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How to Survive the Keto Flu

How to Survive the Keto Flu

One of the very first problems that someone who is starting out on a ketogenic diet will come across is the keto flu. To my personal shame, I suffered a fairly bad bout of this myself. I had read several articles beforehand warning of the danger., but all to no avail. I started into my new lifestyle with great enthusiasm and within four or five days found myself struggling with the dreaded malady.

the healthy keto plan book by eric berg

What is the Keto Flu?

The keto flu is a range of symptoms suffered by the neophytes into the ketogenic diet. It generally comes with a range of symptoms including, but not limited to, the following:

  • Brain fog
  • Headache
  • Nausea
  • Insomnia
  • Irritability
  • Feelings of Weakness
  • Lack of Energy
  • Muscle Cramps
  • Diarrhoea
  • Constipation

How long does it last?

Usually, these symptoms will last somewhere between a week and ten days. Unfortunately, many people new to the diet give up at this early phase. Such an attitude merely ensures that they never experience the benefits of a ketogenic diet. My own experience of keto flu manifested mainly as lethargy, poor sleep and muscle cramps. The latter were particularly painful. Also, during my customary cycle rides, I could barely keep up with my wife. My usual ten-mile forest course felt incredibly challenging to complete. By the end of a session, I felt exhausted.

At night, when I should have been resting, I found it hard to sleep. When I did manage to nod off, my slumber would often be disturbed by really quite agonising night cramps. I would be the first to admit that it was not easy.

Whilst playing with my son, I would experience feelings of nausea, dizziness and weakness. The dizziness in particular gave me pause for thought. Was I really being wise to continue such an experiment?

The Promised Land

After suffering these problems for something like ten days, something magical happened. Almost imperceptibly, my body got used to the idea of using ketones for energy and slowly, but very surely, things got better. As I neared the end of a particular cycle ride, over the same cross country route, I suddenly realized that I still felt full of energy. I recall sprinting quite joyfully over the last half mile or so, confident in the flow of energy I was now experiencing.

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The energy one experiences when one is in ketosis is quite different from the normal ‘sugar spikes’ of a system running on glucose alone. It is deeper in nature. You feel calmer and steadier. You also feel like you could grind out whatever challenge faces you for hour after hour. This is one of the gentler joys of being in ketosis.

How to avoid the Keto Flu

If you wish to try to avoid the keto flu, or at least make it bearable, some simple measures are called for. The first and foremost among these is staying hydrated. There is often a huge loss of water in the first couple of weeks of a ketogenic diet. This is because your body doesn’t need to hold onto so much water as it is no longer needed for processing so many carbs. It is called carboHYDRATE for a reason. For every gram of carbs that the body stores there are two to three grams of water retained. As you lower your carb intake, you will lose much of this excess water. This process is quite natural but beware of the dangers of losing too much. Make sure to drink enough.

Secondly, it is wise to ensure that your body is supplied with sufficient electrolytes. In particular, Sodium, Potassium and Magnesium. Towards the end of my keto flu period, I would take a pint of salted water to bed with me each evening. This greatly improved the situation in regard to the awful cramps I was suffering. Salt is an interesting subject in itself. It has been vilified so much in recent decades, yet it is vital to imbibe appropriate amounts if you wish to stay healthy.

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electrolyte supplement for keto flu

Thirdly, be gentle with yourself. Try to take it slowly and gently. If you cannot sleep, at least make sure you get sufficient physical rest. If you are exercising, try to make sure the sessions are not too challenging in these first few weeks of keto. Try to keep other stresses in life at an easily manageable level.

Finally, make sure you are getting enough fat in your ketogenic diet. This may seem obvious, but because some people carry the psychological residue of years of being told how bad fat is, they struggle to get themselves to eat it in sufficient quantities. Effectively, in keto, you are starving your body of its normal glucose from carbohydrate. Therefore, you must replace this with the macronutrient that allows for the production of ketones: fat.

Challenges from the Keto Flu

Although there are a whole range of adjustments you can make, it still may not be plain sailing. You may well suffer some degree of discomfort in those first couple of weeks or so. The results will be worth it, and this must be borne in mind if and when you go through the keto flu.

It is quite possible that you could conscientiously carry out all the measures recommended above and still have problems. With the keto diet, we are asking the body to undergo a deep and dramatic change. Fundamentally, you are moving from carbohydrates to fats as your primary source of energy. This is no trivial matter.

In my case, I had been vegetarian for decades before switching to keto. For others, it may not be so long, but it is still a very profound change that is being attempted. Given that, we shouldn’t be surprised if we go through some initial challenges.

When we start into something like the keto diet, we can let enthusiasm get the better of us. Some people wish to go from literally hundreds of grams of carbs a day to none at all in one, simple step. This can be done, but you are likely to suffer a more dramatic reaction if you follow such a route.

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Many argue about the exact level of carbs that should be allowed on a ketogenic diet. The recommended figures are usually somewhere in the range of zero to fifty grams a day. At the start of a ketogenic diet at least, and with the benefit of hindsight, I would say it’s wiser to be more generous with the carbs at the start. If you stray over to sixty or seventy grams of carbs it will not be the end of the World. As you go deeper into the keto lifestyle, you can readily reduce those carbs below fifty over time, and then below thirty. In the meantime, be gentle with yourself!

Knowing when you are coming out of Keto Flu

Over time, with patience and persistence, these challenges can be overcome. Despite your best efforts though, you may still have a few problems with the ketogenic diet at the start. Keto flu is probably the most common of these. The measures recommended in this blog will certainly help to mitigate these problems, but you still may not avoid them altogether. If you stay with it though, these short term challenges will fade away. The manifold benefits of the ketogenic diet and lifestyle will then manifest in your life more and more over time.

the ketogenic bible book


Keto flu is clearly a major challenge for many starting out on the keto diet. There are measures we can take to either avoid it or at least mitigate the worst of the symptoms. There are no guarantees though. Even after taking all these measures, you may still have a difficult time for a few days. On the positive side though, and with an adequate amount of determination, you will get through this phase and increasingly thrive on the ketogenic diet.


14 thoughts on “How to Survive the Keto Flu

    1. We try to create one or two articles a week, at least for now. It may go down to one if we examine another health related area we are interested in.

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