Keto Flu: Symptoms, Causes & How to Fix it

Medically Reviewed By: Dr. Surajeet Kumar Patra, MBBS, MD, FDIAB, MBA & APMP March 3, 2022

Last updated on July 28th, 2023

Nowadays, many people are going after the ketogenic diet for weight management. Lowering the carb consumption to a minimum might aid in losing a few pounds. That too, in the initial few weeks to months. Any treatment may result in undesirable outcomes. And, the ketogenic diet is no different. One of the most well-exposed complications of ketosis is known as “keto flu.”

What is Keto Flu?

Keto flu is a range of signs that might arise 2-7 days after initiating a ketogenic diet. Some of the common signs include weakness, headache, nausea, irritation, sleeping problems, and constipation. It is hard to explain exactly what takes place after altering one’s diet. As, it completely depends upon individual’s observations and experiences. These signs might not be exceptional to the ketogenic diet. Few patients may notice similar signs after reducing intake of processed foods. While, few may decide to follow an elimination or an anti-inflammatory diet.

Keto flu: Symptoms, Causes & How to Fix it


Keto Flu Causes 

A person’s major energy source is carbohydrate. While on keto diet, individual lowers his or her carb consumption to below 50 grams per day. This can be compared with the advisable value i.e., 200 to 300 grams per day.

When the body fails to consume enough carbs for energy, the liver starts forming sugar, using its stores. This process is known as glucogenesis. Thus, liver won’t be capable of producing enough glucose to maintain the energy demands of the body.

Then, the body begins to break down fatty acids. This results in production of ketone bodies. Process is known as ketogenesis. Body tissues then make use of ketone bodies as fuel. And, the person goes in the state of ketosis.

The deficiency of carbs reduces the amount of insulin in the blood. Consequently, individuals might experience an increase in the quantity of sodium, potassium, and water liberated in the urine. And, this causes dehydration.

Also Read: Normal Blood Sugar Levels

Signs of Keto Flu

Converting to a very low-carbohydrate diet is a drastic change. And, a person’s body might require time to acclimatize to this new way of consuming. For a few individuals, this transition period might be extremely challenging. Symptoms of keto flu might begin cropping up within some days of decreasing carbs. Signs can be mild to severe and may differ from individual to individual. Also, few individuals might change to a ketogenic diet without any side effects. And, other might experience one or more of the following signs:

  • nausea
  • vomiting
  • muscle cramps and pain
  • irritation
  • drowsiness
  • fatigue
  • sugar cravings
  • constipation
  • diarrhoea
  • headache
  • stomach pain
  • poor concentration
  • difficulty sleeping

These signs commonly occur in people who have just started the ketogenic diet. Signs might be upsetting and they typically last about a week. Few individuals might experience them for a longer duration of time.

Also Read: HbA1c Normal Range

What to Do For Keto Flu?

Protecting the body from damage of chronic inflammation can be the first step. Chronic, low-grade inflammation might turn into a silent killer. And, this may add to heart diseases, cancer, type 2 diabetes and other chronic problems. Keto flu may leave a person feeling miserable. Fortunately, there are ways to lower down its flu-like signs. Also, they aid a person’s body go through the transition period more easily.

Stay Hydrated

Drinking a sufficient amount of water maintains optimal health. Also, it might help in lowering down the signs. A keto diet may result in a rapid fall of water stores. Thus, increasing the risk of dehydration. This is due to the reason that glycogen (stored form of carbs) binds to water in the body. With the decrease in the dietary carbs, there is a drop in the levels of glycogen. This increases the water excretion from the body. Hydration helps with signs such as fatigue and muscle cramping. Fluid replacement is particularly important. That too, when a person is experiencing keto-flu-related diarrhoea, which may result in an additional fluid loss.

Replace Electrolytes

Dietary electrolytes replacement helps in lowering the signs of keto-flu. While following a ketogenic diet, insulin levels reduce. Insulin is a vital hormone that helps the body absorb glucose from the blood. With a reduction in the insulin levels, kidneys liberate an excess sodium from the body. A keto diet limits a lot of foods rich in potassium. These may include fruits, beans and starchy veggies. Receiving sufficient amounts of these vital nutrients is a superb way to power through the adaptation duration of the diet. Adding potassium-rich, keto-friendly foods such as leafy greens and avocados are an outstanding way of maintaining a healthy balance of electrolytes. These foods contain high amounts of magnesium. And, this mineral helps in decreasing muscle cramps, sleep issues and headaches.

Also Read: Can Quitting Smoking Reverses Diabetes?

