Does a Ketogenic Diet Affect Women's Hormones?

Fact-checked by Dr. Anthony Gustin, DC, MS.

Written by Joanna Cailas

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Does a ketogenic diet affect women’s hormones? Yes—you can count on your nutrition to affect your hormones. Does it ruin or destroy your hormones? No.

The unfortunate part is that if women rely on hearsay and don’t source better information about ketosis and their hormones, they lose out on the benefits of ketosis, especially those who suffer from PCOS, endometriosis, and uterine fibroids. Women with these conditions can benefit significantly from the ketogenic diet. [1]

In this post we’ll discuss the ketogenic diet’s impact on your thyroid and the HPA axis, then look at ways to evaluate your hormones, how you feel, and what adjustments to make.

The Ketogenic Diet and Your Thyroid

Is ketosis bad for your thyroid? No. Let’s break it down:

  • It’s true that low-carb diets (like the ketogenic diet) and calorie restriction lowers T3, the thyroid marker hormone. [3] [4]
  • T3 make your cells use more energy. Because of its function, scientists have hypothesized that “a reduction in T3 hormone may increase lifespan by conserving energy and reducing free-radical production.” [4]
  • Together with T4, these hormones regulate your metabolism, heart rate and body temperature. Most of T3 binds to protein and some free T3 circulates in your blood.

But a lowered T3 doesn’t mean you get thyroid dysfunction or hypothyroidism.

Hypothyroidism is often a case of high levels of TSH (thyroid stimulating hormone) and low levels of free T4. The pituitary gland tries to get your thyroid gland to produce T4: high levels of TSH. But the thyroid isn’t responding: low levels of T4.

When T3 is reduced, the thyroid is called “euthyroid.” A normal thyroid. For a more in-depth look at what a low-carb diet does to T3, T4 and TSH levels, read Dr. Anthony’s article on ketosis and women’s hormones.

Ketosis, the HPA Axis, and Cortisol

The HPA axis is the triumvirate of hormonal production: the hypothalamus secretes hormones and talks to the pituitary and adrenal glands into doing their jobs toward producing those hormones.

  • No, ketosis does NOT mess up your HPA axis. The opposite is true: the genuinely ketogenic diet may actually benefit the HPA axis; it helps with better hypothalamic stimulation. [5]
  • There is no evidence that a ketogenic diet affects the HPA pathway in any way. Data shows that ketone signaling uses a different (and probably more efficient) pathway. [6]
  • Hypothalamic neuropeptides, superior mechanisms for hypothalamic stimulation, are clearly extremely elevated in a ketogenic diet. Studies show that ketones cross the blood brain barrier and act as signaling molecules on hypothalamic neuropeptides. [5]

The ketogenic diet and cortisol:

Cortisol is the notorious stress hormone but it starts out innocently. When you’re under stress, cortisol taps into protein stores and produces glucose for your body to use to flee or fight the stress. Good thing, right?

  • But consistently high cortisol levels means consistently high stress levels, and your body and brain starts to tire.
  • All that extra glucose means elevated blood sugar, which leads to all sorts of problems.

Because the ketogenic diet leaves the HPA axis unaltered or potentially improved, then cortisol–produced within the adrenal gland– is fine. In fact, cortisol levels are low for those in ketosis, [7] or completely unaffected. [8]

If you feel particularly bad, here are a few points to consider:

Are You Overtraining?

Think of your priorities. Is it performance with your HIIT 3+ times a week? Or achieving ketosis?

If you go for both, you are overtraining. This may lead to cortisol levels shooting up (your body is stressed from what you’re putting it through) and other hormonal problems. Overtraining is the root cause of it, [9] not ketosis. A ketogenic diet may not be the best match for rigorous training goals.

Here are a few symptoms of cortisol elevation [10] and other hormonal issues caused by overtraining: [11]

Symptoms of Hormonal Issues Caused by Overtraining

Are You In Ketosis?

You are in ketosis when AND ONLY WHEN you meet this condition: your body is breaking down fat into ketones as an energy source. How do you know this? By testing your ketone levels. Pee sticks and breath meters are not accurate because ketones are in your blood.

You use a blood meter like the one used to measure blood glucose. Prick your finger for a drop of blood and set the machine to tell you your BHB (beta-hydroxybutyrate) levels. In ketosis, your measurement would be consistently above 0.5, without using exogenous ketones.

