Keto Flu: What, Why, and How to Beat It

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Starting out on the keto diet is an exciting time. You have lots of changes ahead of you – fat loss, increased energy, and heightened mental clarity – but for many new keto followers, the first days can be pretty miserable.

As your body adjusts to eating fewer carbs, you may actually feel worse before you feel better. Keto veterans call this phenomenon the keto flu.

Fortunately, this is just temporary, and you’ll quickly see the benefits as long as you stick with it.

What is the Keto Flu?

Following a keto diet means forcing your body to make energy in entirely new ways. This can be difficult for your body to do at first.

If your pre-keto diet was filled with sugars, additives, and empty calories, then your body is going to have to make some big adjustments. During this adjustment period you may find yourself feeling slightly off, or even ill.


While not everyone experiences the keto flu, those that do report almost identical symptoms:

  • Nausea
  • Mood swings
  • Mental cloudiness
  • Headaches
  • Fatigue

It’s not hard to see why the keto community refers to these symptoms as a “flu.” You might think you’ve come down with a bug, but if you’ve just started a new keto diet it’s very likely that your body is actually at fault.

These symptoms can seem unbearable at times, but I promise you from my own personal experience that pushing through the discomfort is totally worth it. This is only temporary and afterwards you’ll feel better than ever.

The more carbs you ate pre-keto, the worse your keto flu will probably be. But once your body realizes it no longer needs carbs to function, you’ll find that these symptoms quickly disappear.

What Causes the Keto Flu?

In case you didn’t already know, the keto diet requires eating a very small number of carbs per day.

The average person eats a ton of carbs, often upwards of 300 grams a day. While some lucky people function just fine on this many carbs, others do not.

If your body is used to getting a large number of carbs to use for energy and store as fat, then suddenly “quitting” carbs is going to put your body into shock. But just because your body craves carbs does not mean that they are necessary or healthy.

The new lack of carbs will make your body think it is missing something, but the truth is that your body has just grown dependent on sugar and carbs. This withdrawal is what causes the keto flu.

The hardest part of the keto flu is resisting the temptation to eat carbs. Your mind and body will tell you that the quickest way to feel better is to indulge in a slice of bread or piece of candy, but you’ll only be prolonging your symptoms. Trust me, it’s not worth it!

After a couple days have passed you’ll begin to get back to normal, and will even feel better than before you started.

Alleviating Your Symptoms

While the only way to really cure the keto flu is to wait, you can help ease the symptoms by keeping your electrolytes up.

In the average person’s body, carbs hold onto a huge amount of water and electrolytes. When you suddenly cut carbs out of your diet your body loses excess water weight, which means you will lose some electrolytes as well.

While you should drink more water to replace these fluids and prevent water retention, this won’t help replenish your body’s electrolytes. Instead, you must supplement your diet with magnesium, potassium, and sodium.

The best way to supplement your magnesium and potassium is with an electrolyte-filled drink mix like Ultimate Replenisher. These mixes are a quick and easy way to ensure you’re getting the necessary electrolytes, and they taste great too!

Sodium is pretty easy to supplement, as all you need to do is add extra salt to your food. You can also add some high sodium foods to your meals, like bacon.

Another famous keto trick is to drink a cup of zero carb chicken broth or pickle juice to alleviate your flu symptoms.

While supplementing your electrolytes might not cure your keto flu, it will definitely make the adjustment period more bearable!

Adjusting to Ketosis

When you decide to follow a keto diet, you are deciding to make your body run on fat instead of sugar.

Using fat for energy can be healthier and more efficient than using carbs, but your body will still need to adjust to this new way of operating. Once your body has adjusted to the keto diet, it will be much easier for you to lose body fat.

This adjustment period and the flu symptoms that go along with it can vary in length for each person. Some new keto followers only feel ill for a day, while others can suffer for up to a week.

These differences can depend on your individual body and your lifestyle before adopting the keto diet, but everyone will come out the other side feeling healthier. After you push past the keto flu you will start to see the fat disappear from your body.

In addition to electrolytes, you must also make sure you are eating enough fat. Remember that your body is now using fat instead of carbs for the majority of its energy, so you need to compensate by significantly increasing your fat intake.

You can achieve this by eating fattier cuts of meat and adding butter or oil to your meals, but you may find it’s still difficult to reach your daily fat goal. If you are struggling, you can try a supplement like MCT oil.

Be careful, once you’ve entered ketosis you can still kick yourself out by eating too many carbs. If you do this then you will likely experience the keto flu all over again when lowering your carb intake back down. It is always better to be on the safe side and limit your carbs to about 20 grams per day.

Don’t Give Up

If you are suffering from keto flu symptoms, remember that there is a light at the end of the tunnel.

As soon as you push through the adjustment period, your body will begin to lose fat and you will start to feel more energetic and alert.

Remember that these benefits are worth a couple of days of feeling under the weather!

If you want to give up because of these symptoms: drink some water, eat some fat, supplement your electrolytes, and I promise you’ll be ready to continue pushing forward.

Planning for the Keto Flu

The best way to defeat the keto flu is to be prepared. Plan your meals ahead of time to ensure you’re eating enough fats, sodium, magnesium, and potassium. If you’re not getting enough of these nutrients in your diet then don’t be afraid to use supplements instead.

Once you’ve come out the other side, make sure you’re not eating too many carbs or you might have to suffer through the keto flu all over again.

If you follow these rules then the keto flu will be over before you know it, and you’ll be on your way to a healthier life!

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