs

When obese women with PCOS follow a 1200 kcal/day diet:

  • Three-quarters lose 5% of their weight, and a third lose 10%
  • All women reduce their BMI, body fat, waist and hip circumferences
  • Ovaries significantly shrink in size, as do the number of “cysts” in them
  • Two-thirds of non-ovulating women resume regular cycles
  • A third become pregnant when they lose at least 5% of their weight

For many women, PCOS stems from problems with sugar metabolism and insulin resistance (this includes women of average weight) because high insulin levels stimulate the ovaries to produce testosterone. 

Genetics and the environment contribute to PCOS. Some ethnicities are more prone to insulin resistance on a Western diet simply because their forebears have adapted to low carbohydrate and sugar diets. Not everyone’s metabolism can cope with high carbohydrate diets or alcohol as well as many Caucasians.


“Diet” is an emotive subject, but the latest research is clear: for women with PCOS, a low-carb or ketogenic diet is the best way to:

  • Improve ovarian function and ovulation rates
  • Reduce the number of cysts
  • Lose fat weight and reduce one’s BMI
  • Reduce insulin resistance
  • Improve sex-hormone levels (increases in FSH and SHBG, reduced testosterone)
  • Reduce LDL (or “bad”) cholesterol levels
  • Improve pancreatic function
  • Increase the chances of getting pregnant

The relationship between PCOS and high insulin levels makes a diabetic-type diet ideal, but also bear in mind that:

  • Most women and adolescents with PCOS are malnourished. This may seem implausible, but their diet is often extremely restricted and lacks essential nutrients
  • PCOS rates fall when protein intake rises (we advise vegetable protein as much as possible). Vegetable protein encourages healthy gut bacteria that reduce inflammation and protect the gut
  • A low-carb diet reduces PCOS (and insulin resistance)
  • Weight loss is far more effective for obese and overweight women with insulin resistance and PCOS than metformin-type drugs

There are several concerns about adopting a low-carb diet for women trying to get pregnant:

  1. Is it safe? Generally, yes, as long as people are sensible and eat enough. However, we advise anyone with an AUTO-IMMUNE CONDITION OR DIABETES to discuss this diet with their MD/GP
  2. Won’t hunger be a big issue? Strangely, not really; carbs fuel hunger, and after the first week, appetite falls dramatically
  3. Won’t energy be an issue? Energy is unlikely to be an issue unless you’re a serious athlete! Published research supports this type of diet for chronic fatigue and fibromyalgia i

How does it work?

  1. Mitochondria are tiny structures inside cells that burn sugar and fat to provide energy
  2. The mitochondria in all cells (except heart muscle) choose sugar before fat as an energy source. Burning sugar first may be the body’s way of getting rid of dangerous sugar (we know it’s the cause of many chronic diseases)
  3. Fatty acid molecules generate over 3x as much energy as glucose molecules and create significantly less oxidative stress

How to do it

Going on a low-carb keto diet WILL reduce body fat and weight. Cutting out wheat, potatoes, rice, etc., is a daunting prospect, but it is achievable, and you’ll have it worked out within a week. It will alter your hormone balance and gut microbiome, so expect to be pretty grumpy for a week or so!

  1. Find out what to eat or avoid: there are many online guides, but we particularly like the one by HealthLine. It involves eating as many non-root vegetables as possible, and an exciting challenge is to see how many you can eat in a day!
  2. Get some decent scales: we recommend a “body analyser” that tracks weight, fat, protein, water, etc. They are worth the extra cost, and seeing the changes occur helps reinforce your motivation!
  3. If you’re aiming for mild ketosis, buy a breathalyser. There are many online; breathe shallowly and repeat 2-3x to get accurate readings, and avoid food or drink for 20 minutes before use
  4. Avoid beer and wine, but spirits are OK (within reason)
  5. Drink a lot of water to help flush out toxins released from fat stores
  6. Keep exercising, as not exercising creates problems with the mitochondria

Have a clear idea of your target weight, track your keto measurements and, since you’re turning yourself into an experiment, why not do BBT tracking as well? BBT provides lots of helpful information on your hormones and the phases of your cycle for you or a therapist.


i Targeting mitochondrial dysfunction in the treatment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) – a clinical audit (nih.gov)
Photo by i yunmai on Unsplash