What is ‘keto flu’ and how do I avoid it?

By Dr. Stephen Phinney and the Virta Team

Nutritional ketosis flu, more commonly referred to as keto flu, may occur in the beginning phases of nutritional ketosis as you are dramatically reducing the amount of carbohydrates you are consuming. No need to worry though, this is not actually the flu and it is not caused by being in a state of nutritional ketosis! Rather, the ”flu-like” symptoms that some individuals experience when starting the ketogenic diet is due to the body’s response to carb restriction.

When you begin to restrict carbs from the diet, the kidneys (the body’s filtration system) switch from retaining sodium (aka salt) to rapidly excreting it, along with excess water in the body (Volek, 2011). During the clearance of extra sodium and water from the body, many people experience rapid weight loss. While it may be exciting to see the scale move in a downward direction, know that this is not true weight loss from fat, but instead from the water loss. Therefore, it is important that you replace some of the sodium and water that you are excreting because if these are not replaced, it is likely that you will experience symptoms of keto flu.

Symptoms of keto flu include:

  • Lightheadedness
  • Fatigue—especially around exercise
  • Headache
  • Constipation
  • Nausea

Luckily, these symptoms can easily be minimized or even prevented! The easiest way to minimize/avoid keto flu is to increase your salt intake by 1-2 grams/day—rest assured, while you are in nutritional ketosis you will not store this extra sodium in the body.1

An easy way to increase your salt intake is by drinking 1-2 cups of bouillon a day because each cube contains about 1 gram of sodium. Although drinking bouillon or broth might sound a little strange, it can actually be quite delicious. If you add a little butter and/or heavy cream to it you can create a savory ‘tea’ that is also a great source of fat, salt, and additional water!  Even better, make your own ‘bone broth’ from leftover roast chicken, beef bones, or ox tails. It can be made in batches of 8 – 16 cups at a time and stored in the fridge or frozen for later use.  When made properly, in addition to 1 gram of sodium, one cup provides other beneficial minerals and about 7 grams (equivalent to one ‘ounce’) of protein.

Citations:

Volek JS, Phinney SD.  The Art and Science of Low Carbohydrate Living.  2011. PP 41.  Beyond Obesity Publishing, Miami FL.

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12 Comments

  1. Avatar

    I don’t know but I feel fine yes last week though I went to the hospital I fainted because I was dehydrated now I know now I feel at times with growling in my stomach and stomach pain including diarrea I am conconerned because I don’t want to pass out again and feel constupated help

    Reply

    1. Virta Health

      Perla, We are unable to provide specific medical advice via this forum. We definitely recommend working with your healthcare provider.

      Reply

  2. Avatar

    How long does it take to reverse keto adpatation, once fully adapted?

    Reply

    1. Virta Health

      Great question! Dr. Phinney has previously written, “In our clinical experience with human patients, however, we typically find that more than a few days of ‘falling off course’ can reverse keto-adaptation and take from several days to up to a week or more to fully recover. The timeline for this likely depends on one’s level of insulin resistance and the amounts of carbohydrate consumed.”

      Reply

  3. Avatar

    Virta team-

    I know you can’t individually address specific problems, but, generally speaking, if one were to go longer periods without correcting a sodium deficiency caused by a ketogenic diet, or say, the flu, would these guidelines correct a longterm deficiency? Or, would it be necessary to increase the amount for a brief period and then settle back into the four gram range for overall well being. I’ve read in the past that approximately two grams of sodium is needed for every liter of lost fluid. However, I’m not sure how accurate that is. Thanks for any advice.

    Reply

    1. Virta Health

      Hi Chris! It would really depend on how severe the depletion was. This would be a good starting point but wouldn’t be appropriate if someone was experiencing severe side effects.

      Reply

      1. Avatar

        Thanks so much for the reply and great work you are doing.

        Reply

  4. Avatar

    Thanks for the reply, and hopefully, you have time for a quick follow up. Could you all comment on rehydration and electrolyte formulas containing glucose. I understand the expedited uptake of sodium when glucose is added via the small intestine.
    However, if salt is taken with water or broth, is the absorption substantially less or just slower?
    If one were suffering from an acute illness like a stomach bug or flu, would breaking ketosis in order to expedite electrolyte uptake via an ORS solution be advised, or would drinking water or broth with added salts be sufficient, and obviously keep one in ketosis at the same time.
    I guess what I’m getting at is; can you rehydrate properly without additional glucose from a moderately dehydrated state.
    Thank you and Once again, thank you for providing such a great forum to the public.

    Reply

    1. Virta Health

      Hi Chris! Our patients are encouraged to consume electrolytes without added glucose during times of acute illness, with homemade broth or bouillon being great options. The electrolytes will support rehydration without the added stress of increased blood glucose levels.

      Reply

  5. Avatar

    Thank you! That clarifies a great deal for me. I truly appreciate it.

    Reply

    1. Virta Health

      You’re so welcome!

      Reply

  6. Avatar

    After one day of doing the vegetarian keto diet I’ve woken feeling quite ill, I freaked out and had a bowl of some cereal to try and make myself better as I have little ones to look after and things to do so being ill for me is out of the question but I don’t want to give up the keto diet, I had very bad Diarrhea, nausea, bad head, the shakes and feeling very weak, I normally try to follow a vegan lifestyle but allowed myself to have dairy for the keto to make things not so hard for myself with the intention of going full vegan on keto once I’m use to it so I suppose having cheese when I don’t normally may have upset my body a little

    Reply

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