Keto is so hot right now. Ketosis is the new kale, paleo, and superfood trend all wrapped up into one. The keto trend is also impressive as it is making a somewhat complicated nutritional approach that provides tons of health benefits something buzz-worthy that is now getting attention.
However, because of the booming growth, everyone is jumping on the keto bandwagon and screaming their own opinion. The bad part of trend jumping, especially in the beginning, is that there is a massive imbalance between people who write about opinions versus people who write about facts.
What happens is one person will post or comment on the ketogenic diet some emotional statement (an opinion) with disregarding current research and biological mechanism (facts). Because there aren’t a lot of qualified facts about ketosis written on the internet in the beginning, more people write posts citing the preceding factless posts, and inaccurate opinion is parroted for eternity, or until the trend fades, without ever addressing said facts.
The misinformation attacks on the ketogenic diet hurt the “trend” and scare people away from actually using this nutritional approach to lower inflammation, lose fat, increase energy, treat cancer, diabetes, hypercholesterolemia, neurodegenerative disease and more. Don’t get me wrong, people can also overstate the benefits of ketosis, claiming it is a panacea for all health conditions when it is not. This also a problem, albeit not as pressing.
DOES KETOSIS AFFECT HORMONES?
The biggest current negative misinformation (myth) in regards to a ketogenic diet is that a state of ketosis will destroy women’s hormones.
This is easily the most common backlash that I get after people see me promoting a ketogenic diet. The evidence lies in the comments in this Instagram thread after I did a podcast with the lovely Girls Gone WOD crew. Also, if one were to listen to what I said, I covered the fact that ketosis is not for everyone, and how a ketogenic diet can go bad. I digress.
The main argument that needs to be squashed is this: a ketogenic diet ruins women’s hormones.
Hormonal problems in women aren’t fun and yes, they do exist. These problems result in low energy, bone loss, weakness, weight gain, amenorrhea, mood swings and more.
Contrary to popular internet opinion, ketosis is not the cause of hormonal issues.
The most frustrating part is that no one has any sound biological mechanism on why this would actually be a problem and just seem to be parroting someone else opinion, or just working on some vague correlative observations without understanding biological processes. The majority of the “evidence” that supports this argument is anecdotal, which carries with it plenty of flaws that I’ll get into shortly. Such are facts on the internet in the Information Age.
To be clear I’m not saying that nutrition can’t cause massive hormonal problems with women. I’m also not saying that a ketogenic diet is appropriate for everyone. What I’m saying is that a properly executed ketogenic diet has no observable negative effect on women’s hormones.
To address this we will first discuss the rationale and the argument people are making as to why ketosis leads to hormonal problems in women and why I think these arguments are invalid. Second, we’ll cover the reasons why people are actually experiencing hormonal problems and anecdotally attributing these problems to ketosis and the steps to resolve these issues if you are experiencing them.
First, the rationale that ketosis triggers hormonal problems in women is broken down into a pair of main arguments: Ketosis will ruin your thyroid and ketosis will ruin your hypothalamus/pituitary/adrenal glands.
Argument 1: Ketosis is bad for your thyroid
One main argument of why ketosis can screw up women’s hormones follows from the thought that “carbs are necessary for thyroid function,” because with lower carbs (and lower calories) we observe a decreased circulating T3 hormone. Science certainly supports this. A lowered thyroid marker (T3) is associated with the ketogenic diet, especially when paired with caloric restriction. (1) (2) (3)
We need to put two and two together though. There’s some reasonable confusion here for people who aren’t clear on the workings of the thyroid gland. The problem is people demonize this finding because they conflate lower T3 with thyroid dysfunction and hypothyroidism.
To be very clear, lowered T3 is NOT the same thing as hypothyroidism.
This will be a very simplified version of how the thyroid gland works, but you have different hormones at play that are measured to determine the activity of the gland and as such, you should probably have a very brief overview. Your pituitary gland secretes thyroid stimulating hormone (TSH), which stimulates the thyroid gland to produce thyroxine (T4). T4 converts to triiodothyronine (T3) and then T3 acts on peripheral tissues. TSH, T4, and T3 (among other markers) are measured as part of a thyroid panel. Again, the very simplified version here but I have no time to write an endocrinology class for you.
