As its name might suggest, the Keto Flu, also known as the “carb flu” is a flu-like reaction your body can have while on a ketogenic/low-carb diet (particularly in the initial few weeks).

This reaction is a natural byproduct of your facing drastically reduced carb intake and therefore switching from burning glucose to burning fat instead for energy.

The keto flu is a very real thing and can leave you experiencing some unpleasant symptoms that may last up to five weeks, but this varies from person to person.

Some of the most common symptoms include achiness, drowsiness, feeling dizzy, and irritability.

Before second-guessing your diet decisions and diving head first into a pizza pie, read on to learn how you can easily combat these nasty symptoms as well as how to avoid them altogether.

Here is what we’ll cover in this article:

Why is This Happening to Me?

If you find yourself experiencing the keto flu in all of its undesirable glory, you may have asked yourself this question: why is this happening to me?

Before learning about the best ways to ward off keto flu symptoms, it’s important to understand why it’s happening and the natural process your body is going through.

By default, our bodies burn glucose (or carbs) for energy. By opting for a low-to-zero carb diet, like keto, the body will turn to fat for energy instead.

Think of dietary fats and fatty acids as your body’s backup fuel source which is mainly utilized when there aren’t enough carbs in your diet. Ketosis is the result of your body switching from a carb-burning machine to a fat-burning machine.

A Quick Word on Ketosis

Ketosis is the natural metabolic process your body undergoes when it’s severely lacking in carbs to burn and results in an elevation of acids called ketones.[1] The premise of the keto diet is to reach ketosis and reap its bounty of benefits, the most sought-after being weight loss.

Originally observed and used to treat patients with diabetes, this metabolic process can also occur if the body lacks sufficient insulin or if the insulin is not being used correctly.[2] However, it’s important to make the distinction between ketosis and diabetic ketoacidosis, as they are not the same.

Nutritional ketosis is healthy and helps facilitate weight loss. In a 2008 study published by the American Journal of Clinical Nutrition found that a four-week ketogenic diet conducted on obese men led to an average of 12 pounds in weight loss.[3]

In a nutshell, ketosis allows your body to consume fewer calories without feeling the pangs of hunger significantly more than a regular carb diet.

How Long Will the Keto Flu Last?

As mentioned earlier in this article, how long the keto flu lasts varies from person to person, but can range anywhere from a week to a month.

It typically occurs within the first few days of nixing carbs, but isn’t necessarily guaranteed to happen. This also depends on a few factors.

How to Avoid the Keto Flu

Not everyone will experience the keto flu, and this primarily depends on what your diet was before going keto.

If you’re accustomed to eating processed foods, lots of refined sugar, and plenty of carbs, you’re much more likely to induce keto flu symptoms.

If, on the other hand, you’re coming from a diet low in processed sugars and starches, the transition to a keto diet will be much easier and you’re likely to not experience the keto flu at all.

While it’s said that some people are naturally “metabolically flexible,” meaning they can easily shift metabolic states without experiencing symptoms, it’s still always a good idea to think about easing into a keto diet rather than cutting off sugars and carbs cold turkey. Just some food for thought!

How to Battle the Keto Flu

If you’re reading this article, maybe you’re already in the throes of a full-on keto flu, or maybe you just started your keto journey and want to prepare. Luckily, there are many ways to remedy keto flu symptoms, so fear not.

1. Hydrate

Water makes up roughly 60% of our bodies and when first undergoing a keto diet, the low-carb nature of it leads to more water loss. This leads to dehydration which is one of the culprits for experiencing keto flu symptoms.

Hydration is key! Just like when you have the regular ‘ol flu, you want to make sure you’re sufficiently hydrated and getting plenty of electrolytes. This will greatly help relieve your symptoms and boost energy levels.

2. Take an Electrolyte Supplement

Any low-carb diet will leave your body deficient in electrolytes since these diets tend to shun natural micro-nutrient sources, such as vegetables and starchy fruits.

This can lead to irritability, fatigue, dizziness, and a lack of focus.[3]

One way to help remedy this without cheating on your diet is to take an electrolyte supplement once per day.

If you have a very active lifestyle that includes exercise, you can also take a supplement after a workout to prevent dehydration and muscle cramps.

Just make sure your electrolyte supplement doesn’t contain artificial sweeteners nor sugar. The key ingredients to look for are potassium, sodium, calcium, and magnesium.

These are all the major electrolytes your bodies need to function properly.

3. Eat More Fats

When your carb cravings start to kick in, trick your body by ramping up your fat consumption.

This can also help speed up the transition your body is making from burning glucose to burning fat for energy.

Try adding a tablespoon of coconut or MCT oil to your coffee or tea, snack on some fatty bacon or an avocado, or boil up some delicious eggs before lapsing further into your pizza and pasta fantasies.

4. Take an Exogenous Supplement

Exogenous supplements are ketones your body takes externally, and typically come in pill or drink mix form. These beta-hydroxybutyrate supplements help ward off fatigue and can boost energy levels by increasing the ketone levels in your blood.[4]

Warning! Be sure to look for a premium exogenous supplement worth its weight in salt. This means it contains zero carbs, is naturally flavored, and only uses the highest-quality goBHB salts.

5. Light Exercise

The last thing on your mind when falling victim to the flu may be exercise, but pushing yourself to engage in light exercise, such as a yoga class or walk around the block, can actually help release endorphins that will boost your mood. It can also help relieve muscle pain and tension.

6. Sleep!

Getting plenty of sleep is another excellent remedy for stifling keto flu symptoms. You might be thinking this is a catch 22—for how can you possibly get sleep when you have the flu?

Here are some great tips to get you catching more ZZZs and therefore bringing some relief to your symptoms:

  • Drink sleepytime tea, which is a keto friendly herbal tea that promotes drowsiness and restful sleep
  • Take a warm bath with epsom salts (magnesium) to soothe and relax your muscles. This can be found at most grocery stores.
  • Try to avoid screen time (cell phones, TV, laptops, etc) at least two hours before bed.

The best way to nip a problem at the bud is to do your research and learn more to get to the root of the issue. Now that you’re more well-versed in keto flu symptoms, cures, and how to avoid it altogether, you’re better equipped to march forward in your keto journey, unencumbered!


[1] Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: A review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. Eur J Clin Nutr. 2013; 67: 789– 796.

[2] Westman E. C., Yancy W. S., Jr., Mavropoulos J. C., Marquart M., McDuffie J. R. (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr. Metab. 5:36.

[3] Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr. 2008; 87(1):44-55.

[4] Stubbs, B. J., Cox, P. J., Evans, R. D., Santer, P., Miller, J. J., Faull, O. K., … & Clarke, K. (2017). On the metabolism of exogenous ketones in humans. Frontiers in physiology8, 848.