Eating high-fat and low-carb but not in keto

High fat and low carb diets don’t feel good.

If you’re on such a diet because you’re starting keto, you may feel terrible before you achieve ketosis. This is called the keto flu. Your body is changing gears and protesting a little. Do things properly and you may avoid the keto flu.

There’s no comparison between ketosis and a ‘low-carb/high fat but non-ketogenic’ diet [6].

The ketogenic diet regulates energy in an entirely different way [6] and breaks through the blood-brain barrier, which means your brain gets fed, and feeding your brain means improved mental acuity and physical energy. You feel great, like you can do anything!

Are You Eating Enough?

Stick around long enough and you’ll read/hear stories about how being in ketosis helps so much with intermittent fasting (IF). People don’t get hungry or crave food like they used to and have no trouble following their fasting schedule. [12]

But make no mistake, keto-ers who do IF for its benefits are fastidious about measuring their calories and eating enough when they eat. Because calorie restriction only makes you feel bad, and is proven to affect hormones negatively, especially in women. [13] [14] In this case, it’s not ketosis making you feel bad. It’s your starvation.

Measure your ketones, measure your food intake, and make sure it’s adequate to the demands of your day.

Are Your Hormones Out of Whack Already?

If your periods have always been bad, or if you have chronic pain you can’t explain (back ache, severe headaches), you may have hormonal imbalance, which needs correction and consultation with your doctor before you do something drastic as undertaking the ketogenic diet. If already in ketosis, SEE YOUR DOCTOR if you’re concerned about any drastic changes like amenorrhea (lack of menstruation), clotting, pain, etc.

Keto and your periods: what to expect (and not to expect)

  • You may get your period back after having experienced an irregular flow most of your life
  • If you’ve been in birth control, and stopped or removed the device, or a natural amenorrhea (for athletes and breastfeeding mothers), your period may go back with a heavy flow to start.
  • You may get heavier than usual bleeding, lasting for more days than before. Once your body adjusts and compensates for all the changes in estrogen levels and body fat storage and use, everything would go back to normal, or better than before
  • Ketosis doesn’t cure bloating. While most other PMS symptoms get better or get done (back ache, cramps, etc), bloating remains. It’s due to the massive surge of estrogen in that part of your cycle.
  • Hormones affect your insulin sensitivity. Blood glucose surging or dropping is normal. After your period, it should get back to normal.
  • If you’re hungry, eat. After ovulation, your body prepares to pump out estrogen and progesterone—which can cause hunger. Go for keto-friendly chocolate, keto mug cakes, fat bombs, or go take home the bacon or the steak.

Check out this article from Wicked Stuffed for tips on keto for women, especially for that time of the month.

Are You Stressed?

Stress can lead to hormonal problems, especially in women, and managing stress may help solve those problems.  [15] [16]

Instead of rigorous training, aim for light movement like yoga, and try meditating, walking and journaling to take control your anxiety and stress levels. When your stress is persistent enough, you need medical intervention.

To Sum It Up:

The ketogenic diet, in and of itself, doesn’t affect women’s hormones in a negative way.

Hormonal imbalance has other root causes:

  • Pre-existing hormonal imbalance (not caused by keto)
  • Hypo or hyperthyroidism (also not caused by keto)
  • Overtraining
  • Not eating enough (you are starving)
  • Stress

These other causes need to be ruled out—and treated—before you and your doctor can conclude/diagnose a bad experience with ketosis—if you have actually been in ketosis.

Measure your ketones and make sure your caloric intake matches the physical demands you put yourself through. Go after healthy fitness goals and keep your stress levels down.

Wondering about how keto has affected other women when it comes to their periods, or in their senior years, during/after menopause? Lots of heartening answers in Ketogenic Forums and also in this Reddit thread. You would also find support and discussions in our Perfect Keto Community. For information about ketosis and pregnancy, go here.

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Responses (18)

  1. Re: Thyroid function, I was diagnosed with hypothyroidy about 21 years ago. It was another celiac symptom which was missed. Finally, after my daughter was diagnosed 4 years ago with celiac and I started researching I figured out that I was also celiac. (Diagnosis was confirmed with a blood test.)