Hypothyroidism, a nasty hormonal dysfunction associated with fatigue, weight gain, hair loss, depression, irritability and more. Hypothyroidism is typically clinically diagnosed with high levels of TSH and low levels of free T4. Your pituitary gland is saying “Hey, thyroid, can you make us some more T4, we seem to be running low… please?” (increases TSH) but your thyroid gland says “Nah, I’m taking off for awhile, you handle it.“ (doesn’t secrete T4). Do you notice which form of thyroid hormone is not a part of this conversation? T3. T3 is the form that is decreased with hypocaloric, ketogenic diets. When only T3 is reduced, the thyroid is otherwise labeled as “euthyroid,” which means normal thyroid.
Not only do we see T3 lowering independently of normal thyroid function, but lower levels of T3 actually show benefit for being anti-catabolic, preserving muscle mass and improving longevity. (4) (5) (6) (7) (8) Lowered T3 with a concurrent increase in energy expenditure has also been shown. (9) This is not hypothyroidism. You’d have decreased energy.
Wait… are we sure that lower T3 is alright? Like, really sure? Yes. Lowering T3 is likely one of the mechanisms behind the data showing preserved lean tissue mass with a ketogenic diet, which is an awesome benefit of ketosis. (10) (11) (12) If you were suffering from hypothyroidism, you’d be losing muscle mass. (13) A low-carb, ketogenic diet has an isolating effect on T3 and no effect TSH or T4, so you’re not hypothyroid and your thyroid gland is working just fine. (14)
So again, no, you are not becoming hypothyroid if your T3 decreases. A low calorie, ketogenic diet selectively reduces T3 without effect on the thyroid gland as a whole.
This is also completely reversible as T3 returns to baseline after calories and carbs are added back in. Hypothyroidism doesn’t magically and immediately reverse if you have that problem. But if there is an abundance of benefits likely to be gained with lower T3, why would you want to reverse it on command?
This would be analogous to having your triglycerides lowered on a ketogenic diet, (15) which is beneficial, then being relieved to know that you can just increase them again. Whew! Glad you could get out of that mess.
Summary: Your thyroid functions normally on a ketogenic diet and you do not get hypothyroidism. Circulating T3 decreases, which is completely reversible, and probably beneficial.
Argument 2: Ketosis is bad for your HPA axis and other hormones
The hypothalamus is gland in your body that is responsible for secreting hormones. This also communicates with your pituitary gland and your adrenals, otherwise known as your hypothalamic, pituitary, adrenal (or HPA) axis. One of the main concerns is that a ketogenic diet messes with the communication of this hormonal system leading to utter chaos.
Studies have shown, with graphs, and write, verbatim, “…energy balance in animals on a KD (ketogenic diet) appears to be controlled by mechanisms outside of the normal hypothalamic pathways.” (16) There are things called hypothalamic neuropeptides which are clearly extremely elevated in a ketogenic diet and thought of as a superior mechanism of hypothalamic stimulation. There are also more studies that show that ketones cross the blood brain barrier and act as signaling molecules on hypothalamic neuropeptides. (17)
Please note that this metabolic adaption to increase hypothalamic neuropeptides does NOT happen when eating a high fat, low carb diet, which is not the same thing as a ketogenic diet. (16) This is very important and will be discussed later. Low carb does not mean ketogenic, and high fat does not mean ketogenic. Using ketones for energy means ketogenic.
If you’re measuring standard hypothalamic processes, there remains no evidence that a ketogenic diet affects this pathway in any way. The only thing data shows is that ketone signaling uses a different (and probably more efficient) pathway. (16)
It should be common sense that if the HPA axis function is unaltered and potentially improved, then cortisol should be fine. I’ve also gotten hate mail in which people claim ketosis increases cortisol. This is not true. (18) (19) This will also be covered later on.
Another closely related argument is that ketosis decreases leptin, a hormone related to satiety and energy regulation. An article saying that ketosis is terrible for women’s hormones argues that insulin (reduced in ketosis) is needed for leptin production. This is not true. (20)
Additionally, the findings of leptin modulation from ketosis are all over the map. Leptin is higher on a ketogenic diet (21) (22), wait it is lower (23), no wait it doesn’t change at all. (24) (25) Luckily, we do see that a ketogenic diet regulates energy metabolism at a higher rate and completely outside of the leptin system. (16) Therefore, I don’t find this argument convincing.
