Keto Flu

The ketogenic diet has been gaining massive popularity in recent times as a healthy and natural way to lose weight. The diet contains high fats, moderate protein, and very low carbohydrates. While some people may enjoy a smooth transition to the diet, others may experience some unpleasant side effects.

The keto flu or carb flu is a name used by followers to describe the symptoms they encounter when beginning the keto diet. This article explains what the keto flu is, why it occurs, and how to alleviate its symptoms.

What is the keto flu?

The keto flu is a body of symptoms experienced by some people when they start a keto diet.

These symptoms are triggered when the body notices a shortage in the supply of carbohydrates from your diet.

This shortage forces your body to go into a state of ketosis where it burns ketones instead of glucose. Since ketones are only used as a secondary fuel source, it is only used when there is a shortage of glucose in the body.

Ketosis can be triggered during certain circumstances, including fasting and starvation. It can also be achieved by adhering to a very low-carb diet such as the ketogenic or ketosis diet where carbohydrates are reduced to below 50 grams per day.

This extreme reduction can come as a shock to the body and induce withdrawal-like symptoms that closely resemble those experienced when laying off an addictive substance like caffeine.

What are the symptoms of the keto flu

Some people find the transition to a low-carb diet, but for some, this process may be quite distressing.

Your body may start showing signs of the keto flu within three days of cutting back on carbs, and symptoms may vary from mild to severe, depending on the individual.

One or more of the following symptoms can be experienced.

  • Nausea
  • Difficulty sleeping
  • Vomiting
  • Diarrhea
  • Headache
  • Constipation
  • Weakness
  • Irritability
  • Muscle cramps
  • Poor concentration
  • Dizziness
  • Muscle soreness
  • Sugar cravings
  • Stomach pain

These are common symptoms reported by individuals who just began a low-carb diet, and they typically last for a week or longer depending on the severity.

While these signs may cause dieters to throw in the towel, there are ways to limit them.

How do you reduce the symptoms of keto flu?

The keto flu can be distressing; thankfully there are several ways you can limit the occurrence of the flu-like symptoms and help your body go through the transition easily

Stay hydrated

Drinking enough water is good for your health and also helps reduce the symptoms. You may feel dehydrated as the keto diet can cause you to lose water stores rapidly.

This occurs because water binds with glycogen in the body. When there is a reduction in dietary carbs, the glycogen levels drop, causing fluid loss.

Drinking enough water can help with symptoms like muscle cramping and fatigue.

Avoid vigorous exercises

Even though workouts are essential for maintaining body weight and staying healthy, you should avoid intense workouts when experiencing keto-flu symptoms.

Stomach discomfort, fatigue, and muscle cramps are usually noticed during the first week of starting a keto diet. Therefore, you must give your body some rest.

While your system gets used to its new energy source, you should cut out activities such as intense biking, weight lifting, running, and strenuous exercises for the time being. If you must stretch your muscles, make sure to perform only light activities like yoga, walking, or leisurely biking.

Get enough sleep

Irritability and fatigue are common signs of keto-adaptation. Not getting adequate sleep causes an increase in the levels of the stress hormone cortisol, which can cause mood swings and worsen the keto flu symptoms.

Try one of the following if you find it hard falling or staying asleep.

  • Get up early: limiting oversleeping and waking up at the same time each day may help regularize your sleep pattern and enhance sleep quality over time.
  • Reduce caffeine consumption: caffeine is a stimulant that keeps you awake for long hours. Try limiting your intake to only mornings, so it doesn’t disturb your sleep at night.
  • Turn off ambient light: switch off cellphones television and computers at least an hour before bedtime to create a dark environment and encourage restful sleep.
  • Take a bath: adding lavender essential oil or Epsom salt to your bath can help you relax and get ready for sleep.

Replace electrolytes

Switching to a keto diet reduces the production of insulin, an essential hormone in the body that absorbs glucose from the bloodstream.

As insulin levels drop, the kidney starts releasing excess sodium from the body. Plus, the keto diet restricts many potassium-rich foods, including beans, starchy vegetables, and fruits.

Getting an adequate amount of these essential nutrients is an effective way to scale through the transition period.

You can keep a healthy balance of electrolytes by salting food to taste and including keto-friendly, high potassium food like avocados and green leafy vegetables into your diet.

What’s more, these foods may also help in managing symptoms like headaches, muscle cramps, and sleep issues due to their high magnesium content.

Make sure you’re consuming enough fat

When adapting to a low carb diet, you may start craving foods that are restricted in the keto diet such as pasta, bread, bagels, and cookies. Eating enough fat, the main source of fuel in the keto diet, will help reduce Cravings and boost satiety.

However, you should try cutting out carbs gradually rather than all at once to reduce the flu-like symptoms and make the transition smoother.

Why do people react to keto-adaptation?

People react differently to keto-adaptation. While some people may struggle with flu-like symptoms for some weeks, others may experience a smooth transition with no adverse side effects.

The symptoms people experience has to do with how their body adjusts to a new fuel source. Usually, the body runs on glucose gotten by burning fat. But when there’s a substantial decrease in the intake of carbs, the body switches to burning ketones from carbs.

People who consume more carbs, especially refined carbs like sugary cereal, soda, and pasta, may find it difficult to switch to a ketogenic diet than others.

There is no known reason as to why people experience keto-adaptation differently. Still, dehydration, electrolyte loss, carbohydrate withdrawal, and genetics are believed to be the driving forces behind the keto flu.

How long does the keto flu last?

Luckily, most people only experience flu-like symptoms for about a week. However, some individuals may have a more difficult time getting used to this low-carb, high-fat diet. These individuals may experience the symptoms for several weeks

Fortunately, the symptoms will gradually subside as your body gets used to burning ketones as energy.

However, you’re advised to seek medical attention if you’re feeling particularly unwell and experiencing symptoms like prolonged diarrhea, vomiting, or fever.

Who should avoid a low-carb diet?

Although the keto diet may be beneficial to a lot of people, it is not suitable for everyone

For instance, in the ketosis diet may not be safe for breastfeeding mothers, pregnant women, children, and teens unless it’s being used for therapeutic purposes under medical supervision.

Plus, this diet is not suitable for people with certain health conditions like liver disease, kidney disease, or pancreatic conditions.

Those with diabetes who are interested in switching to a ketogenic meal plan should see their doctor or dietitian to determine if this diet is safe and convenient for their specific needs.

Lastly, this diet should be avoided by people who are hypersensitive to dietary cholesterol, who constitute about one-third of the world’s population.

Bottom line

The keto flu is a bunch of signs and symptoms associated with the adaptation of the body to a ketogenic diet.

Some people may experience nausea, sugar craving, fatigue, and headache while transitioning to a high-fat, low carb diet.

You can reduce flu-like symptoms by getting enough rest, staying hydrated, replacing electrolytes, and ensuring your food intake contains adequate amounts of fats and carbohydrates.


  • Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets – NCBI
  • The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus – NCBI
  • The Keto Flu: Symptoms and How to Get Rid of It – Healthline
  • What is keto flu? – Harvard Health