The ketogenic diet has gained popularity as a natural way to lose weight and improve health.

The diet is very low in carbohydrates, high in fat and moderate in protein.

While the diet is considered safe for most people, it’s associated with some unpleasant side effects.

The keto flu, also called the carb flu, is a term coined by followers to describe the symptoms they experience when beginning the diet.

This article investigates what the keto flu is, why it happens and how to ease its symptoms.

What Is the Keto Flu?

Share on Pinterest
The keto flu is a collection of symptoms experienced by some people when they first start the keto diet.

These symptoms, which can feel similar to the flu, are caused by the body adapting to a new diet consisting of very little carbohydrates.

Reducing your carb intake forces your body to burn ketones for energy instead of glucose.

Ketones are byproducts of fat breakdown and become the main fuel source when following a ketogenic diet.

Normally, fat is reserved as a secondary fuel source to use when glucose is not available.

This switch to burning fat for energy is called ketosis. It occurs during specific circumstances, including starvation and fasting (1Trusted Source).

However, ketosis can also be reached by adopting a very low-carb diet.

In a ketogenic diet, carbohydrates are typically reduced to under 50 grams per day (2Trusted Source).

This drastic reduction can come as a shock to the body and may cause withdrawal-like symptoms, similar to those experienced when weaning off an addictive substance like caffeine (3Trusted Source).

SUMMARY
The keto flu is a term used to describe flu-like symptoms associated with beginning the very low-carb ketogenic diet.

Symptoms
Switching to a very low-carb diet is a major change, and your body may need time to adapt to this new way of eating.

For some people, this transition period can be especially difficult.

Signs of the keto flu may start popping up within the first few days of cutting back on carbs.

Symptoms can range from mild to severe and vary from person to person.

While some people may transition to a ketogenic diet without any side effects, others may experience one or more of the following symptoms (4Trusted Source):

Nausea
Vomiting
Constipation
Diarrhea
Headache
Irritability
Weakness
Muscle cramps
Dizziness
Poor concentration
Stomach pain
Muscle soreness
Difficulty sleeping
Sugar cravings
These symptoms are commonly reported by those who have just begun the ketogenic diet and can be distressing.

Symptoms typically last about a week, though some people may experience them for a longer period of time.