Meanwhile, it has been shown that female hormonal issues do indeed happen with weight loss mediated by calorie restriction, excessive stress, and high-intensity exercise. (26) We’ll get there a little later. No mention of ketosis here, even though I’ve seen this research article cited on a website as proof that ketosis is bad for females. smfh.
Summary: Ketosis acts on the hypothalamus in a completely different way than a non-ketogenic diet, with no conclusive data regarding reduction in hormonal activity in the HPA axis.
Ok, so those are my dissections of the arguments people are actually making about the mechanism. But what about all of those anecdotal stories of ketosis ruining hormones? People are observing negative consequences, for sure. Here I’ll lay out why people are having problems and why it has nothing to do with ketosis.
Problem With Ketosis and Hormones #1: You’re not actually in ketosis
Far and away the biggest problem with anyone saying that “ketosis didn’t work for me” and that it led to any negative effects is a super simple one: they weren’t in ketosis. People just guess that if they eat low carb, or high fat, they are in a state of ketosis. Low carb and keto are not the same things. High carb and diabetes are not the same things. Your body needs to actually be using the breakdown of fat (ketones) for energy for it to be in ketosis. You must test to make sure you’re in ketosis or else you really have no idea.
Why can’t you just guess? Actually using ketones for energy drastically changes your metabolism compared to just being “low carb” and high fat. (16) You are using completely different pathways in your body for different things and regulating energy in an entirely different way. (27) Being low carb and high fat but not in ketosis is a quick and easy way to feel like shit. (27) If you’re interested in more about this topic, I have an in depth article on how low carb and ketosis are not the same things.
But how do you know if you’re in ketosis? You have to test yourself. This isn’t a guessing game. Pee sticks and breath meters are inaccurate, you need to look at if ketones are actually in your blood. You’ll measure this in mmol and get a number, and this number needs to consistently be above 0.5 and not with the use of exogenous ketones. Taking exogenous ketones has benefits on their own, but it does not equate to being in ketosis. I have another guide on how to measure ketone levels here.
Additionally, people who do test but drop off after a week or two because they didn’t feel great probably weren’t even able to use the ketones for energy. If you’ve been eating carbs for your entire life, the receptors on your cells literally need to change to be able to utilize ketones effectively. It can take up to a few months to become completely “fat adapted”. Coincidentally this is what exogenous ketones can actually help with.
If you don’t actually know if your metabolism has shifted to an entirely different state, don’t be surprised if you don’t feel great. Additionally, don’t tell me that ketosis is the devil and almost killed you if you haven’t consistently measured your ketone levels for a decent enough period of time.
How to fix this problem: You must test to make sure you are actually in ketosis (>0.5 mmol). There is no getting around this. “Low carb” isn’t good enough.
Problem With Ketosis and Hormones #2: You’re Not Eating Enough
There is plenty of data that long term calorie restriction does mess up the regulation of hormones, especially in women. (28) (29) The problem here is that this has nothing to do with ketosis. There are also studies that while calorie restriction messes up hormones, ketosis specifically does not. (30) (39)
It can actually be tough to get enough food on a ketogenic diet. Hunger levels plummet on a ketogenic diet and people just generally forget to eat. (31) I’ve actually had problems with this myself. In my opinion, it is super difficult to get enough food on a ketogenic diet. But again, that does not mean being in ketosis is bad for you. It means not eating enough is bad for you.
Similar to measuring if you’re in ketosis, are you guessing or testing with food intake? Are you measuring and tracking your food intake? Use an app like MyFitnessPal to track your food. When I recorded food for my ketosis experiment, I typically was always surprised that I was under eating. I wouldn’t have known this if I didn’t track.
Yes, it is a pain in the ass to measure everything, but again if you’re guessing don’t complain about your results. You’ll learn soon what your target amount is per day, and what 30g fat and 20g protein looks like together, for instance. If you need, use any bro macro calorie counter to determine what a “maintenance” calorie load should be. This is a good one for a ketogenic diet. As tempting as it may be, do not try to calorie restrict on a ketogenic diet.
