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What Is Keto Flu? Plus, How to Get Rid of It

What is keto flu? - Keto Function

“Good things come to those who wait.”

… and persevere. 

While it would be nice to ditch carbs and find yourself happily reaping the benefits of ketosis when you first start the keto diet, sometimes you hit a few bumps along the way before you enter this ideal energy-boosting, fat-burning state. We call those bumps along the way “the keto flu.” 

What Is Keto Flu?

The keto flu is what keto dieters have deemed the cluster of symptoms some people experience when transitioning from a standard diet to a high-fat, low-carb ketogenic diet. These symptoms have been dubbed the “keto flu” because symptoms can sometimes mimic the flu as your body adapts to fat as its new energy source in place of carbohydrates.

Does Everyone Get the Keto Flu?

Not everyone transitioning from a standard diet to a keto diet will experience the keto flu. Some will transition painlessly into the new diet, while others will go through a minor period of uncomfortableness. For a few, they may experience a longer period. But fear not...

When Does Keto Flu Hit? How Long Does Keto Flu Last?

Keto flu symptoms (if you’re going to experience them) typically appear two to seven days after starting the diet. Symptoms generally last around a week — give or take.

Why do some people experience symptoms while others don’t? Well, it’s complicated. It could be genetics. It can depend on how many carbs you were eating before and how quickly you minimized your intake. It could be because of your unique gut microbiome. The jury is out, and more research is needed before we can draw any distinct conclusions there. All we know for certain is that some people adjust better than others… and the quality of your diet pre-keto certainly makes a difference in how drastic of a change your body must undergo.

Keto Flu Symptoms

The keto flu really looks different from person to person. No two people are likely to have the exact same reaction to a new diet. Below are some of the symptoms others have experienced when transition to a low-carb diet that you could potentially encounter yourself.

  • Nausea
  • Vomiting
  • Constipation
  • Diarrhea
  • Headache
  • Irritability
  • Fatigue/Weakness
  • Muscle cramps
  • Dizziness
  • Sore throat
  • Poor concentration
  • Stomach pain
  • Muscle cramps and soreness
  • Difficulty sleeping
  • Sugar cravings

If you’re considering trying the keto diet and are getting frightened by this long list of possible symptoms, just remember they only last a short amount of time in most cases, and you aren’t likely to experience even half of them. Surviving the keto flu is possible, and what’s on the other side of it makes this experience so worth it. If you’re in the thick of the keto flu as you’re reading this, stay strong and remember why you started in the first place. Below are some of our recommendations to fight symptoms as quickly as possible.

How to Get Rid of the Keto Flu

There are a few steps you can take to help ease any unwanted side effects of transitioning to a fat-burning state, because entering into ketosis and enjoying its long list of benefits really is worth it (and we want you to experience it!).

Stay Hydrated

Glycogen, the form of carbs stored in the body, binds to water. That means when carbs are reduced through your diet, glycogen levels decrease and water gets excreted from the body. As you can imagine, when you rapidly cut carbs out of your diet, this can cause a sharp decrease in water, which is why quick weight loss is often seen at the beginning of keto as your body sheds water weight.

While shedding a couple extra pounds may seem like a good thing, water is vital to the body, and it’s important to stay hydrated. If you’re experiencing diarrhea during the keto flu period, drinking extra water becomes even more important as that can further deplete your water levels.

Replenish Electrolytes

Through the release of water stores, low-carb diets can rid your body of essential electrolytes. Keto flu drink recipes have become popular as a way to replenish electrolytes. However, if you want a grab-and-go electrolyte option, you can find high-quality keto electrolyte capsules with trace minerals. Restoring proper electrolyte balance in the body may help alleviate muscle cramps, support healthy energy levels as well as sleep, and promote joint and digestive health.

Check Your Macros

Transitioning to a new diet can be difficult even without unwanted symptoms. You’re trying to figure out what you can and can’t eat while adapting to a new lifestyle. Sometimes, out of fear and lack of knowing what’s permitted and not, we don’t eat enough.

