Keto 101: What is Keto Flu (And How to Cure it)

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What is the keto flu?

The keto flu happens when your body is transitioning to the keto diet.

It actually feels like you’re coming down with the flu - you feel sick. Headaches, nausea, dizziness, feeling tired and run down with a lack of energy and maybe even discomfort.

What are keto flu symptoms?

Symptoms can include

  • Dizziness

  • Weakness

  • Fatigue and lack of energy

  • Mental fog

  • Nausea

  • Cramps and sore muscles

  • Stomach pain

  • Constipation

  • Sore throat

  • Insomnia

  • Sugar cravings

Why does the keto flu happen?

When you transition to a keto diet, you’re drastically cutting down on the carbohydrates you’re putting into your body.

When the body processes carbohydrates, it uses a hormone called insulin to move the carbohydrates into cells. This happens every time that you eat carbohydrates.

When that happens, the body suddenly realizes that it doesn’t need to process as many carbohydrates anymore, so things change.

Since your body doesn’t need to process as many carbohydrates, it decreases the amount of insulin it produces.

When it decreases the amount of insulin it produces, the body undergoes other changes. It starts using the stored carbohydrates in your body (stored in the form known as glycogen) for fuel.

When carbohydrates are stored as glycogen, it also stores water along with the carbohydrates. When your body starts tapping into that glycogen, it releases the carbohydrates - and also a lot of that water.

You’ll have to pee a lot. And when that happens, you also pee out a lot of your electrolytes - sodium, potassium, calcium and magnesium.

When you lose those electrolytes, it will cause the keto flu.


Since we know that the electrolytes being depleted causes the keto flu, we can reverse it - or even prevent it - by making sure we consume a lot of electrolytes when going on keto.

There are many ways of getting your electrolytes, but the most effective way I’ve found is drinking broth with plenty of half-salt - salt that is half potassium, half sodium. I do this in the morning as soon as I get up to ensure I get a good supply of electrolytes for the day.


I’m not sure how we got around to demanding people drink eight glasses of water a day. It seems like it might be a conspiracy of the bottled water industry perhaps, but you don’t need to be drinking eight glasses of water a day.

In fact, you should actually decrease the amount of water you’re drinking on the keto diet - you’re more in danger of drinking too much water than not enough.

Think about it this way: If the keto flu is caused by the depletion of electrolytes, then by drinking too much water, you’re going to further deplete your electrolytes.

I’m not saying not to drink water - but don’t overdo it. Drink if you’re thirsty, but don’t go gulping gallons of water.

Don’t worry - this too shall pass

As your body gets used to the keto diet, you’ll find the keto flu going away. It will become less severe, and then one day you’ll be free of it completely.

Like anything else, your body adapts - and in this case, it’s usually pretty quickly, especially if you’re supplementing with enough electrolytes. You’ll be back to normal before you know it!

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