The Keto Flu: What You Should Expect

Gaining a lot of popularity for fast weight loss benefits, the ketogenic diet is taking the world by storm with many success stories.

The ketogenic diet is a low-carb, high-fat, moderate-protein diet designed as a positive method for weight loss.

There have been studies around ketosis and the ketogenic diet in general, and many scientists and doctors deem the diet safe in both the short and long term.

Although it’s been proven safe, users have reported some side effects when first starting the diet. 

Dubbed the “keto flu,” or also commonly called the carb flu, was named from the side effects that people were experiencing due to the diet.

In this article, we’ll talk about what the keto flu is, the symptoms you may experience, prevention and remedies, how long you can expect it to last, and more.

Let’s dive right in!

The Keto Flu

When first starting out on the ketogenic diet, adopters have experienced symptoms that resemble closely to Influenza. 

Since your body will be going through carbohydrate withdrawal, your body is forced to adapt to a new fuel source. 

Your body is used to burning glucose from carbohydrate intake, but the whole point of the keto diet is to completely deplete your glycogen stores.

Once this happens, your body will create and burn a new fuel source for energy called ketones. 

Ketones are made from the breakdown in fat your body needs as a backup fuel source to survive. 

When your body starts to produce ketones, you have entered into a state of ketosis or extreme fat-burning mode. 

You can get into ketosis by fasting as well. This is why you see fasting in combination with keto a lot of times for additional fat loss benefits.

Typically on a ketogenic diet, you should be consuming no more than 50 grams of carbs per day, but your body may require a lower amount. 

Ideally, it should be 5% of your daily caloric intake, but no more than 50 grams as a rule of thumb.

Reducing carbs by this much can “shock” the body causing withdrawal symptoms, especially if you have been consuming high amounts of sugar for a while.

These flu-like symptoms are the result of addiction as well as switching fuel sources. 

However, there are ways to completely bypass the keto flu or cut down the time you experience it for which we’ll get into.

Here are some symptoms you may feel.


Your body is going to need to go through adaptive changes by switching its main source of fuel. 

This is not a small change either, as you may see with the symptoms you experience.

You’ll see signs within the first few days when you cut your carbohydrate intake, and what you experience will vary from the next person.

Some people experience no side effects at all, but others have reported some of the following keto flu symptoms:

  • Aches
  • Brain fog
  • Bloating
  • Back pain
  • Blood pressure
  • Chills
  • Cough
  • Congestion
  • Constipation
  • Diarrhea
  • Dizzy
  • Exhaustion
  • Fever
  • Fatigue
  • Headache & migraines
  • Hypoglycemia 
  • Irritability
  • Insomnia
  • Indigestion
  • Joint pain
  • Loss of appetite
  • Lethargy
  • Muscle aches
  • Nausea & vomiting
  • Rash
  • Rapid heartbeat
  • Sore throat

A runny nose is not a symptom of the keto flu, although some think it is. This can be the actual flu or the common cold.

While these symptoms can be tough to initially get through, they’re usually only around for a very short amount of time. 

Don’t give up just because you’re experiencing these symptoms. 

If you’re scared or unsure, talk to your doctor and see if what you’re experiencing is normal. They will know best and take into consideration your medical history.

Yes, when starting out on keto, you may experience some unpleasant symptoms, but stick with it. It will be over shortly!

Keto Flu Prevention & Remedies

There are ways you can prevent the keto flu from rearing its ugly head, making the transition to a high-fat diet much easier.

Here are a few remedies to make you feel better and things you should do to prevent the keto flu or reduce your symptoms:

Drink Lots Of Water

Not only is it good to have a good amount of water for general health purposes, but it will also really help on the keto diet.

When you deplete your body of glycogen stores, water leaves your body through your urine, leaving you dehydrated.

Water binds to carbohydrates which is why you lose so much weight the first week of keto. It’s all water weight.

This will help muscle symptoms like cramping and if you’re experiencing diarrhea issues. It’ll replace the loss of fluid your body is eliminating. 

Strenuous Exercise Should Be Avoided

You’re probably not going to want to do anything anyway while having feelings of the flu, but some people want to power through it thinking it’ll make them feel better.

Now is definitely the time to give your body a rest while it’s trying to figure out how to best use what you’re giving it for fuel.

Light exercising is fine if you just want to move, but try to avoid heavy lifting workouts until you’re back to feeling like your old self.

Try walking, stretching, yoga, or biking to get the blood flowing if you’re itching for a workout.

Electrolytes Need To Be Replaced

Along with a loss in water, your body is also getting rid of precious electrolytes with it. 

Your body needs magnesium, sodium, calcium, and potassium if you want to start to feel normal again.

Be sure to salt your food regularly and include keto-friendly foods high in these vitamins and minerals like green leafy vegetables, avocados, and others to avoid muscle cramps, insomnia, other sleep issues, and headaches.

Get More Sleep

It’s one thing if you’re feeling insomnia as a symptom of the keto flu, and it’s another if you’re depriving your body of sleep.

Irritability and fatigue are often complained about when the body is trying to adapt to keto.

Your stress hormone, cortisol, rises when you don’t get sufficient sleep and will make you irritable and moody.

Try the following suggestions to get better rest:

  • Stop consuming caffeine at least 10 hours before bed. The best time is to keep caffeine in the morning so your body has time to get rid of it before it’s time to go to bed.
  • Get blue light-blocking sunglasses and reduce your screen time to at least an hour before bed. Blue light has been shown to impair sleep.
  • Find ways to relax like taking a bath, meditate, stretch or do some yoga. This will help you wind down, especially after a stressful day when you’re not feeling well.
  • Wake up and go to sleep at the same time each day. This helps your body get into a good rhythm, and it’ll naturally help you rise and go to sleep on a normal schedule.

Get Enough Fat In Your Diet (And Remove Carbs)

Eating fat will naturally fill you up and keep you satiated. 

Make sure you’re eating the right kinds of foods, though. You want to make sure the macro breakdown of the foods you’re consuming is right for your diet.

Remember, you should be consuming about 70% of your calories from fat, 25% from protein, and 5% from carbs.

Using fitness and calorie apps will help you dial in your daily caloric intake. Make sure you stay within the guidelines.

Remember to stay hydrated, replace your electrolytes, get sufficient sleep, rest up and consume the right foods if you want to reduce or prevent getting the keto flu.

Duration Of The Keto Flu: How Long Will It Last?

Thankfully, the keto flu does not last very long. It usually lingers for about a week for most of the people who experience it.

For others, it can last for several weeks while their bodies adapt to the ketogenic diet.

Because your body is not used to a high-fat, low-carb diet, there will most likely be an adjustment period.

It’s important to take your health very seriously. If you’re experiencing prolonged symptoms, you should reach out to your doctor to see if something else is happening.

You should not be vomiting, having diarrhea, or fever for long periods. 

However, if you follow the steps laid out above, you should feel better very soon or avoid the keto flu altogether.

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