The ketogenic diet has gotten really popular. But what exactly is this diet and who should not do keto? Be sure to read this article before going keto so you are aware of the potential risks to your health.

notebook on a table that says keto diet on the cover.

A ketogenic diet has been all the rage for the last few years, but it’s not right for everyone. There are some definite risks in going keto which you should be aware of before trying it.

This article shares some of the potential dangers of a ketogenic diet, and which groups of people should avoid ketosis, including pregnant women, people with eating disorders, people who are hypothyroid, people with gallbladder disease, children, and high performance athletes.

The information in this article includes information from research articles, but there are no definitive studies on a large scale that show the safety of a ketogenic diet for most people.

What is a Keto Diet?

The goal of a ketogenic diet is to eat a lot of fat so that your body becomes adapted to burning it for fuel. For most people following a keto diet, the aim is to consume approximately 60-80% of daily calories from fat, 15% from protein, and less than 10% from carbohydrates. This is a high-fat diet that may not be a good idea for many people.

The premise of a keto diet is that if you fuel your body with mostly fat (and ketone bodies) while restricting carbohydrate intake, you’ll potentially lose weight, regulate insulin levels, and lower inflammatory markers within your body.

If you are restricting carbohydrates, then your body produces ketones from fat during a process called ketosis. The purpose of producing ketones is to provide energy to the body as an alternative to glucose from carbohydrates.

This is a low-carb diet taken to the most extreme, often limiting ones daily intake of carbohydrates to single-digit figures.

See my related article about What is an Ancestral Diet?

graph showing the breakdown of carbs, protein, and fat on a keto diet.

Who Should Not Go Keto

If you’re seriously considering trying a keto diet, then you really should discuss it first with a licensed healthcare provider who can help determine if it is right for you.

A dietitian or other type of healthcare provider can also help develop a plan to make sure that whatever diet you try is safe and meets your overall nutritional needs.

That said, there is some research, anecdotal evidence, and agreement on certain groups of people who should not try a keto diet, and who may experience health risks or negative outcomes on a ketogenic diet.

1. People with eating disorders

People who have an active eating disorder or a history of disordered eating patterns should be very cautious when considering a restrictive diet like keto.

The risk of going on a keto diet to people in this group is that the strict rules will trigger the unhealthy patterns again. This can have an overall negative effect on health over the short term and the long term.

woman in a kitchen holding a red bell pepper and reading a recipe.

In fact, there is some research that shows that people with a history of eating disorders or in orthorexia recovery may do better using a non-diet approach.

Therefore, since a ketogenic diet is a highly restrictive diet, anyone who has a history of disordered eating behavior should not consider this way of eating unless prescribed by a doctor and carefully supervised by a professional.

In the same vein, there are also problems with a plant-based diet.

2. Pregnant women 

Because a ketogenic diet only contains around 15% of calories from protein, it may not be right for women who are pregnant.

pregnant woman sitting on a bed holding an ultrasound photo.

It’s recommended that a woman who is pregnant get at least 20% of her calories from protein. The protein requirements for pregnancy then increase up to 25% during the third trimester of pregnancy when the fetus is rapidly growing. See my list of the best protein powders for pregnancy.

Because a keto diet is higher in fat and lower in the other macronutrients than a normal diet, this may signal food scarcity for the body. For pregnancy, this is not ideal since overall nutrient needs are quite high to nourish both the mother and fetus.

Women who are trying to conceive should also be wary about going keto unless advised by a healthcare professional. Learn more about the best diet for fertility. You might also want to read this article on the dangers of intermittent fasting for women.

3. People with adrenal fatigue 

While adrenal fatigue is not considered to be a diagnosable condition by most doctors, there are some people who receive this diagnosis from their healthcare providers.

tired woman holding her hands over her eyes.

When someone is thought to have adrenal fatigue or adrenal burnout, then this means that the adrenal glands are not producing hormones in the right levels or at the right times throughout the day.

While I could not find any research studying the effects of a keto diet on cortisol levels, there is research showing that low-carb diets can negatively affect cortisol levels. More research is needed to determine whether or not a keto diet is appropriate for people with symptoms of adrenal fatigue.

You may also want to check out my article with resources if you feel tired all the time.

4. People with hypothyroidism 

Insulin is needed to convert the inactive thyroid hormone T4 into the active hormone T3.

People on a ketogenic diet generally restrict carbohydrates to the point where not enough insulin is available for this process.

sign that says thyroid disease on it with a stethoscope.

