Keto had gotten a lot of attention in the past few years. But a frequently asked question is: Is keto bad for hormones? Everyone’s body is different, which makes a blanket answer difficult. But, for many women, the carb-cutting and high-fat foods associated with keto can upset hormone balance and cause issues.
I feel great on keto. How can it possibly be bad for me?
After the first few days, it’s common to hear someone on keto say that they’re feeling better than ever. You’re energetic. Have a clear head. Less bloat. Barely miss carbs. The extra fats are even keeping you full and satisfied. Plus, the pounds are melting away. So why can’t you just do this forever?
But the thing is: even if you don’t feel like you’re missing carbohydrates, most people’s bodies eventually do miss them. Women need several key things to keep hormones balanced, and dramatic changes in any one of these can lead to imbalances. At a minimum, these are:
- stress management to cope with physical, emotional, and environmental stressors and limit adrenaline and cortisol
- enough calories
- good energy sources of all three macronutrients (protein, healthy fats, and carbohydrates)
- a variety of foods to gain a wide range of micronutrients
- slow, steady changes to body composition
- reduced exposure to xenoestrogens found in the environment
Keto can easily disrupt any (or all!) of these. To your body, drastically cutting carb consumption can be stressful and make you release more cortisol, which affects your insulin balance, progesterone levels, and more.
What else? The sudden, new numbers on the scale during keto definitely feels welcome and like a win. But a lot of women’s hormones have a hard time with rapid weight loss. Quick changes in body composition reduces the amount of gonadatropin hormone (GnRH) you release. That ultimately leads to missed periods and low progesterone. Other women might find themselves with too much estrogen as a result of dietary choices. Estrogen dominance has a wide range of symptoms, makes for heavy and frequent periods, raises your risk for cancer and is all-around uncomfortable.
How keto can be behind hormone changes that lead to period problems
Keto diets can be bad for hormones in several different ways. One is how it can affect your menstrual cycle. Some women might find that their period becomes shorter or irregular–or you skip it all together. In other instances, it can lead to heavy periods, fibrocystic breasts, and more symptoms.
When you skip your period on keto or it’s lighter and irregular
That reduction of GnRH we mentioned earlier? Low levels mean you might not make enough luteinizing hormone (LH) or follicle-stimulating hormone (FSH). These two hormones help guide the orchestration of sex hormone levels throughout your menstrual cycle. Without enough, you might not ovulate or get your period.
Why is that such a problem? Unless you’re in menopause, your cycle is a good indicator of what’s going on in your body and a helpful measure of your health. When you ovulate, progesterone is released into your bloodstream. Progesterone is important to your cycle, but it also has a lot of other functions. If you’re not ovulating, you might experience symptoms of low progesterone: insomnia, anxiety, inability to relax, migraines, and more.
When your period gets heavier and more frequent
For some women, hormone changes can mean heavier periods that are spaced closer together than normal. It’s possible that this happens from high levels of estrogen or estrogen that’s high compared to your progesterone. (Those two hormones counteract each other.)
Having estrogen dominance isn’t that uncommon as it is. The reason: progesterone starts to drop in your mid-30s. Estrogen dominance can cause symptoms such as:
- Weight gain
- Swollen or tender breasts
- Fibrocystic breasts
- Frequent or heavy periods
- Low energy
- Worsening PMS
- Trouble remembering things
- Changes in mood or outlook
- Water retention/bloating
- Low sex drive
- Higher risk of certain cancers
Estrogen dominance happens for a variety of reasons. It can be a result of an inability to detox estrogen through your digestive tract or chronic constipation (common in keto). Another way it can occur is from chemicals that disrupt the endocrine system. Many environmental factors, beauty care products, and foods have chemicals called xenoestrogens. Xenoestrogens act like a weak estrogen in your body and can disrupt your hormone balance–and going keto might mean you’re getting more of them.
One way keto can lead to increased intake of xenoestrogens
Exposure to xenoestrogens is already a potentially problematic situation for many women. Keto’s hefty fat requirements (70% of caloric intake) make some people rely heavily on fatty or skin-on meats and full-fat conventional dairy products, like heavy cream. It’s common for natural and synthetic estrogen (and other hormones) to get used to make animals fatter or increase their milk supply and production. Those hormones get passed along in our food supply. Eating more meats and dairy mean you might be getting more of those hormones on a regular basis.
