Are Ketogenic Diets Harmful for Women?

Ketogenic diets that focus on anti-inflammatory, fiber-rich foods and healthy fats can work exceptionally well for fat loss, energy, brain health, metabolic health and upgrading your overall health but they do not work well for everyone. As simple as ketogenic diets might seem, there are several things to consider, especially for women who are still menstruating. Due to regular hormonal fluctuations, women are more susceptible to complex results when adopting a ketogenic diet. 

Clinically, ketogenic diets are often used for Type 1 and 2 Diabetes, pre-diabetes, metabolic syndrome, PCOS, hyperinsulinemia, non-alcoholic fatty liver disease, intractable epilepsy, narcolepsy, parkinson’s disease, alzheimer’s disease, migraines, cancer, and more. A lot of people have experienced life changing transformations from adopting a ketogenic diet but at the same time, many people, especially women have experienced a worsening in their health. Before diving into a ketogenic diet, you will want to identify the best approach for you personally. I’d highly encourage you to work with a practitioner in order to get clear on your health state, health goals and whether this is the right approach. 

My Personal Story with Eating Ketogenic 

I personally found out the hard way that a ketogenic diet does not work well for everyone. A deep state of ketosis has the ability to create too much stress and tax your adrenals! In 2018 I shared my first experience of adhering to a ketogenic diet on Mindbodygreen. After recommending ketogenic diets and creating a ketogenic diet program for patients with Type 2 Diabetes at the Cleveland Clinic, I wanted to see how keto could help my energy levels. I am always trying to optimize energy since I have narcolepsy. In the first few months, my energy levels and mental clarity were exceptional! My body composition also improved without that being a focus. 

In addition to eating keto, I was also doing intermittent fasting for 16 hours every day with the intention of supporting my energy, drank Bulletproof® coffee in the morning, regularly did high-intensity interval training (HIIT), and was working a high-stress job. With so many stressors at once, it became difficult for my body to maintain a state of homeostasis, as it began to burn out. At the time, the concept of “dosing” stressors” was not on my radar. But it became clear that I incorporated too many stressors into my routine at once.

The symptoms that I began to experience several months later when I continued a modified ketogenic diet were fatigue, low grade anxiousness and heart palpitations in the middle of the day, difficulty sleeping, difficulty exercising and weight gain. I don’t want you to make the same mistakes I did, but I also don’t want to deter you from trying a ketogenic diet. Done correctly, many women can get great results. 

Background on Ketogenic Diets

If you are new to ketogenic diets, they induce a state of nutritional ketosis where the body uses ketones as its primary fuel rather than glycogen. This is a very high fat diet: about 60-70% fat, along with 20-30% protein and 5-10% carbohydrates. Because fat is the primary building block for hormone production, this can be beneficial for some. It typically means reducing your carbohydrate intake to around 30 to 50 grams a day, depending on age, gender and activity. On a ketogenic diet, fat rather than carbohydrate becomes the body’s energy source. Many organs rely on glucose from carbohydrates as their primary energy source. When you keep carbohydrate intake below 50 grams per day, however, the body has almost no incoming glucose, and glycogen (or stored glucose) gets depleted. 

Thankfully, ketones provide an alternative fuel that allows these organs to function. Two processes occur in ketosis:

Gluconeogenesis is when the body – especially the liver – creates glucose from lactic acid, glycerol, and the amino acids alanine and glutamine. When glucose availability drops further, the liver becomes unable to produce enough glucose to supply the body’s energy needs. As a result, ketogenesis provides an alternate energy source as ketones, which replace glucose as the body’s primary energy source. This leads to an increase in circulating levels of ketone bodies in the bloodstream, which are used as an energy source by the central nervous system, in place of glucose. This process also keeps insulin levels low, which is significant for weight loss and those with pre-diabetes or blood sugar imbalances. 

The Role of Estrogen

The ketogenic diet can influence a wide range of hormones. Because most research is conducted first in males, there is not an ample body of science that demonstrates the impact that keto has on women and female hormones. But one of the many hormones that may explain why women do differently than men on ketogenic diets likely involves estrogen. 

One study published last year gave mice a ketogenic diet (with 75 percent fat, three percent carbs, and eight percent protein) or a normal diet (with seven percent fat, 47 percent carbs, and 19 percent protein). Fifteen weeks later, the male mice lost weight, while the female keto mice gained weight. 

Researchers suspected that estrogen was the driving factor. To find out, they removed the ovaries from some of these mice, which then got the same weight-loss effects as  the male mice. Estrogen could impact how females respond to a ketogenic diet. 

While this was an animal study, it provides some insights about how ketogenic diets might impact women differently. Most likely, other hormonal and metabolic factors come into play, and further studies will highlight those variables.