Some people with hypothyroidism who adopt a keto diet report that their hypothyroid symptoms get worse following this way of eating. At least one study indicated that a ketogenic diet can cause thyroid malfunctions in some people.

See my related article on the worst foods for Hashimoto’s.

In this case, a grain-free diet might be more helpful than a low-carb or ketogenic diet.

5. People with no gallbladder 

If you have had your gallbladder removed, you may want to think twice about starting a ketogenic diet.

The risk of going keto when you have gallbladder disease is due to the amount of fat you will need to consume.

woman with gallbladder disease holding her abdomen.

If you have no gallbladder or you have gallbladder disease, you may not have enough bile to break down the fats. The danger in this situation is that you may become malnourished or experience unpleasant symptoms as your gallbladder struggles.

The general diet recommendations for people who have no gallbladder or who have gallbladder disease leans more toward a low-fat diet.

6. People with a history of gut dysbiosis 

A ketogenic diet has been shown to alter gut flora. Those with a history of gut or digestive issues need to be careful when following a ketogenic diet. The danger to this group of people is that a very low-carb diet will reduce the diversity of the gut microbiota.

One of the main issues with a keto diet and a maintaining a healthy gut environment is that our bodies need prebiotics. Prebiotics feed the healthy bacteria in our intestines.

The concern around very low-carb diets is that there is not enough fiber from carbohydrate sources to feed the gut bacteria.

Learn more about natural probiotic food sources, the best gut healing foods, and how to eat a low-histamine diet.

7. Children and teens 

Children and teens are still growing and developing and need a balanced diet.

Unless a keto diet is prescribed by a healthcare provider and is monitored closely, it may cause nutritional deficiencies.

Read more about a keto diet for kids, including when it may be appropriate.

young child in glasses eating lunch.

When it comes to adolescents on keto, the main concern is for females who may experience changes in their menstrual cycle. See my article on how to eat during your menstrual cycle. There is also a risk of delayed puberty on a very low-carb diet.

Again, since there is no definitive research on children or adolescents and the safety of keto diets, it’s best to consult directly with your healthcare provider, and to keep close tabs on any young person who is on this type of diet.

8. High performance athletes

A ketogenic diet may be challenging if you’re a competitive or high-performance athlete since higher activity levels require more calories and quick fuel that often come from carbohydrate sources.

female athlete sprinting on a beach.

There is some research that shows that athletes who adopt a ketogenic diet may have issues. On the contrary, there is much more research showing that higher-carbohydrate diets are best for athletes.

Other Groups

There are other groups of people who may not do well on a ketogenic diet. These include people with a history of kidney disease or people with kidney stones. People with liver disease may also need to avoid keto diet plans to avoid adverse effects.

There may be other health conditions that won’t work well with this high fat diet.

What Does the Research Say?

Of course, a ketogenic diet can benefit certain groups of people. Traditionally, a ketogenic diet has been used in the treatment of epilepsy in both children and adults to control epileptic conditions.

People with type 2 diabetes have shown improvement in biomarkers as well when placed on a well-managed ketogenic diet. They may see reduced insulin resistance (improved insulin sensitivity) and better control over blood sugar levels.

One study showed that adults with type II diabetes that followed a ketogenic diet for 12 months lost more weight and were more likely to not need medications compared to a similar group of people following a moderate-carbohydrate diet.

But, if weight loss is your goal, then you may not have to go as far as a state of ketosis to achieve results. Just consuming fewer carbs (especially refined carbs) can be effective.

The bottom line is that there is no one right diet for everyone. But, what works well for someone may not work well for you. Know your body and know what you can and cannot handle. You might also fare better on a lower-carb diet than a ketogenic diet.


If you fit into one of the above categories of people that may not benefit from a ketogenic diet, then it’s wise to think twice before adopting this lifestyle. Just because everyone seems to be adopting a ketogenic diet does not mean that you have to do it as well.

You might also be interested in this article where I explain the differences between paleo, keto, vegan, clean eating, and Whole30 diets. You might also want to check out my article with the dangers of intermittent fasting for women.

Additional References

Don’t forget to join my newsletter list to get exclusive clean eating recipes and tips. The newsletter is 100% free with no spam; unsubscribe anytime.

About the Author: Carrie Forrest has a master’s degree in public health with a specialty in nutrition. She is a top wellness and food blogger with nearly 10 million annual visitors to her site. Carrie has an incredible story of recovery from chronic illness and is passionate about helping other women transform their health. Send Carrie a message through her contact form.

Note: this post is for informational purposes only and is not intended as medical advice. Please consult your healthcare provider for recommendations related to your individual situation.