    Although I had hopes that resolving the celiac issue and going grain-free/low-carb would help, only my recent commitment to keto AND IF has resulted in needing a reduced dosage of thyroid hormones. In all the years that I was on thyroid meds, I took 100 micrograms per day, or sometimes 800 per week, never less, even on natural thyroid. Now I’m down to 550 per week, and will keep trying to tweak the dosage lower. Keto and IF have been great for my hormone balance!

  2. I’m 63, menopausal and am trying to go keto. I no longer have my blood sugar bouncing all over and don’t have to carry a large amt of food to work. I still have lack of energy and not sleeping well. any suggestions for us older ladies km

  3. Morning you may want to look up Leanne Vogel (Healful Pursuit) she has a lot of great suggestions for “carb ups” for a restful night. Good luck!!

  4. I am post menopausal and hadn’t had my period for 22 months. I started Keto in October 2017 and was only on the diet for about 1 week when I got my period. I saw my OB/GYN and they have done an MRI, Ultra Sound and
    D&C. I have two fibroids in my utereaus both which are about the size of a tennis ball. I am in great health (54 years old) and did not have any symptoms of menopause. So, they are suggesting a partial hysterectomy. Can the Keto diet (being high in fat) cause increased estrogen? How can the Keto diet help fibroids?

  5. Hashimotos here, yes my t3 took a drop, will it balance out? I’ve been keto about 3.5 months, while my inflammation is down, my energy from t3 drop is down too. Help!

  6. Thanks for all of this! I can’t seem to find information about the lack of a period with women in my same age, fitness, and weight.

    I’ve been doing keto now since the end of July and my period initially started being very weird- showing up late, just a spot, or a full flow for 8 days. Now since November, I havent had one at all.

    I am 29 so not pre-menopausal, work out 5-6 times a week, weigh about 136lbs, 5’7″. Im going to start tracking my calories and macros again to double check im not in starvation mode (which I HIGHLY doubt I am) I still have body fat and have not dropped so low that my body would turn itself off.

    Anyways, Ive reached out to my doctor again to see what they recommend but im worried about 1. doing permanent damage 2. Is Keto ok for me to do?

  7. Hi. I had a hysterectomy and take a hormone replacement for hot flashes. Can being on this type of diet affect that. I’ve noticed that I’ve been so busy, I’ve missed my med 3 nights and no hot flashes.

  8. Look up Leanne Vogel, https://www.healthfulpursuit.com/
    She has several podcasts about keto diets and problems with your period. From what I remember, if you work out that much, you probably need more food. Listen to her podcasts, you will learn so much and she presents the info from a woman’s perspective.

  9. Hi,

    A friend of mine wants to be on keto, she suffers from hypothyroidism and takes 75mg tablet per day, to start keto should she stop the tablet totally or how please advice.

  10. Hello-

    I’m experiencing similar symptoms….late period….only lasts 1 day….did you figure out the root cause?

  11. Hi, just started a keto diet a few weeks ago in the hope it will help with a large fibroid and balance hormones. Has anyone else had any positive results in shrinking their fibroids being on a keto diet as I can’t seem to see any info on this topic, thanks.

  12. I’ve only been on LCHF diet for five days and two past days in ketosis (well, according to Ketostix anyway) – I’m 50. I was on my period whilst starting this (just random timing) and it is day 9 now & bleeding is getting heavier & heavier. Normally my period lasts 4-6 days and not heavy, always been like a clockwork since they started at 11. I have major hot flashes and then I’m cold, a bit of diarrhoea in the morning. I’ve added a bit more carbs but still under 50g; energy levels slowly returning I guess…have not worked out this week apart from walks (normally run, go to the gym). On my second day of LCHF I threw up excessively and my bowls pretty much emptied themselves (ha) and I had to lie in bed for three hours in cold sweat, then going through chills before finally feeling back to normal. Has anyone gone through this? I’m wondering if I should try and see a few more days or whether it could just be that this isn’t suitable for my body – the excessive period flow seems disturbing. Thanks!

  13. Thank you for this post about periods – I’ve been having heavier than normal irregular bleeding (nothing super heavy). I’ve had an IUD for a year and had VERY light periods up till now. I was worried, then just annoyed, then worried when it came back a week later, but this all makes so much sense! Thank you, thank you, thank you!!

  14. Hormones are a really important element to explore before undertaking a lifestyle change – as it can really have an impact on what changes should be considered and will work for you. Looking after yourself is the most important thing and understanding as much as you can about your body is a big part of that!

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