Intermittent Fasting for PCOS [Why it Helps + How to Do It]

Intermittent fasting for PCOS

PCOS (polycystic ovary syndrome) is a common hormonal disorder among women of childbearing age. 

Not only does it cause substantial health problems (similar to diabetes), it can also be really frustrating for women who are trying to get pregnant.

The good news?

Once you understand the root cause of PCOS, it quickly becomes clear that intermittent fasting can be an effective way to treat the condition.

Today I’ll cover the basics about PCOS, and how it works. Then I’ll share some specific suggestions about how you can use fasting and/or low carb nutrition to improve (and potentially reverse) PCOS.

Let’s get started. 

What Is Polycystic Ovary Syndrome (PCOS) 

PCOS is a common condition, affecting roughly 10% of women in childbearing age.  It typically results in some combination of obesity, irregular menstrual cycles, skin discoloration, facial hair, acne, and infertility. 

The exact combination of symptoms varies a lot, and not every woman with PCOS is obese.  

PCOS symptoms

PCOS shares a lot of similarities with type 2 diabetes (the most common kind of diabetes).  For example, both of them are associated with obesity, both cause weird skin changes, and both are sometimes treated with the same medication (metformin).  

Perhaps most importantly, PCOS and type 2 diabetes share the same underlying cause.

What Causes PCOS?

Like type 2 diabetes, the root cause of PCOS is this:

Excessively high insulin.

Insulin is a hormone involved in growth and energy storage, and insulin goes up whenever we eat carbohydrates.

If we eat too many refined carbs too often, after a while we get something called “insulin resistance”That means insulin doesn’t work as well in our body anymore, so our pancreas has to pump more of it out to try and do the same job.   

What do I mean by refined carbs?  

Anything that started as a grain, starch, or sugar, and then got crushed up in a factory.  For example:  Sweets, white bread, white rice, pasta, potato products, most tortillas, soda, juice, and so on.

With severe insulin resistance, even our fasting insulin level is high. In other words, insulin doesn’t go down all the way to normal, even when we stop eating for about 8 hours.

Some Nitty-Gritty Details About PCOS Physiology (In Case You’re Interested)

This section is a little technical and potentially confusing, but I’ll try to simplify it.  

Women’s ovaries have many “follicles”, and during each menstrual cycle several of those follicles mature.  Then, one of the follicles becomes dominant, and releases an egg (that’s called “ovulation”, and it’s necessary to become pregnant).  

Turns out, insulin plays an important role in stimulating follicle maturation.  Basically, insulin coaxes follicles towards maturity, little by little.  

If insulin is too high, things get out of whack.  

Too many follicles get “promoted” at first, but then none of them becomes the dominant follicle. Thanks to all that insulin, there’s no ovulation, which means the woman can’t get pregnant. Hence infertility.  

High insulin is the root cause of PCOS

Later, those “stuck” follicles turn into cysts (instead of getting re-absorbed like they normally would).  That’s why it’s called polycystic ovarian syndrome.

Excess insulin also causes women to make too much testosterone, by directly stimulating testosterone production in the ovarian follicles.

Between the high testosterone and the lack of ovulation, the menstrual cycle usually becomes irregular, and less frequent.

Why Does Intermittent Fasting Help with PCOS?

This part is really simple.  

PCOS is caused by high insulin, and fasting brings the insulin levels down.  

As I mentioned above, insulin goes up whenever we eat food with carbohydrates, especially processed carbs. So if we avoid processed carbs, or avoid carbs altogether, or sometimes don’t eat anything at all (i.e. fasting), insulin will gradually come down.

If you have severe insulin resistance, it can take a long time (and perhaps a lot of fasting) for your insulin levels to come down to normal. But eventually, they will.

Is There Any Research Showing that Intermittent Fasting is Good for PCOS?

Like a lot of things related to fasting, there’s not much official research–partly because there’s not a lot of money at stake.  In other words, nobody’s gonna make a profit by confirming that fasting cures PCOS.  So it’s hard to get funding for the research.  

Here’s one paper discussing the physiologic mechanisms of how fasting could be beneficial to someone with PCOS.  

Despite the limited research, there are many individual stories about women with PCOS whose symptoms improved or went away after switching to low carb or doing some fasting.

For example, listen to Dr. Nadia Pateguana’s story in the video below, about herself and many of her patients who became pregnant after switching to low carb or fasting:

“For whatever reason, when women started a diet with me, if they had been struggling to get pregnant, suddenly they miraculously got pregnant.”  -Dr. Nadia Pateguana

(In other words, their infertility from PCOS went away.)

In addition to all the anecdotes, it’s also worth considering the potential risks and benefits:

What are the risks of fasting with PCOS?  Basically nothing.  

The upside?  A potential cure.  

When the risks are so minute, and the potential benefits so great, it’s obviously worth a try. 

(Especially with something like fasting, which is clearly beneficial to your health whether you have PCOS or not.)

Treating PCOS With Fasting and Keto

As soon as someone with PCOS reduces consumption of processed carbs, the condition often improves. Fasting can also accelerate the improvement.

Either approach can lower insulin to varying degrees.  So both are beneficial, and you can certainly use them in combination as well.

Here are a few specific recommendations about how to use fasting, or a ketogenic diet, to treat PCOS.

How to Treat PCOS With a Low Carb Diet

When changing any habit, it’s best to start small, and make things easy at the beginning.  

With that in mind, here’s a basic approach you could take, in a gradual easy fashion:

Step 1:  Cut out processed carbs, like white bread, pasta, sweets, french fries, potato chips, juice, soda, etc.  Do that for at least 2 weeks before moving on.  

