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As a dietitian who specializes in women’s health & hormones, the question I’m probably asked the most is: “Which diet is best for PCOS?” Closely followed by “Should I try keto for PCOS?”

There’s so much information (and misinformation) out there. For every woman who swears the keto diet “cured” her PCOS, there’s another dozen who swear by Weight Watchers…or Whole30…or a vegan diet…or Crossfit…or, or, or….

So, what’s the deal? What actually works?

In my previous article series on polycystic ovary syndrome (PCOS), we’ve covered what PCOS is, why it’s so hard to lose weight when you have PCOS, how to control PCOS naturally with diet and lifestyle, and important nutrients for women with PCOS.

In this article series, we’ll take a look at the pros and cons of some popular diets for PCOS…and why this dietitian doesn’t think you should follow “a diet” at all.

Let’s start with the bane of my existence: Keto.

Bring on the haters.

What it is and How it Works

The keto diet is an extremely low-carbohydrate diet designed to force your body to burn fat for fuel in the form of ketones. Less than 5% of daily calories come from carbs, 75-80% come from fat, and the rest come from protein.

Your brain doesn’t like using ketones for fuel (it prefers glucose), but in the absence of carbs, it would rather use ketones than, say, stop working.

Eating low-carb has been shown to lower blood sugar and insulin levels, and may improve insulin resistance.

With insulin resistance being one of the underlying drivers of PCOS, trying keto for PCOS seems like a no-brainer, then, right?

Don’t put your brain away just yet….

Because it eliminates all grains and starchy vegetables and limits the amount of non-starchy vegetables and fruits you can eat, keto causes some other problems.

The Keto Diet Increases Belly Fat

First, the adrenal glands produce cortisol in response to stress. Any stress.

Your body perceives the stress of potential starvation EXACTLY THE SAME WAY as it perceives a wooly mammoth chasing you down a frozen tundra. It does not know the difference.

When you don’t give your body enough carbs, it worries that you’re about to go into a famine.

In response, it wants to protect you from wasting away. So, it tells the adrenals to pump out cortisol.

Cortisol raises your blood sugar, raises your insulin, and  increases insulin resistance.

High blood sugar and insulin levels mean you can’t tap into that stored body fat to burn. And an increase in cortisol leads to an increase in belly fat.

Not exactly what you had planned, right?

This is why some women actually gain weight on keto. And they gain it in the middle, which is metabolically more unhealthy than gaining weight on your hips or thighs. So keto may not be the greatest idea for PCOS…

The Keto Diet Causes Hormone Issues

Because you’re missing out on fiber, that’s going to slow your roll when it comes to having regular bowel movements.

Do you know what happens when you don’t poop every day? Excess hormones & toxins build up in your body.

Additionally, meat is full of hormones. All the bacon & sausages you’re eating? They are adding to your overall hormone load.

Just what someone with PCOS doesn’t need is more hormone issues. So that’s another check in the “cons” column for keto for PCOS.

The Keto Diet is Low in Nutrients

You’re also missing out on vitamins, minerals, antioxidants, and phytonutrients from all of those colorful fruits & veggies you’re not eating.

Antioxidants help fight inflammation…which is another underlying issue with PCOS.

Granted, it’s possible to eat an anti-inflammatory–style keto diet, but from what I hear on the street (aka, see on Instagram), most people following a keto diet aren’t loading their plates up with wild-caught salmon, walnuts, flaxseeds, or avocados.

For realz, though, one of my grocery store customers told me he’d been following keto for the last 9 months by eating 4 slices of bacon for breakfast, 4 slices of bacon for lunch, and a steak or chicken for dinner. He literally hadn’t eaten a single vegetable in 9 months.

(Here’s where I’ll insert a gentle plea: If you feel you absolutely MUST try the keto diet for PCOS to see if it works for you, please, please, please work with a registered dietitian to ensure you are meeting your nutrient needs.)

While we’re on the subject of nutrients…

The Keto Diet is Not a Fertility Diet

Antioxidants improve egg health for the mama-to-be and sperm health for the daddy-to-be. The keto diet is extremely low in antioxidants.

Ideally, for fertility, you should be aiming for 8-10 servings of colorful fruits and vegetables a day. The restrictive carb count of keto does not allow for this many servings.

And if you do manage to conceive, do you know what a baby needs most in the first trimester?