You don’t have to worry about calorie restriction if you’re trying to lose fat on a ketogenic diet. You can actually eat more food while in ketosis and still lose the same amount of fat loss as people who calorie restrict. The rate of metabolism and energy regulation is much higher on a ketogenic diet. This means you can eat the same amount as a maintenance diet and still lose fat as if you were on a calorie restricted diet, without the hormonal problems of course. (32)
If you’re on a ketogenic diet and chronically calorie restriction, yes, this may lead to hormonal problems. This is not a problem with ketosis. This is being in a chronic starvation state and pissing your body off. It down regulates certain hormones and then you have hormone problems.
Associated with this problem, but way too much of a topic on its own to address in this post is food quality. Don’t be a fool and take a macro approach to eating on a ketogenic diet. Eat real foods that contain micronutrients. You know, foods that grow and then spoil if you don’t eat them. Don’t be overfed and undernourished. Eat real food.
How to fix this problem: Make sure you’re eating enough high-quality food. Calculate a rough amount of how much you should be eating and track your food intake with an app like MyFitnessPal.
Problem With Ketosis and Hormones #3: You’re Overtraining
Let me state this again, very clearly: A ketogenic diet is not perfect for everyone.
If you’re trying to do high-intensity exercise 3+ times per week with performance as your priority, and you eat a ketogenic diet and start experiencing symptoms of overtraining, yes, this may lead to hormonal problems. This is not the fault of ketosis, it is of applying the wrong tool to the wrong job.
Overtraining is certainly a phenomenon that is not fun and certainly messes with hormones. This includes decreasing female reproductive organs, modulating of the thyroid gland, and increased cortisol The symptoms of overtraining may include weakness, fatigue, low energy, amenorrhea, and low mood. (33) (34) (35) This sounds a whole lot like what people about why ketosis is so evil. Hmm.
As always with anything you do in life, you need to ask yourself if you’re using the right tool for the right job. Ketosis is a tool. I would say ketosis is not a great tool for supporting the fuel for sustained high-intensity training. To know the tool you need to use, you need to know the job you’re trying to get done. If I tried to use a hammer to screw something together or to saw apart wood, and I bashed everything to bits, I wouldn’t complain about the hammer, I’d complain about being an idiot. Hint: you can’t have it all.
What are your priorities? If you had to rank them in a top five list, where do they lie? There is nothing magical about ketosis that makes it a nutritional approach that everyone needs to adopt. You need to be honest with yourself and address your goals from one to five. Start with the most important priority to you and focus on that. Don’t be silly enough to think that you can have your cake and be keto too.
If your goal is high energy, low inflammation, longer lifespan, mental clarity, weight loss, ease of fasting, prevention of cancer and neurodegenerative diseases, and increase in mitochondrial health a ketogenic diet may be for you.
If your goal is to gain muscle mass, pregnancy, or high-intensity athletic performance, a ketogenic diet is probably not for you. The demands on certain energy systems with a super explosive workout regiment do not pair well with a ketogenic diet.
There are some discussions now that argue if given long enough, anyone can become fat adapted for any goal. There is an argument that these adaptations can take up to two years, but the athletes need to take time to increase their training and resist the temptation to overtrain at the outset of switching to a ketogenic diet. I don’t recommend it because the verdict is still far from conclusive.
If you still want to do high-intensity exercise and remain on a ketogenic diet, just ratchet it down a bit and don’t push the same as if you were eating carbs. You might also want to think about using exogenous ketones, especially when transitioning to ketosis and while you are working out, as your body won’t have a lot of readily available energy. Eating “lowish” carb, not being in full nutritional ketosis and just adding in exogenous ketones aren’t going to save you though. Exogenous ketones will make hard workouts easier, but they don’t create some magical middle road where you can eat a shitty non-ketogenic diet and think you’re in ketosis just because you have temporarily elevated ketone levels.
Again, what are your priorities? Let your ego float a little bit and don’t be so concerned if your PR drops by 5% if that means you are healthier overall. Don’t train so crazy if you’re switching to a ketogenic diet, especially at the beginning.
How to fix this problem: Align your nutritional choices with your goals. If high-intensity performance is number one, don’t do a ketogenic diet. If you’re having energy or hormone problems on a ketogenic diet, stop training so damn hard.