You’ll probably notice some improvement from that change alone.  But when you’re ready…

Step 2:  Start counting your “macros”, including how many grams of carbohydrates you’re eating each day.  Gradually reduce the amount of carbs you’re consuming.

Don’t wean off the carbs too quickly, because you’ll go through some withdrawals.  That can make you feel a little uncomfortable, which is called “keto flu”.  So take it slowly.  

How Many Carbs Should You Eat When Doing Keto With PCOS?

In general, the lower the better. But there’s no rush, so ease into it.  

Perhaps something like this:

  • Week 1:  up to 150 grams of carbs per day
  • Week 2:  100 grams per day
  • Week 3:  75 grams
  • Week 4:  50 grams

Naturally, you’ll have to look up nutrition info as you’re doing this, to see how many grams of carbs are in each food.  As you get more familiar with different food options, it’ll get easier to keep track.  

Using low carb or keto to treat PCOS

Eventually, you can work your way down to about 30 grams per day, which is a typical cutoff for a ketogenic diet.  

Related Post: 47 Simple & Easy Keto Foods

Step 3:  Once you get your carbs pretty low, it’s also a good idea to measure your ketones, so you’ll know if you’re getting into ketosis or not.  

To measure your ketones, you can use some cheap urine test strips.  They’re not perfect, but good enough for a beginner.  

You could also get fancier and purchase a breath ketone meter, or even a finger stick blood meter.  But those are more expensive, and definitely not necessary when you’re starting out.  

By the way, I shared some additional details about how to gradually reduce your carb intake in my Easy Fasting Guide, so feel free to check that out as well.   

Intermittent Fasting for PCOS:  How to Do It

There’s no “perfect” approach, but any type of fasting is likely to help if you have PCOS.  

So start with whatever works for you, and try to make it easy at the beginning. 

Based on my research, here’s what I’d recommend:   

First, try to master basic time-restricted eating, like fasting for 13-15 hours per day (on most days).

For example, that’s like eating dinner at 7pm, and then not eating again till breakfast at 8 or 9am.    

There’s no rush to move on to the next phase.  Just wait until you get pretty comfortable with doing that more often than not.  

When you’re ready, mix in some days with 17 or 18 hours of fasting.  Try this a couple times a week for a month or two.  

Using intermittent fasting to treat PCOS

Once you have several weeks under your belt, go ahead and mix in some 24-hour and 36-hour fasts here and there, about 1-3 times per week.  

Those slightly longer fasts are great for boosting autophagy, which may help your organs to heal more quickly.  Like your ovaries in the case of PCOS.  

If you’d like more details, another good resource would be my blog post about how to lose weight by fasting. There, I walk you through step-by-step how to progress from short fasts to longer fasts, and the same general approach could be effective for someone with PCOS.

Measuring Your Progress

As time goes on, you’ll probably see a significant improvement in symptoms related to PCOS, if not a complete reversal.

Some of this you can detect yourself–like your body shape, weight, facial hair, or acne.  Other things would require a medical test–like your fasting insulin levels, or how many cysts are on your ovaries.  

Pregnancy is another possible outcome, so keep an eye on that as well. 🙂

Any of these changes can take time, so be patient and stay the course.  

Wanna Learn More?

If you or someone you know has PCOS, there’s a really good book you may wanna check out, called The PCOS Plan.  

That book was written together by Dr. Nadia Pateguana and Dr. Jason Fung. It contains a lot of specific advice about how to treat PCOS with a combination of low-carb eating and intermittent fasting.  It even has a collection of recipes.

Feel free to check out my podcast interview with Dr. Pateguana (or any of the video clips from it I’ve shared above).

And here’s one more option:

Another podcast interview, with some in-depth discussion about the physiology of PCOS & fasting.  Dr Fung and Dr. Bret Scher (a cardiologist) discuss the ins and outs of PCOS for about 9 minutes, ending with this quote from Dr. Fung (edited slightly for clarity):

If you’re a patient with PCOS, you don’t have to prove that it works in everybody, you only have to prove that it works in yourself. You can simply say, “I’m gonna try it for 2 months, and see what happens”.  If nothing happens, you haven’t lost anything.  But what if your disease completely goes away?  Then you’ve done something that all the drugs haven’t been able to do for you.

(Dr. Fung goes on to point out that in vitro fertilization is big business, there’s tons of money in it.  But in most cases with PCOS, there’s a much easier and cheaper solution than expensive fertility treatments.)

Lastly, I’ve also written a separate blog post covering several key points for women to know about when fasting.  Feel free to check that out as well.

Summary and Final Thoughts 

PCOS is a really common condition that causes a lot of health problems, and a lot of frustration for women.

Once you understand the cause (high insulin), it’s pretty obvious that intermittent fasting and low carb diets can help a lot!  Both of those approaches will lower insulin, which is the key to improving (or curing) the disease.

It probably took years to develop PCOS, so don’t think you have to cure it overnight. Take a gradual, sustainable approach to improving your lifestyle, and you’ll be more likely to succeed in the long run.  

If you’d like some additional guidance about how to take an easy, smooth approach to fasting (and low-carb eating), that’s one of the things I walk you through step-by-step in my Easy Fasting Guide.  So go ahead and take a look at that as well, if you haven’t already.

Hope it helps. 🙂

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Picture of Ben Tanner, PA-C

Ben Tanner, PA-C

Ben has been practicing as a physician assistant (PA, or PA-C, similar to a doctor) in emergency medicine, urgent care, and family practice since 2014. Since 2016, he has developed an avid interest in various forms of fasting, using it to improve his own health while helping friends, family, and patients do the same.