The Keto-Flu

So, you have the keto-flu.  No, you’re not contagious.  No, you can’t pass it on to someone else, or catch it when your friend who follows a ketogenic lifestyle sneezes.

Actually, congratulations are in order. You’ve just experienced the amazing metabolic shift that jump-starts the healing process in your body.  You’re shifting to a metabolism that optimizes the use of fat in the form of ketones.  During this transition, usually within the first week, people can experience a series of symptoms that have been dubbed the “keto-flu.”


What are the common symptoms of the keto-flu?

  • Fatigue
  • Headache
  • Brain Fog
  • Dizziness
  • Nausea
  • Irritability
  • Light-Headedness
  • Leg Cramps

These symptoms can last 3-5 days, in some people I’ve seen it last as long as two weeks.   But, if you weren’t expecting it, and you don’t know what it is, it can be kind of discouraging.  Don’t despair, however, if you know what it is, you can usually do a couple simple things to prevent it, or at least cause the symptoms to dramatically improve.


The keto-flu is usually caused by a shift in your body’s use of water and salt. Insulin causes the kidneys to retain sodium. When you change to a ketogenic lifestyle, your insulin levels fall to baseline and your body is able to use the sodium and potassium to remove the excess water production in each cell from fat burning. (If it didn’t, you’d swell up like beached whale.) This isn’t a bad thing, it just means that you need to add these electrolytes back into your diet in a greater degree.

The average adult human needs 3-4 grams of sodium each day and 3-4 grams of potassium each day to balance out water use and make all the cells happy.  So, what’cha wait’n for? Make your cells happy.

How To Treat It

I find that putting 1/2 teaspoon of salt (I like the Himalayan Pink sea salt because it contains sodium, potassium, magnesium and zinc) in a glass of water cures the symptoms very rapidly, sometimes within minutes. It’s amazing how fast you suddenly feel the brain fog lift and your energy returns.

Another option is using a bouillon or bone broth with your meal. This adds to the overall enjoyment of the meal and replaces these needed electrolytes in a very tasty way.

If the salt replacement doesn’t do the trick, then your keto-flu may be related to the need for more fat. Often, people who start a ketogenic lifestyle cut out the carbs, but don’t put enough fat back into the system.

On the traditional American (or insert your own country of residence here) diet the body uses carbohydrate as its primary fuel and protein for building blocks. When you cut out the carbs, your body will continue to use the protein for building muscle, skin and connective tissue. However, if you don’t give it enough fat to replace the carbohydrate you removed, it’s like running your car on fumes.

You’re body will run for a while, but not very well.  And, in some cases, you’ll feel like you were left on the side of the road with a body that doesn’t want to go anywhere.  You’ll feel like the gas tank is empty.

If you’re not used to a diet higher in fat, your body also has to “fat-adapt,” sometimes called keto-adaptation.  This is the process of your gut and cells up-regulating MCT receptors (fat channels or doorways for fat) to enter more efficiently.  This can take a few weeks, and for some a few months.  Not giving yourself enough fat in a ketogenic lifestyle can slow this adaptation process and also give you keto-flu-like symptoms.

What If It Doesn’t Improve?

If the leg cramps haven’t improved with the replacement of the salts and fat, you might consider yellow mustard.  Mustard contains sinapoline that when metabolized through the acid of the stomach in the body has a byproduct that is similar effect to that of quinine.   Patients, and myself included find that dipping summer sausage or your favorite hard cheese in some yellow mustard before bed does wonders in prevention of muscle cramps or spasm.

If the nausea turns to vomiting, or if the headache or fatigue worsens with added weakness, then it’s time to call your doctor and get checked out.  Vomiting, weakness and worsening fatigue are signs of something more serious.  If this happens, call your doctor.

What About Exogenous Ketones?

Lastly, the addition of exogenous ketones (ketones bonded to a salt) are also very helpful in this transition period.  Drinking exogenous ketones provides added ketones, rapidly absorbed into the blood stream, and second they provide some of the sodium, potassium or magnesium needed as a replacement.  You can check out my Ketogenic Kick-Start packages here.  Or, you can go to Dr. Nally’s favorite ketone store at and order them directly.

Either way, I hope you find this helpful as you transition to your Ketogenic Lifestyle.

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