The scenario can go a little bit like this: It’s meal time, and you’re starting to feel the first twinges of hunger. You open up the fridge to take a look at dinner options… but you’re new to keto and find yourself left with more questions than answers. “Can I have eggs? Can I have cheese? Can I have chickpea pasta? Can I have cauliflower? What about cabbage?” Overwhelmed, you close the refrigerator door because you’re feeling stressed and defeated… and you just go hungry. 

Friends, we’re here to tell you that you don’t have to do that. First, here is a keto shopping list to help you better understand all of the nutritious keto diet foods you can eat. Second, not eating enough calories throughout the day can cause more or worse symptoms of keto flu. When in doubt, opt for enjoying more healthy fats, which can help you feel full longer and fight food cravings you may be experiencing as you work toward a fat-adapted state.

Try MCT Oil or Exogenous Ketones

One unique and versatile healthy fat we highly recommend giving a try (especially during the keto transitional phase) is MCT oil. You can consume MCT oil in liquid form or in convenient softgel capsules. MCT oil is different than other fats because it goes straight to the liver from the gut to either be used for quick energy or to be converted into ketones. [1, 2] These extra ketones may help push you into the more enjoyable stage of ketosis, while also providing you with an energy boost you may need due to sleep troubles or general fatigue.

Another way to help boost ketone levels in the body is exogenous ketones. Exogenous ketones are beta-hydroxybutyrate (BHB) ketones that are bound to a salt (usually sodium, calcium, magnesium, or potassium) to improve your body's absorption of the external ketones you consume. Exogenous ketone supplements can come in a variety of flavors, such as citrus, chocolate, and berry, making them easy and fun to work into your diet. Want to learn more about whether MCT oil or exogenous ketones are right for you? You can find out more here.

Transition Slowly

If you’re feeling very unwell and are having trouble coping, consider making a slow transition into ketosis versus going cold turkey with your carbohydrates. You can do this in two ways:

  1. Cutting out categories of carbs

To gradually reduce your carb count, you can try reducing specific types of carbs each week. For example, you may want to start by cutting out juices, soda, and other sugary drinks and move on to starches, such as breads and pastas. You can then continue on to baked goods, such as muffins, brownies, etc., followed by chips, granola bars, pretzels, candy, and other pre-packaged, carb-heavy snacks. You can finish off with cutting out healthy carbs, such as high-carb fruits and vegetables, and then miscellaneous items, such as sauces, dressings, etc. You can spread this across weeks or days depending on your ability and willingness to adapt.

  1. Reducing daily carb grams

If you’re open to counting carbs, you can take a more streamlined approach of reducing a specific amount of carb grams per day or week. Evaluate how many carbs you were eating before attempting the keto diet to establish realistic goals to achieve the appropriate keto macros.

Get Enough Sleep

As with the traditional flu, giving your body enough rest during the keto flu can help you better manage symptoms and hopefully feel well faster. While sleep can be a trouble spot in the early transitional days of the keto diet, try to rest when you can — even if it’s not deep sleep — and give your body a little break. You can also try a few simple sleep hacks like cutting out caffeine and keeping electronics out of your bedroom to promote better rest.

Skip Strenuous Exercise

In the same way, try refraining from strenuous exercise. Your body is working hard to transition into its new fat burning state… This probably isn’t the best time to hit the gym hard. Save up your energy stores to help power you through your day and fight off the keto flu symptoms you’re experiencing. If you can, though, do continue walking, yoga, meditation, light biking, and other gentle forms of movement as those may help you feel better.


All in all, more often than not, the keto flu comes on a couple days to a week after starting the ketogenic diet and goes away within a week or two of the onset of symptoms. They’re typically manageable, especially when getting proper rest, avoiding strenuous activities, staying hydrated and replenishing electrolytes, supplementing with MCT oil or exogenous ketones, and staying aware of your calorie consumption and macro counts. If by chance symptoms are too much to deal with at any given time, you can always reintroduce carbs and instead transition slowly into the keto diet instead of starting abruptly. To ensure your safety and optimal health, consult with your healthcare provider to make sure the keto diet is right for you!



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