Keto can increase your intake of dioxins, which are bad for your hormones
Dioxins are another issue for hormone imbalance, and a keto diet can increase your intake if you’re not careful. Dioxins are toxic chemicals that exist in our environment—mostly in soil. (They’re actually an unintentional byproduct of manufacturing.) In 1979, the U.S. government put a ban on PCBs, including some dioxins. But dioxins still belong on your worry list. With two benzene rings joined by a pair of oxygen atoms, dioxins very stable. Unfortunately, that means they stick around for a while. Dioxin levels take 15 years to reduce by half in topsoil alone. Deeper layers of soil hold onto dioxins far longer.
So how does that affect us? Consider this: top layers of soil are where the animals making up our food supply graze and where feed comes from. Dioxins become absorbed by these animals and get stored mainly in their fat tissue. When we consume fatty types of conventional meat or dairy, we inadvertently get dioxins too. This can even happen with organic meats, too. According to the National Institute of Health, more than 90% of our dioxin exposure comes through the food we eat.
One problem with this is that many dioxins are estrogenic. They also upset normal cell function. Dioxins activate a part of your body called the aryl hydrocarbon receptor (AhR). Once turned on, this receptor recruits another receptor, the aryl hydrocarbon nuclear translocator (Arnt). This sets genetic changes into motion, creating a chain reaction of possible health issues. Some of the conditions associated with dioxins? Cancer, developmental issues, immune dysfunction, infertility, and hormone imbalance.
But does our diet really affect the amount of dioxins we take in?
In 2001—twenty-one years after the ban on PCBs—a study took individuals on different types of diets and tested for dioxin levels. The individuals with the lowest levels of dioxins followed a vegan diet. (Think: no meat, eggs, or dairy.) Which raises two important points: 1. regardless of what you’re eating, there’s a side-helping of dioxins, and 2. people who eat animal products are probably getting more dioxins than those who don’t.
It also raises concerns about high-fat diets like keto and how we get those fats—especially when we do this over a long time span. If vegans have the lowest dioxin load of all dietary preferences, it stands to reason: full-fat or higher-fat conventional animal products might pass along more dioxins than lower-fat alternatives. In fact, the National Institute of Health offers this advice to reduce your dioxin exposure: choose leaner cuts of meat and low-fat dairy. Is it possible to do keto and limit your dioxin exposure? Yes. But how many of us really do that on keto?
Is keto bad for any other hormones?
So far, we’ve mentioned the effects of stress hormones, low progesterone, and high estrogen (or an imbalance of estrogen to progesterone). Imbalances in these hormones have wide-reaching effects because progesterone and estrogen aren’t just important to fertility. They affect your cardiovascular system, bone health, brain function, and so many other functions in your body.
On keto, some women’s thyroid hormones suffer. Thyroid hormones are needed by every cell in your body and effect your energy and metabolism. Usually, when you lose weight, your body naturally reduces the amount of thyroid hormone it produces. This is a built-in protection mechanism. Because keto switches your body into ketosis, your body thinks it’s in a metabolic state of starvation.
During periods where your body thinks it’s starving or restricting carbs, both main types of thyroid hormones, triiodothyronine (T3) and thyroxine (T4), decrease. Estrogen and progesterone imbalances also affect the thyroid. So do micronutrient deficiencies, which easily can happen if you’ve restricted certain foods.
Are these changes significant? That’s individual. But they can be enough to cause hypothyroidism in some people. Women with Hashimoto’s hypothyroidism who would like to go keto should absolutely not begin without talking to a healthcare provider knowledgeable in thyroid health.
The bottomline on if keto is bad for hormones
As unpopular as our opinion is, we feel keto can be bad for some women’s hormones. It leads to imbalances in a number of hormones, whether from xenoestrogens or micronutrient deficiency or other causes. Is it also good for some people? Yes–its positive effects have been widely noted, from seizure reduction to the possibility of clearer skin, reduced inflammation, lowering risks for certain diseases. But like anything else, whether or not it’s for you deserves careful consideration and a chat with your physician or nurse practitioner. It’s also a good idea to chat about if you should consume more carbs and less fat than a traditional keto diet calls for in order to encourage weight loss but avoid some of the unwanted effects.