If your estrogen levels run on the high side and you have estrogen dominance (read more about that here) then getting adequate fiber on a ketogenic diet could not be more important since dietary fiber binds excess estrogen that the gut can then eliminate. Adding 2 Tbsp of ground flaxseeds daily is additionally beneficial for their combination of fiber and lignans. Be sure to use most of your carbohydrate sources on fiber rich foods like non-starchy vegetables, nuts, and seeds. Getting enough fiber will also aid in having a daily bowel movement, which is critical for estrogen clearance. 

The Impact on Insulin 

Outside of estrogen, another key hormone that may be positively influenced on a ketogenic diet is insulin. In a healthy body, insulin helps glucose get into cells to provide energy. When glucose levels fall outside of the healthy range, however, the pancreas continues to secrete insulin, although eventually this organ can get burned out. Adding to this problem, cells begin to “resist” the signal of insulin. 

Over time, this can create insulin resistance, which left unchecked can lead to pre-diabetes and eventually type 2 diabetes (T2D). I’ve explored why insulin resistance is an overlooked driver for weight gain and metabolic problems in this article. For females specifically, insulin resistance can manifest as Polycystic Ovary Syndrome (PCOS), a hormonal disorder in women who are of reproductive age. PCOS can lead to adverse symptoms such as irregular periods, androgenic acne and facial hair growth, weight gain and even infertility. A common pharmaceutical drug used for PCOS and T2D is metformin, which helps lower levels of circulating insulin. 

Some people can skip the metformin or decrease their use of the drug by following a low carbohydrate diet that increases insulin sensitivity. A 2017 study that reviewed the effect of low carbohydrate diets on fertility hormones in women who were overweight stated, “there is convincing evidence that reducing carbohydrate load can reduce circulating insulin levels, improve hormonal imbalance and result in a resumption of ovulation to improve pregnancy rates.” 

When following a ketogenic diet, it’s best to work with a practitioner and track your HgA1c, fasting glucose and fasting insulin levels. 

Cortisol & Too Much Stress

When following a ketogenic diet, keeping cortisol levels in check can help prevent anxiety, heart palpitations, fatigue, brain fog, insomnia, decreased conversion of thyroid hormones T4 to T3, and changes in sex hormones. High cortisol levels can lead to an increased production of testosterone and estrogen and lower progesterone. Factors beyond the ketogenic diet that can commonly increase stress and lead to increases in cortisol include: caloric restriction, extended periods of intermittent fasting, over-exercise, and excessive caffeine intake. Another stressor can be too low body fat. 

Restricting calories while restricting carbohydrates is often not necessary and will increase stress on the body. For women that hold onto excess belly fat that is driven by insulin resistance, lowering your carbohydrate intake can often improve insulin and blood glucose levels. If insulin levels stay low and the body has access to stored fat cells, it will help your body burn fat for energy. A Harvard study concluded that there is a possibility that focusing on restricting carbohydrates rather than calories may work better for long-term weight control. 

A common recommendation to further increase ketone levels and enhance weight loss while on a ketogenic diet is to restrict the window of eating time but this can also be a stressor. This usually means an overnight fast of 14-16 hours and eating all meals within a 8-10 hour window. I often do not recommend women incorporate an overnight fast for more than 14 hours while also eating a ketogenic diet because of the way that both approaches impact cortisol levels. 

A third recommendation that is promoted within the ketogenic community is bulletproof coffee which may further increase cortisol levels. Bulletproof coffee was founded by biohacker, Dave Asprey who recommends blending coffee with grass-fed butter and MCT (medium chain triglyceride) oil when fasting. It does not break your fasting window because the fat in the coffee has a minimal impact on blood glucose levels. People often report an increased level of mental clarity when they start the day out with bulletproof coffee. Women particularly need to be cautious of fasting for too long and drinking bulletproof coffee, two things that can further contribute to higher levels of cortisol. 

Keto for Muscle Building in Women

We also have a few human studies looking at keto diets for female athletes. In one, researchers assigned 21 strength-trained women either a ketogenic diet or into a non-ketogenic group. The keto group consumed 30 to 40 grams of carbohydrates with a slightly higher protein intake, whereas the non-keto group consumed a higher-carbohydrate diet. 

Researchers concluded that a ketogenic diet could decrease fat mass and maintain muscle after eight weeks of resistance training in trained-women. However, a ketogenic diet proved to be less than ideal for building muscle.

Another study looked at ketogenic diets among CrossFit®-trained men and women over four weeks. For men, the ability to utilize fat increased during intense exercise to a greater extent than women, showing that in some aspects a ketogenic diet might favor men. Again, the study was small: 11 men and 11 women. 