It’s not fat, protein, carbs, or even calories.

It’s micronutrients (aka vitamins & minerals).

Doing a keto diet while you’re trying to conceive is dangerous to baby’s health.

So again, I implore you…if you’re following keto to drop weight quickly to qualify for IVF or a similar situation: Stop the diet at least 3 months prior to trying to conceive. And take a high-quality prenatal if at any time while following keto you may become pregnant.

The Keto Diet Messes with Your Microbiome

As previously mentioned, the keto diet is extremely low in fiber. This affects not only digestion, but also the microbiome.

We’re learning more about the microbiome every day, but in all honesty, we’re still in the “we don’t even know what we don’t know” phase of research.

Studies have suggested that the microbiome can affect mood, weight, and many other outcomes you wouldn’t normally think of as connected to gut health.

And studies have suggested that women with PCOS already have a disturbed microbiome. Keto isn’t going to help that.

But the science is very clear that if you want a healthy microbiome, you should get fiber from a wide variety of plant foods. The more variety of foods, the healthier the assortment of bugs in your gut.

Keep those buggers happy…we don’t even know yet all the good things they’re doing for us.

Weight Loss is Mostly Water Weight

In your muscles and liver, carbohydrates are stored in the form of glycogen. For every 1 gram of carb, there are 3–4 grams of water.

You use up these stored carbs pretty quickly when you eliminate carbs from your diet.

And with them goes the water weight. Like overnight.

But as soon as you so much as lick a carb, that weight will come right back on as your body works to replenish its stores.

People often gain back all the weight they lost plus more the second they go off a keto diet.

(Here’s where the haters will come in and tell me they’re never going off it, because “it’s a lifestyle”! Really? It’s a pretty sad lifestyle, IMO. But you do you.)

It’s Not Sustainable

While studies give the keto diet a slight edge in weight loss versus a low-fat diet at 6 months, by one year, there is no difference in weight loss between the two diets.

Additionally, the diet is extremely repetitive and easy to get bored with.

In fact in the one scientific study that exists on keto for PCOS (which was in 12 women, btw), only half of them were still on the diet at the 3-month point.

Seriously, are you never going to eat a bagel again? Pizza? A banana?  Ever? (We can’t be friends.)

Carbs are freakin’ delicious. And life is long. And should be full of pleasurable eating experiences. And things like birthday cakes and shared ice cream cones with loved ones.

The keto diet kills your sense of hunger, I know. But it’s part of being a human being to feel your hunger and then satisfy that hunger with food that fills your soul as well as your belly.

In that regard, the keto diet is basically one step above sucking down a Soylent shake every 6 hours.

Counting Every Gram of Food is No Way to Live

As unthinkable as giving up carbs forever is, the thought of counting every frickin’ gram of food you eat for the rest of your life just makes me so sad.

Think about all the things you could do with the time you gain back if you stop weighing, measuring, logging, and obsessing over every bite you eat.

Not to mention peeing on expensive sticks to check whether you’re in ketosis and ingesting pricey and dubious exogenous ketone products.

I recently read something about the keto diet that basically said, “if you have to pee on a stick to make sure you’re following your diet correctly, you’re not.”

Figuring out how to eat doesn’t have to be so hard. Another con for keto for PCOS.

The Bottom Line

There are a ton of “success stories” out there about losing weight on a keto diet. Just look at the number of keto-focused Instagram accounts.

I guaran-goddamn-tee that 6 months from now, 95% of those accounts will be shut down and replaced by the next wave of people following the keto plan. (Coincidentally, the diet failure rate is about 95%).

Or maybe the trend will have moved on to something else by then. Who knows?

But for now, the negatives outweigh the positives when it comes to keto for PCOS.

If you’re ready to start taking control of your PCOS
with the help of a registered dietitian who addresses
the root causes of your symptoms, check out my PCOS services here. 

So instead of keto for PCOS, what should you do?

  • Eat real food

  • Minimize added sugars

  • Emphasize colorful fruits & veggies

  • Balance carbs with protein and healthy fats

  • Eat high-quality, unprocessed animal foods

  • Enjoy a treat every now and again

It’s that easy.

Stay tuned for future articles on other popular diets.

IMPORTANT NOTE -> This information is provided for educational purposes and should not be construed as medical advice. Please consult with your healthcare practitioners before undertaking any changes in your diet or adding supplements. 

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