how long does keto flu last
how long does keto flu last

How long does keto flu last?

Many overly weighed people feel like the perfect solution that can help reduce their size is dieting. They engage on a diet journey where they stay away from carbs (ketogenic diet) resulting in a condition known as keto flu.

A diet primarily composed of low carbs(carbohydrates) is known as a ketogenic diet.

The body normally burns carbohydrates for energy but when there are no carbs to be burned, the body substitutes the carbs with fat leading to a condition known as ketosis.

The metabolic process of ketosis

How long does keto flu last
How long does keto flu last

The infographic above summarizes the metabolic process of ketosis i.e. the different processes in ketosis.

A reduction in the intake of carbs is interpreted by the body as a confusion, it is habitually or normal for the body to burn carbs for energy but now, there seems to be a lack of carbs so, the body uses fat as a substitute.

  • Introduction of the ketogenic diet.
  • Scarcity of carbs
  • Body searches for a substitute
  • Fat is burned for energy instead of carbs.

What is keto flu?

In simple terms “keto flu” is a group of symptoms that occur as a result of carbs withdrawal (ketogenic diet) I.e. how your body reacts to intake of ketogenic diet (food low in carbs).

The body is familiar with the balanced diet but when there’ an abrupt cessation of carbs, the body and brain are forced to adjust to the low carbs level hence the keto flu.

Keto flu is a group of symptoms that occur 2-7days after a change from a balanced diet to a ketogenic diet.  It consists of flu-like symptoms that is experienced by people who engage in a ketogenic diet.

Why does Keto flu happen?

The main source of energy to man is carbohydrates and it is recommended to consume over 200-300 grams of carbs every day.

When you continually take less than half of the recommended daily intake of carbohydrates, the body interprets this as a deficiency in carbohydrates because the amount of carbs taken in is not sufficient to provide the energy the body requires.

The body makes up for this carbs deficiency through a process known as glucogenesis.

Glucogenesis is a process where the liver produces glucose stored up in order to supply the body with energy. This goes well for a while but at some point, the amount of glucose stored up will not be able to completely provide all the energy required by the body.

Fatty acids are burned up by the body through a process known as ketogenesis, when the body uses fat as energy, this process is referred to as ketosis.

Therefore keto flu occurs when our bodies change from the normal burning of carbs for energy to the burning of fat.


The loss of electrolytes and fluid could be the most valid reason for the flu.

The most important goal of a ketogenic diet is to reduce the insulin level in the body. When the body switches from burning carbs to burning fat for fuel, the resultant symptoms (from cellular to hormonal level) are referred to as keto flu.

The reduced level of insulin stimulates the liver to begin the conversion of fat to ketones so that the body can use this for energy in place of glucose.

Several organs of the body may not quickly adapt to this new source of energy. The level of insulin drops and the kidneys tends to release excess sodium this leads to a rapid loss of water(polyuria) and sodium.

The frequent loss of water and sodium is likely responsible for the symptoms of keto flu.

The level of T3 thyroid hormone may also fall as there seems to be a relationship between dietary carbs and T3 thyroid hormone.

Key facts

  • Loss of water and sodium
  • Low insulin levels
  • Reduction in the level of T3 thyroid hormone

how long does keto flu last

How long does keto flu last

The symptoms can begin within two to seven days of the diet switch and last for a few days, a week, or a month.

The duration of the flu is dependent on the genetics of the person and the mildness or severity of the symptoms

Symptoms of keto flu

Nutritional ketosis is actually safe for most people from the medical point of view. However, most people that engage in a ketogenic diet may experience some symptoms including dizziness, nausea as a result of the loss of water and electrolytes.

Symptoms might differ for different people and it usually begins within the first few days of the diet switch.

Symptoms can last for a week or more but in severe cases, it can last longer than a month.

The keto flu signs range from mild to extreme symptoms, studies have shown that the symptoms vary from person to person I.e a person might engage in ketogenic dieting but will experience no symptoms while another person might experience mild to severe symptoms.

The most common symptom of keto flu or keto induction is;

DehydrationThe excessive increase in the number of electrolytes (sodium, potassium) present in the urine causes dehydration. The water retention capacity of the body is fostered by carbs, therefore a decrease in the intake of carbohydrates affects the ability of the body to hold water(polyuria).

Other symptoms of keto flu include;

  • Headache
  • Dizziness
  • Insomnia (difficulty in sleeping).
  • Nausea
  • Lack of focus and coordination
  • Increased craving for sugar
  • Tiredness
  • Muscle cramps
  • Stomach pain
  • Weakness
  • Diarrhea
  • Constipation

How to manage keto flu

A lot of people quit their ketogenic dieting during the first week due to the way their body reacts.

Most of these symptoms are short term, it’s just your body ways of reacting to these new changes it is experiencing.

  1. Dehydration is a common symptom of keto flu and in other to combat this, you must stay hydrated.

Drink water regularly to make up for the amount of your loss due to the low intake of carbs.


  1. When experiencing keto flu symptoms, stay off hard tasking jobs, exercises, or chores. Engage in easy and less strenuous activities.


  1. Lack of sleep can worsen flu symptoms and negatively influence your mood. A good hour of sleep is highly recommended for an effective diet switch.


  1. The body tends to lose lot of electrolytes such as potassium and sodium while experiencing the keto flu. A replacement should be made, eat food and fruits (avocado, banana) that are very rich in potassium and sodium.