Problem With Ketosis and Hormones #4: You need to address your stress levels
Making a dietary change, especially shifting your metabolism from using one fuel to another, can certainly be a stress to your body. However, this stress in a normal situation should be easily dealt with. If you poured a little bit of gasoline on a blazing fire and it made things worse, you wouldn’t be surprised, would you? If you, like most Americans, have a problem with being overstressed, this indeed can lead to a cascade of hormonal problems.
An over secretion of stress hormones is not the fault of ketones, ketosis, or eating a ketogenic diet. It is a result of being over stressed. Duh. Ketosis can probably exacerbate a stress mediated hormonal problem, but it doesn’t cause it. The same response would happen if you went from keto to high carb, too.
Stress is one of the four pillars of health and should be addressed in conjunction with nutrition, movement, and sleep to optimize health. If you have constant anxiety and are chronically stressed, this can lead to many more measurable health problems than a ketogenic diet. (36) Studies have shown that stress can lead to hormonal problems, especially in females, and reducing stress can help to remedy these problems. (37)
Stress must be addressed and ruled out as a contributing factor before you can claim that a ketogenic diet led to hormonal problems. If you are experiencing any symptoms of stress, doing more light movement (like yoga), practicing meditation, getting more sleep, being outside more and journaling can all help reduce levels of stress.
Sometimes stress induced hormonal changes may be cyclical and require medical intervention. In these cases, working with a functional medicine clinician to run something like a DUTCH test would be beneficial.
How to Fix This Problem: If you have symptoms of chronic stress, try stress reducing techniques. My favorites are walking in the woods and meditation (use Headspace for a jump start). If you feel like things are really awful, go get a DUTCH test from a functional medicine clinician.
Summary Of How Ketosis Impacts Hormones
As seen above, the two main reasons why people think ketosis is bad for hormones, that it disrupts your HPA axis and ruins your thyroid, are both mistaken and not true.
The main problems that people who anecdotally claim ketosis is responsible for are actually not being in a ketogenic state, chronically calorie restricting, overtraining, or being overstressed — or a combination of the listed.
People try to have it all. They try to calorie restrict to lose weight, they try to burn through physical performance all while not really doing the work and measuring to see if they are using the right substrate or not.
It’s not uncommon to see someone who is trying to do something like CrossFit switch to a ketogenic diet but not actually measure to see if they are in ketosis, try to restrict calories to lose fat and eat a low quality diet because they’re on some silly macro plan, while working out even harder to lose more fat, and being stressed out that their numbers in the gym are dropping and they aren’t losing fat. They start having energy and fatigue problems. Chaos ensues.
This doesn’t sound like a problem with a ketogenic diet to me, it sounds like a mismanagement of overall health.
Not only do the “keto causes hormonal problems” claims spread misinformation, I actually think they can be damaging to females who would otherwise benefit highly from them. Polycystic ovarian syndrome (PCOS), uterine fibroids, and endometriosis all can benefit from a ketogenic diet. (38) Not to mention, effortless fat loss, reduction in inflammation, normalization of hypercholesterolemia, treatment of type II diabetes, neurological disease, cancer, and insulin resistance and overall just feeling great.
Disclaimer: A caveat to this article is that this applies to healthy adult women. As mentioned before, humans that are growing and going through puberty shouldn’t be doing long term ketosis without it being used as a therapy for certain conditions. The general rule of thumb is when you want growth, you want some (whole food) carbs. This also applies to pregnant women. Keep this in mind and be very clear that I am NOT recommending ketosis for adolescent women or pregnant women.
Ketosis is also just not for everyone. If you try it out and you remove any potential problems above and you still don’t feel amazing, that’s fine. Different people have different goals, different metabolic history, different genetics and different results from different applications of nutrition. That’s totally normal.
I just ask you don’t do this keto thing half-assed then write hate mail or public comments online that prevent other people from actually enjoying it.
If you read this and have a reasonable biologically mechanistic argument backed up by literature as to why measurable ketosis (and not just general “low carb” diets, under eating, or over training) contribute to hormonal issues in women, please comment below or send me an email.
I’m genuinely open to new information and changing my mind and will update this article if I come across any compelling data.