There's a lot of debate surrounding low-carb diets and whether they are helpful or harmful. As low-carb diets have become increasingly popular, it's an important question to ask.
Low-carb diets are often touted as a tool to kick start weight loss or balance blood sugar. It's true that some people benefit from restricting carbs, but low-carb diets aren't always the answer to long-term health, and for a lot of women, cutting out carbs can negatively impact hormone balance. Like anything else with health, your response to restricting carbs depends on your bio-individuality.
I've seen both sides firsthand and I spent a lot of time diving into the research. In this article, I'll share what the science says about low-carb diets and women's hormones and what I've seen in practice with women who follow low-carb diets so that you can make the best choice for your body.
What is a Low-Carb Diet?
Most of you reading this right now have at least some idea of what a low-carb diet entails. A low-carb diet is an eating pattern that limits carb-containing foods, but there are a few nuances to keep in mind.
There's no single definition of a low-carb diet, so the actual amounts of carbs you include can vary. Since the diet focuses on eating fewer carbs than you would on a standard diet, it usually means cutting out foods like bread, pasta, rice, and potatoes.
Depending on the type of diet, you may also dial back your grains, legumes, lentils, or even fruit. Low-carb diets also tend to be higher in protein and fat to compensate for the calories that you would have otherwise consumed from carbs.
Low-carb diets can vary, depending on what kind of program you’re following. Some people follow very low carb diets like the ketogenic diet, which can mean eating less than 20 grams of carbs per day on the strictest end. More commonly, people will allow themselves up to 50 grams of carbs per day to allow for some flexibility. Then, you have moderately low-carb diets coming in under 100 – 150 grams of carbohydrates per day, which leaves some wiggle room for several servings of fruit or vegetable-based carbohydrates each day. Even a moderately low-carb diet still stays well under what you would eat on a Standard American Diet.
Hormonal Side Effects of a Low Carb Diet for Women
Following a low-carb diet short-term could have benefits, but long-term, there may be some side effects that are worth considering. Women's bodies are especially sensitive to changes in their diet and energy intake, so it's essential to be aware of how a low-carb diet may affect you.
It's also worth mentioning that many of these side effects are due to severely restricting carbohydrates. Moderate restriction, or just cutting back on refined and processed carbs, is different and unlikely to have the same impact (and we will explore this below).
Low-carb Diets Can Affect Women's Adrenal Function and Hormones
The phrase adrenal fatigue is thrown around to describe a constellation of symptoms that show up as symptoms of major burnout—exhaustion, irritability, anxiety, or chronically feeling completely wired but unable to rest.
But it's not exactly the correct term. Your adrenals, the small glands that sit on top of your kidneys that help you manage stress, can't really get tired, but they can become overactivated.
Instead, it's more accurate to call so-called adrenal fatigue as Hypothalamic-Pituitary-Adrenal (HPA) axis dysregulation, although I know this isn't quite as easy to say. The HPA axis is a complex system between your brain and adrenals that regulates your stress response.
When we experience stress, the HPA axis kicks into gear, releasing cortisol and other hormones to help us deal with the stress. This is a normal, healthy response that helps us cope with short-term stressors.
But when stress becomes chronic, it can disrupt the HPA axis, and you continue to pump out stress hormones without giving your body a chance to break them down, so you feel totally exhausted and burnt out.
How is this connected to diet? Undernutrition, or not eating enough, is considered a stressor, especially for women's bodies. If a woman cuts carbs too low over time, it can disrupt or add to existing stressors that throw off the HPA axis, causing the symptoms associated with adrenal fatigue or HPA axis dysregulation.
For someone who already has a lot of stress in her life, going low-carb could be a problem because it could make things worse. One study showed that going low-carb increased the release of cortisol.
Low Carb Diets Can Affect Sex Hormones
When you restrict your food intake, your body turns down the production of certain sex hormones as a protective mechanism. Think about it—if you’re not eating, your body gets the signal that there’s not enough food in your environment to sustain a pregnancy. So, your body will dial back the hormones that help make pregnancy happen.
Under nutrient scarcity, the hypothalamus can turn down the production of these essential sex hormones, which in turn can affect your period and fertility, as I'll discuss in a moment. But hormone imbalances can lead to symptoms beyond changes in your menstrual cycle, affecting mood, libido, energy, and more.
Your hypothalamus (yes, the same one that's part of the HPA axis) is responsible for ensuring you have the hormones needed for a healthy menstrual cycle, and it's wary of stress.
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Low Carb Diets Could Impact Your Thyroid
Low-carb diets can sometimes lead to disruptions with the thyroid because carbs are needed to convert thyroid hormone into the active form.
The thyroid is a gland in the neck that helps control how your body uses energy. It produces essential hormones that regulate metabolism, but some research suggests that going too low carb could induce hypothyroidism which means your thyroid isn't working as efficiently as it should.
Hypothyroidism can cause problems like weight gain, feeling tired all the time, and difficulty concentrating. Some studies suggest that lower-carb diets could support a healthy thyroid and reduce thyroid antibodies. Still, as mentioned above, others have found that low-carb diets can actually lead to problems with the thyroid, so this may be an individual call.
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Can a Low-Carb Diet Affect Your Period?
