What is the Keto Flu

When first starting a Ketogenic Diet some people can feel fatigue, headache, dizziness and other symptoms that are usually not very pleasant. These are commonly known as Keto Flu when in a context of Keto Diet. But, actually, what is the Keto Flu?

What is the Keto Flu

What Is The Keto Flu

I should start with, don’t worry! Not everyone experiences this side effect when starting a Ketogenic Diet and in the majority of the cases is not as bad as it sounds.

It is still beneficial to know what is the Keto Flu though.

The Keto Flu is a normal consequence of the Ketosis process which presents itself with Flu-like symptoms.

The name comes from the symptoms linked to it, which are mostly flu-like symptoms, that is why “Keto Flu”.

Why The Keto Flu Happens

As we mentioned, the Keto Flu is a consequence of entering Ketosis and it is useful to know the reasons why it happens.


The average person has a body that runs on carbs, and has been doing so for years in many cases.

You also know that the Ketogenic Diet cuts your carbs intake forcing your body to use fat instead carbs to get energy.

When your body has to switch from one fuel (carbs) to another (fat) it can go through a shock.

It has to adjust its chemicals, hormones and processes so that it can efficiently burn fat to retrieve energy.

During this time of adjustment the person might experience symptoms very similar to a flu.

Electrolyte Imbalance

Another factor that can cause a Keto Flu is an Electrolyte Imbalance.

Starting a Ketogenic Diet can usually result in an increase of water intake.

The change of nutrition and the start of the Ketosis also decrease your water retention and increase your urination.

These two events can cause your body to flush important substances from your body, including Electrolytes.

An imbalance in your electrolyte levels can cause symptoms similar to a flu.

What Are The Keto Flu Symptoms

The Keto Flu can cause the manifestation of some symptoms and these may vary for each individuals.

Some people may not experience any symptoms while some others could experience a more severe flu-like situation.

These are the most common symptoms experienced:

  • Fatigue
  • Sugar cravings
  • Dizziness
  • Difficulty focusing (or Brain Fog)
  • Nausea
  • Difficulty getting to sleep
  • Irritability
  • Stomach irritability
  • Gastrointestinal stress

Keto Flu Remedies

This “flu” usually manifests itself during the adaptation phase, basically when the Ketosis starts, or just after it.

The duration of this flu depends on the individuals and usually does not last longer than a few days.

However, you can help your body to mitigate the symptoms and get over it quickly.

These are some methods that can help relief some of the symptoms:

  • Eat more fat, cutting carbs also means more energy to function, increase your fat intake to compensate
  • Eat more calories, maybe you cut too many calories together with your carbs, watch your calories intake
  • Eat a Few More Carbs, cutting carbs is still a requirement to start Ketosis, however, cutting too drastically can have too negative effects, try cutting slowly
  • More Salt, it will help with water retention
  • Drink Enough Water, it is important to keep your body hydrated
  • Reduce External Stress, your body is already undergoing a stress due to the metabolic changes, try to minimise external stress
  • Exercise Before Starting, if you are used to exercising before starting a Keto Diet your body will suffer less to adapt to the new conditions

As you can see there are many ways you can help your body before and during a Keto Diet.


If you are considering a Ketogenic Diet you need to know that you could experience a Keto Flu.

What is the Keto Flu? It is a normal consequence of forcing your body to switch from one source of energy (carbs) to another (fat).

It is due to mostly to a phase of adaptation and can result in many flu-like symptoms.

Not everyone experiences the Keto Flu, but in case it does, it usually does not last longer than a few days.

You can also help your body mitigating the effects with some attention to your nutrition.

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