What Is “Keto Flu”?

The “keto flu” is often associated with some related side effects that can be rather unpleasant. Many people feel symptoms of what they call “the keto flu” as they begin their diet. This can also be known as the “carb flu.” The carb flu is experienced when the body tries to readjust to a diet consisting of little to no carbohydrates and more proteins and fats. 

The symptoms you experience is your body turning from glucose for energy to burning ketones instead. Ketones are a by-product of fat breakdown and suddenly become the main fuel source when carbohydrates are not available as an energy source. Fat is considered the body’s secondary source of calories to burn when carbohydrates are unavailable.

 Considering that the keto diet generally limits carbs to less than 50 grams of net carbs a day, this drastic overall reduction in carbs can shock the body into feeling the “keto flu.” These withdrawal symptoms are similar to those that you experience when giving up caffeine or another addictive substance.

A young man holding his head with one hand and a glass of water in the other while he sits on a green couch.
“Keto flu” is a normal part of your body adjusting to a low-carb diet.

What Symptoms Do You Feel?

The “keto flu” is similar to the symptoms of the actual flu. When you begin the “keto diet,” you might literally feel symptoms similar to the regular flu. The body must flush the water and sodium out before burning it as its main source of fuel. Most people will lose about 10 lbs during the 5 days on the keto diet. Most of that weight is water, as the thyroid hormone levels will drop, and cortisol levels will increase.

Many people experience headaches, foggy brain, fatigue, irritability, nausea, difficulty sleeping, and constipation being just some of the conditions people experience when going through keto flu. Most people experience these symptoms until their body reaches ketosis or between two and seven days after cutting down on carbohydrates. In more extreme cases, these symptoms can last a couple of weeks or up to a month in length.

“Keto flu” is a normal part of your body adjusting to a low-carb diet. However, there are things that you can do to make the symptoms more minimal and ensure that you are healthy while completing your transition to a keto diet:

Keep Yourself Hydrated:

Be sure that you consume enough liquid when transitioning to a keto diet. This is particularly true of drinking enough water. It would help if you aimed for a minimum of half of your body weight in ounces of water consumed each day. For example, if you weigh 200 lbs, you should drink at least 100 oz of water a day. If you weigh 150 lbs, you should drink at least 75 oz of water daily. Hydration is essential when your body flushes out water and salt as it prepares to shed fat rather than burn carbohydrates, a source of fat.

Replace Electrolytes:

When you lose sodium and water weight as rapidly as you do when your body goes into ketosis, it can knock your electrolytes out of whack and make you feel even worse. Ensuring that you are taking a quality electrolyte supplement daily can help minimize your flu symptoms. In addition, ensuring that you are replacing your electrolytes helps your body maintain proper hydration. Other ways to balance your electrolytes include salting your foods to taste and including keto-friendly potassium-rich foods in your diet. Including dark leafy greens and avocados can help you keep your electrolytes in balance. 

Avoid Strenuous Exercise:

You can exercise while your body goes into ketosis, but avoiding strenuous exercise can help you avoid fatigue, muscle cramps, and stomach aches when you experience any “keto flu” symptoms. Lighter workouts like cycling or power walking serve you better during the keto diet. Yoga is another option for lighter exercise as you allow the new keto diet and allow your body to adapt to burning fat as your main fuel source. Lighter exercise may help your body feel more healthy and rejuvenated.

A woman laying on her side in a bed with white linens.
Getting proper rest helps smooth over the irritability that can arise during “keto flu.”

Getting Enough Sleep:

Getting proper rest is essential to help keep your body in good health while transitioning to a keto diet. Getting less than ideal sleep can make you more irritable and moody when you are switching to a keto diet and experiencing symptoms of the “keto flu.” In addition, lack of sleep causes cortisol levels to rise, which can make you even more moody and grouchy while going through the keto transition.

Eat Enough Fats (And Carbs):

In the absence of carbs, eating enough fat can help keep you craving more carbs as you feel more satisfied. Fat is your primary energy source to burn on the keto diet, so consume an adequate amount of it. Ensure that you also consume enough protein to keep your muscles able to repair themselves and fill you up. 

Consider Starting Slowly If “Keto Flu” Lingers:

If you want to reduce or avoid “keto flu” symptoms, then consider slowly phasing cabs out of your diet. Cutting down your carbohydrate intake by a predetermined amount each week can help your body adjust to the keto diet. This provides a more gentle transition into keto rather than the unpleasant side effects you may otherwise experience. The smoother transition works for many dieters better than the sudden change that shocks the body.


Properly caring for your body while you transition to a keto diet can help ease the transition symptoms. For example, consider a slow phasing out of carbs in your diet if you don’t want to experience the complete “keto flu” effects and still wish to use the keto diet to lose weight. The less miserable the transition is, the more likely someone will stick with the plan in the long run.

While the keto diet is perfectly safe for most people, please be sure to consult your healthcare provider if you have any questions about going on a keto diet. They are there to help you, and they know your medical history. They will be happy to help you determine if this is a diet that can work for you! 

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *

© 2024 just keto things - Theme by WPEnjoy · Powered by WordPress