The keto flu,
other keto side effects,
and how to cure them

So you’ve just started a keto diet, and you feel poorly. You’re tired and you have a headache, you’re easily annoyed and have a hard time concentrating.

Congratulations, you have the keto flu. That’s what people call it, though it’s not really a flu, and it’s not contagious. It can just feel like a flu.

Most people feel some of these symptoms during the first week of a keto diet, especially day 3-5. Fortunately it’s temporary and you’ll feel fine again soon. Even better, there’s a simple fix1 that usually cures most or all of the symptoms in 15 minutes. Keep reading to find out!



The keto flu

Keto fluSymptoms of the keto flu:

  • Fatigue
  • Headache
  • Irritability
  • Difficulty focusing (“brain fog”)
  • Lack of motivation
  • Dizziness
  • Sugar cravings
  • Nausea


The cause

The keto flu is caused by the transition when your body starts burning fat for energy instead of sugar.

Most of the symptoms are caused by a lack of water and salt, caused by a temporarily increased urine production as the body enters ketosis (the increased fat-burning mode).

This can be compensated for, effectively curing the keto flu.


The cure for the keto flu

The symptoms of the keto flu usually disappear by themselves within a few days, as the body adapts. But to get rid of them in 15 minutes, use this cure. The first step is by far the most important, and it’s often enough.

1. Top tip: increase salt & water

Salt & waterDuring the transition to being a fat burner, if you increase your intake of salt and water, keto flu symptoms can be reduced if not eliminated.

During the first few weeks, whenever you feel a headache, lethargy, nausea, dizziness or other symptoms, drink a glass of water with half a teaspoon of salt stirred into it. Doing so may alleviate keto flu symptoms within 15 to 30 minutes. Feel free to do this twice a day or more.

Or for a tasty alternative, drink consommé, bouillon, bone broth, chicken stock or beef stock — and feel free to stir in a spoonful of salted butter. Or, if the broth is low in salt, put in a pinch.

Learn more about electrolyte supplementation on a keto diet

2. More fat, fewer symptoms

Adding more salt usually removes most keto flu side effects. If you are still feeling poorly, eat more fat.

Longstanding fat phobia is common among people who come to low-carb ketogenic eating. If, however, you cut your carbs without upping your fat consumption, your body will think you are starving. You will feel tired, hungry and miserable.

A well-balanced keto diet includes enough fat so that you are not hungry after a meal, and you have ample energy. Up the fat at the start of you keto journey until you are adapted as a fat burner. Once adapted, you can cut back a little bit on the fat until the point that you can easily maintain the balance between hunger and satiety.

In short: when in doubt, add fat (mmm, butter). Or follow our keto recipes, which have enough fat in relation to carbs and protein.

3. Slower transition

More water, salt and fat not helping? Still feeling achy, tired and off? We recommend you endure for a few more days until the symptoms pass — this is best for weight loss and for metabolic issues like type 2 diabetes. Keto flu symptoms will be temporary — they’ll be gone when you are a fat-burning machine.

You can, however, slow down the transition to ketogenic eating by consuming a few more carbs, such as following a more moderate low-carb diet, eating 20 to 50 grams of carbs a day

Eating slightly more carbs may slow weight loss and mute dramatic health improvements, but it still can be an effective way to help improve your health, especially if you are cutting out sugar and processed foods. And keto flu will not be an issue.

Dr. Eric Westman’s tips

LCHF the right way
Learn more about getting the best results and the least side effects on a ketogenic diet from world renowned keto expert Dr. Eric Westman. His five-part video course is on our membership site (one month free trial).

In video #3/5, he discusses how best to avoid transition problems like keto flu.



Other common issues on keto

There are several possible side effects on keto, not just the initial keto flu. Use the links below to learn more:


Less common keto issues




A ketogenic diet for beginners
Ketogenic diet food list – what to eat

  1. More water and salt, see below…