Carb Cycling with Keto for Women

If keto seems to be a great option then you will want to determine how much carbohydrate restriction is beneficial. Carb cycling is an amazing part of a flexible keto plan that can help balance hormones, prevent adrenal dysfunction and allow more variety into the diet. I recommend carb cycling for my female clients, especially when under high stress, when your body benefits from nutrient-rich carbs like sweet potatoes, quinoa, buckwheat, etc. 

Here are a few ways to approach carb cycling: 

1. Cyclical Ketogenic Diets alternate periods of higher-carbohydrates days with keto days. You might do keto six days and then cycle that with one high-carbohydrate day per week. Think of high carb days as an opportunity to consume more nutrient-dense carbohydrates such as fruit, non-gluten grains like quinoa, larger servings of beans and lentils, etc. This does not mean filling your days with pizza, ice cream and beer. 

2. Cycle Around your Cycle means shifting your carbohydrate intake based on where you are in your monthly cycle to help promote regular menstrual cycles and support hormone levels. The best time to increase your carbohydrate intake is within the first few days of your cycle and during your luteal phase, about five days before your period starts. But it’s important to listen to various cravings that you experience on a week to week basis that may be related to the weekly hormonal fluctuations that happen for menstruating women. 

Alisa Vitti, functional nutritionist and founder of Flo Living recommends incorporating more carbohydrates in the luteal phase, which is the fourth week of your cycle. This would be around days 22-25 of your cycle. Carbohydrate rich foods can include butternut squash, sweet potatoes, quinoa, sprouted brown rice, berries, apples, chickpeas and more. You may also benefit from more carbohydrates during the first few days of your menstrual cycle. The best place to start is tracking your cycle using a fertility tracker like Daysy. And log the times of the month that you experience more carbohydrate cravings. 

3. Targeted Ketogenic Diets allow more carbohydrates around physical exercise. In other words, you would stick with a high-fat, low-carb diet for most of the day and then incorporate more nutrient-dense carbohydrates two hours prior to a workout and within one hour after a workout.

Recommendations for Adopting a Ketogenic Diet 

1. Eat a Diet Rich in Nutrient-Dense Whole Plant Foods

Unfortunately, the idea of gorging on big plates of bacon and butter-soaked steaks still prevails with keto diets. Yet on even the strictest plan, it’s essential to incorporate plenty of nutrient-dense plant foods that contain antioxidants and fiber, such as leafy greens, onions, zucchini, eggplant, pumpkin seeds, chia seeds, and more.

2. Ensure Adequate Fluids and Electrolytes 

Hydration and electrolytes are especially important as your body is adjusting to burning fat as fuel. During that process, you may experience some short-term side effects of ketogenic diet, collectively called the keto flu. They include: 

  • Nausea
  • Vomiting
  • Headache
  • Fatigue
  • Dizziness
  • Insomnia
  • Difficulty exercising
  • Constipation

These symptoms usually resolve in a few days to few weeks and are mitigated with proper hydration and electrolytes. Maintaining proper hydration and getting enough electrolytes is very important on a low carb or ketogenic diet.

3. Address Potential Nutrient Deficiencies 

There are certain nutrients that aid in supporting a healthy menstrual cycle and adrenal support that you can get through food and may also benefit from additional supplementation. These include: 

Omega 3 Fatty Acids 

B Vitamins (especially during the luteal phase, week 4 of your cycle) 

Magnesium Glycinate 

Vitamin C

Supplementing with compounds that help modulate the stress response outside of the nutrients listed above may also be beneficial. Two of my most commonly used recommendations include rhodiola, in addition to L-theanine. 

4. Avoid High Levels of Caloric Deprivation 

This is especially true if you have a healthy percent body fat. You do not need to further restrict calories to see results. 

5. Avoid Prolonged Fasts >14 Hours Overnight 

You may be able to increase this window very gradually, this would be especially true if you do not have high levels of stress, hypothyroidism, or a low to normal body weight. If you do not have a regular cycle, I would not recommend incorporating an overnight fast.

6. Limit Caffeine and Alcohol 

Both caffeine and alcohol act as stressors to the body. Limiting both coffee and alcohol intake will help support your adrenal function. If you are still in need of caffeine, switch to matcha or green tea that provides the calmin l-theanine, in addition to caffeine. 

7. Prioritize Stress Reduction and Sleep

I cannot emphasize enough the importance of prioritizing rest and relaxation, not pushing yourself too hard and listening to your body while you are adjusting to a ketogenic diet. Incorporate breath work, massages, baths, essential oils at night, calming music and other therapeutic agents that can help you find your chill! 

At the end of the day, the best thing that you can do for yourself is listen to your body. If you have tried a ketogenic diet, pay attention to whether you feel better or worse and monitor your labs. The worst thing that you could do is stay on a diet that makes you feel worse or that makes your lab values worse. There is no one size fits all approach to nutrition so listening to your body will always be the most powerful way to stay on the right track, in addition to working with a practitioner!