Since going low-carb can throw off your sex hormones, it can disrupt your menstrual cycle. In some cases, low-carb diets can even stop periods altogether (called amenorrhea). In the past, amenorrhea was linked to athletes or people who overly restricted calories, but it can happen with low-carb diets for the same reason.
Your brilliant body recognizes that being undernourished and overly stressed probably isn't the best environment for growing a baby, so it can turn off ovulation. As a result, you likely won't get a period. Even if you don't have plans to become pregnant, not getting a period or not ovulating is a sign that your body is under too much stress, and something needs to change.
Will this happen to every woman who goes low-carb? No. There's really not much research on the subject, but I've seen it happen to women. Anytime your cycle changes, it's worth paying attention to the hints your body is trying to give you.
Does Low-Carb Affect Fertility?
As you just read, for some people going too low carb for too long could impact fertility. Alterations in sex hormones can lead to problems with ovulation and irregular periods. This is one of the reasons why most experts won't recommend super low-carb diets for women trying to get pregnant.
A review article examining the impact of low carb diets on fertility for women in larger bodies noted improved hormone balance that could support fertility, especially for those with PCOS. However, the authors mention in the conclusion that it's unclear how long a person should follow a low-carb diet.
A few interesting studies on fertility and carbohydrates point to the importance of the type of carbs a person eats. Some research suggests that women who eat more servings of high glycemic carbs (those that quickly raise blood sugar) have a 14 percent lower chance of becoming pregnant than those who eat the smallest amount.
In the same study, women who ate more fiber—at least 25 grams a day—became pregnant more quickly and had a 13 percent higher chance of getting pregnant compared to those with lower fiber intakes.
So when it comes to fertility, it looks like focusing on nutrient-dense, high-fiber carbs and reducing your intake of refined carbs is the way to go, instead of throwing all carbs out.
How Many Carbs Should Women Eat?
I wish I could give you an exact number to work with, but the truth is nutrition is individual and depends on your body. Body size, activity level, age, stress level, health history, genetics, and sleep patterns could change how many carbs you need.
Generally speaking, most people do well eating somewhere between 45 to 55 percent of their total calories from carbs. Eating lower than 45 percent could benefit some, but it really depends. If you are trying to get pregnant, experience a lot of stress, have any cycle irregularities, feel lethargic and as though you’re not performing optimally or have a history of eating disorders among several other factors, I'd recommend sticking to this range.
If you’re low-carb curious but not sure how your body will respond, some women may also consider carb cycling, where they choose one or two days a week to go lower carb and then eat a standard range the rest of the week. You can try this and see if it feels good for you, as it could be a good way to get some of the health benefits of low carb without overly stressing your body.
Some Women May Benefit From a Low Carb Diet
We can't discuss low carb without sharing some of the benefits. There are absolutely reasons low-carb diets are so popular. Some of the short term benefits include:
- Improved blood lipids
- Better blood sugar control (at least in the short term, new research reveals that long term low carb can actually increase insulin resistance by impairing the liver as well as the beta cells in the pancreas)
- Reduced inflammation and associated pain when the type of carbs restricted are sugary refined carbs
- Weight loss
The important question, aside from the possible impact on hormones, is whether a low-carb diet is sustainable to provide long-term health changes, and the jury is still out on this one. Most studies comparing low-carb to other patterns of eating find no difference long-term.
Low carb diet for PCOS
Since PCOS is rooted in insulin resistance, low-carb diets could be helpful for blood sugar balance. Reducing carbs can help to lower insulin levels, which can improve PCOS symptoms and make it easier to manage weight.
But again, going lower carb is different than low carb. People with PCOS don't need to follow a super restrictive low-carb diet like keto to see benefits. Instead, moderately low-carb diets seem to be the sweet spot for people with PCOS, again focusing on removing highly refined carbs and swapping for high-fiber options.
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Key Takeaways: Lower-Carb Might be Better Than Low-Carb for Women's Hormones
- Remember, a jelly bean is a different kind of carb than a black bean. While both are carbohydrates, one is clearly more nutrient-dense and hormone friendly than the other!
- If you don’t want to drastically slash carbs, another option is to be intentional about consuming quality carbs. You can start replacing low-fiber refined carbs with vegetables, legumes, berries, and other high-fiber foods to see if that moves you in the right direction.
- Whatever route you take, be mindful of how your body reacts to different amounts of carbs. Pay close attention to what your carb counts do to your sleep, your energy levels, and your menstrual cycles. Going too low-carb, such as with keto, could lead to changes in thyroid, sex, and stress hormones that could affect your cycle, fertility, and overall health.
- Low-carb diets do have some benefits, but women especially should pay close attention to how changes in eating pattern impacts hormone balance.
- If you're considering a low-carb diet, it's essential to be aware of potential side effects and take steps to minimize stress on your body. While you’re making changes, getting enough sleep, managing stress levels, and not over-exercising can help you stay level.
- Keep in mind that a deprivation mindset can lead to feeling hungry and miserable all the time, on top symptoms from hormone shifts you may experience. So, before attempting any diet that excludes important nutrients, look for guidance from a qualified professional. You can feel full and satisfied and maintain healthy hormone levels while working toward your goals.
Whatever you do, as always, make your choice from a place of empowerment and self-care, not from a place of desperation. You deserve to eat well and be nourished. You’re worth that and much more!
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