Avoid Hard Exercise

Exercise is vital for staying healthy and maintaining a controlled weight. Avoid strenuous exercise while experiencing keto-flu signs. Fatigue, stomach discomfort, and muscle cramps commonly occur in the initial week of following a ketogenic diet. Thus, it might be a good idea to take rest. Activities such as biking, running, weight lifting and harsh workouts might need to be put on the back burner while the body adapts to new fuel sources. Avoid such types of exercise if a person experiences the keto flu. In such cases, light activities such as walking, yoga or leisure biking may improve signs.

Get Enough Sleep

Fatigue and irritation are a few common complaints of individuals who are adapting to a ketogenic diet. Deficient sleep may result in increased levels of the stress hormone cortisol. And, this may negatively affect a person’s mood and worsen the keto-flu signs.

Using Mints

Individuals also use mints to cover keto breath. Slurping mints or chewing mint gum helps in hiding the smell of keto breath. Chewing gum also enhances the amount of saliva produced by a person. And, this helps in preventing the bacterial growth in a person’s mouth. Bacteria which is responsible for bad breath. As per a study, lack of saliva might be a cause of bad breath in the morning. During the night, an individual’s mouth forms less saliva. And, this lets more bacteria to grow.

If a person is facing a difficult time falling or staying asleep, try these tips:

  • Wake up early: Wake up at the same time daily. Also, avoid oversleeping. Both these help in normalizing the sleep patterns and improves the quality of sleep.
  • Lower down the intake of caffeine: Caffeine is a stimulant having a negative impact on the sleep. If a person consumes caffeinated drinks, have them only in the morning. This won’t affect their sleep patterns.
  • Take a bath: Including Epsom salt or lavender oil to bath is a relaxing way to relax and sleep properly.
  • Ensure enough fat and carbs in the diet. 
  • Reduce ambient light: Switch off cell phones, televisions, or computers in the bedroom. This creates a dark ambience and supports a relaxing sleep.

Having enough fat (primary energy source) helps in decreasing cravings. Also, they keep a person feeling satisfied. Low-carb diets aid in lowering cravings for sweets and high-carb foods.

Also Read: Glycomet Diabetes Medication

Why Do People Get This Keto Flu?

People acclimatize to ketogenic diets in a different way. Few might experience weeks of keto-flu signs, while others might adapt to the new diet with no ill effects. The signs individuals experience relates to how their bodies adapt to a new energy source. Carbohydrates offer energy to the body in the form of glucose. On reducing the carbohydrates, body burns ketones from fat rather than glucose.

People who have lots of carbs, particularly refined carbs (pasta, sugary cereal and soda) might face a more difficult time while starting a ketogenic diet. As a result, the change to a high-fat, very low-carb diet can become a battle for few. Whereas, others might be capable of changing fuel sources easily with slight to no keto-flu signs.

The reason why individuals adapt to ketogenic diets than others remain unknown. However, genetics, loss of electrolytes, carbs withdrawal, or dehydration are known to be the driving forces behind the keto flu.

How Long Keto Flu Persists?

The painful signs of the keto flu only persist for about a week for many individuals. Yet, few individuals might face a more difficult time familiarizing to this high-fat, low-carb diet. For such people, signs might persist for a number of weeks. Such signs would slowly reduce as a person’s body gets used to changing ketones into energy. The signs of keto-flu are commonly reported by people shifting to a ketogenic diet.


Individuals with keto flu usually report abdominal signs, headaches, and weakness. The Keto diet is safe and the signs are generally minor and acute. Healthcare providers agree that the keto diet needs strict medical attention to be efficacious for weight loss. To reduce the risk of complications, individuals must begin the diet gradually and visit their doctors regularly. In addition, dietitians may help with easing into the dietary modifications. Incorporating certain dietary changes like having enough fluids and electrolytes helps in managing the signs of keto flu.


Why does a person feel weak on keto?

With inadequate energy in the form of fats, individuals might experience feelings of fatigue or weakness on keto. They’re not consuming in a regular manner. A person’s meal schedule might also have an effect on their energy levels. Consuming regularly is one of the appropriate ways to deliver plenty energy to the body.

Is joint pain a sign of keto flu?

Keto diet contains a rich amount of purine foods. Purine is a chemical that a person’s body breaks down into uric acid. Gout occurs when there’s an excess of uric acid in the blood. Too much of uric acid may produce needle-like crystals in a joint. And, this may result in pain, tenderness, inflammation, and redness.

Does every person get keto flu?

Keto flu is somewhat non-specific and not every person gets it. But nutritionists portray it as just usually not feeling well.

How long after beginning keto does a person gets the keto flu?

Keto flu is a range of signs that might arise 2-7 days after beginning a ketogenic diet. Headache, irritation, nausea, foggy brain, weakness, difficulty sleeping, and constipation are a few signs of this condition.



Last Updated on by Dr. Damanjit Duggal 


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