When you embark on the keto diet, during which you strictly adhere to consuming a low amount of carbs and a high amount of fat, there’s a small but potential chance that you may contract the keto flu, which is one of the diet’s side effects. The keto flu occurs as your body makes the adjustment to using a different source of energy than what it’s normally used to, and to a different mix of macronutrients than normal. On the keto diet, you’ll get more protein and fat and less carbs–and you’ll need time to get used to this.

Not everyone who decides to go on the keto diet will experience the keto flu. Luckily, it’s only temporary, and the symptoms you experience will fade away as soon as your body adapts to its new, fat-burning state. However, it is important for anyone who’s even considering the keto diet to understand everything they can about this potential side effect. That way, if you do contract it, you’ll understand what to do and will know about steps you can take to prevent it from happening again in the future.

What Exactly Is the Keto Flu?

The keto flu is so named because the symptoms you’ll experience are akin to symptoms of the flu. It’s temporary and concerns a group of symptoms that some people will experience as they enter the state of ketosis for the first time; in general, the keto flu tends to hit people who are new to the keto diet. Typically, the symptoms fade away on their own as your body adapts to the fat it’s using for energy.

The keto flu occurs because your body, and metabolism, need some time to adjust to getting energy from fat rather than carbs for the first time. This is completely natural, and when you begin any diet, you will experience changes. By default, your body turns to glucose, or carbohydrates, as a fuel source for energy. When you begin the keto diet and lower your intake of carbs drastically, the stores of glucose within your body will become depleted, which then forces your body to find another fuel source. The first thing it will turn to in order to gain energy is fatty acids, which you receive from consuming food that has a high amount of fat, such as avocados and fish. This switch from fuel source to a different source can cause some people to suffer from symptoms that are very like the flu.

What are the Symptoms of the Keto Flu?

Typically, the keto flu will impact beginners to the keto diet, and it occurs as people reduce their intake of carbs for the very first time. You’ll know you have the keto flu when you experience certain symptoms, such as:

  • Mental fogginess
  • Pain in your stomach
  • Confusion or dizziness
  • Nausea
  • Vomiting
  • Irritability
  • Soreness or cramping of the muscles
  • Troubling focusing or difficulty in concentration
  • Constipation or diarrhea
  • Heart palpitations
  • Cravings for sugar
  • Trouble staying asleep, and falling asleep

Any symptoms of the keto flu will usually appear during the first couple days of beginning the keto diet. How long they last and how severe they are will be different for each person who gets the keto flu. Sometimes, beginners to the diet don’t experience this side effect whatsoever, and some other people have symptoms for up to two weeks. No matter what, however, if you contract symptoms they shouldn’t last for too long and once your body adapts to getting fuel from burning fats rather than carbs, you should begin to feel better.

What Causes the Keto Flu?

Generally, four conditions lead to the development of the keto flu. They are:

  • Adapting to ketosis, or to burning fats for energy
  • The loss of electrolytes and experiencing dehydration
  • Lacking the micronutrients your body needs to function in a normal and healthy way
  • A condition of withdrawal when sugar-heavy and carb-laden foods are cut from your diet

1)Adapting to ketosis

To understand why entering ketosis may have a negative impact on your body as you take time to adjust, it’s important to first understand the way that your body derives energy from micronutrient sources. There are two basic processes for energy that your body goes through, and they are:

  • Glycolysis, during which your body derives energy from the burning of glucose
  • Beta-oxidation, during which your body derives energy from the burning of fat

As your body adapts to the keto diet, this means that your body is also adjusting to the beta-oxidation process, and it’s getting used to deriving energy from the burning of fat. The term “metabolic flexibility” refers to the ability to go between the burning of fat and the burning of glucose. People who don’t have as much metabolic flexibility typically contract symptoms of the keto flu more easily, as their body gets used to burning fat to get energy. The flexibility varies from person to person, and isn’t necessarily something you have control or say over. Genetics also have a hand in your metabolic flexibility; some people have the natural ability to handle the switch of energy very easily.

The takeaway in the end is that the most significant cause of the keto flu is adaptation to ketosis.

2)An imbalance of electrolytes

When people switch diets, they often temporarily lose nutrients that they didn’t realize their old diet was providing, and the body may experience certain imbalances as it adjusts to the new food and sources of energy. The SAD, or Standard American Diet, involves a lot of foods that are processed and high in carbs; some people may not even realize this until they cut out these foods, and this is an intense switch that leads to a long period of adjustment. One of the things that often occurs during this period during the keto diet is that you’ll experience a fast loss of water, which leads to an imbalance in electrolytes.

This happens because all of the glucose that has been stored within your body due to your diet that’s high in carbs, is attached to the water within the body; every 2-3 grams of water tends to have one gram of glycogen. When you start a keto diet, your body consumes all the glycogen very quickly, which means that the water it’s bound to is flushed out of the body. As this occurs, you lose both electrolytes that are very important, and fluids. This leads to an imbalance in electrolytes, and dehydration. Together, these two states can lead to the symptoms that are akin to the flu, and these symptoms will stay until you are hydrated and replenished with electrolytes again.

As you start the keto diet and your body adapts to burning fat for fuel, it’s very important during this time to ensure you are hydrated and have plenty of electrolytes by drinking a lot of water, probably more than what you normally would. It’s also important to make sure all the minerals that you use (such as magnesium, potassium, and sodium) are put back into your body during the transition period. This will make the transition as easy as possible, and will put a steady amount of nutrients into your body that it needs. Drinking excess amounts of water and making sure you get electrolytes is a great way to help prevent contracting the keto flu in the first place, and to reduce the severity of symptoms once you do have it.

The takeaway in the end is that as you adjust to ketosis, your body will lose a lot of electrolytes and water, which can then lead to the keto flu.

3)An absence of adequate micronutrients

Another common mistake that many people who are new to the keto diet accidentally undergo, is that they forget to make sure they continue to receive an adequate amount of micronutrients from the food they consume on their new diet. The keto diet requires that you take out grains, fruits, and vegetables from your diets (except for very specific fruits and vegetables), so you’ll need to get the micronutrients you normally would from those foods, from the new foods that are keto approved.

This might require eating certain things, or consuming a lot of keto foods at first as you make the transition. For example, if you begin the keto diet and suddenly cut out all carbs as you begin to eat lots of eggs and cheese, you’ll probably end up suffering from a deficiency of nutrients. In order to prevent this from happening, it’s very important that you consume a wide variety of foods that are keto approved, yet rich in nutrients, such as meats, oils, and berries on top of all those eggs and cheese. This way, you can stay well and healthy as you make the transition to keto. What will help you is a diet that involves high consumptions of foods such as:

  • Meat that is grass-fed and comprised of cuts that are fatty rather than lean
  • Butter made from cacao and coconut
  • Avocado, coconut, and olive oil
  • Seeds and nuts (as well as butters that are made from seeds and nuts, such as almond butter)
  • Shellfish, poultry, and fish
  • Dairy that is whole/full-fat, and organic
  • Veggies such as broccoli, alfalfa sprouts, olives, cabbage, cucumber, swiss chard, asparagus, spinach, eggplant, brussel sprouts, spaghetti squash, and cauliflower

You can easily find all of these foods at your local grocery store; all of it is accessible, and easy for people who are beginning the keto diet to consume. If you are constantly on the go or don’t have much time, getting an adequate amount of nutrients through the use of supplements is a great and easy option as well. This way, no one misses out on the minerals and vitamins their body really needs, no matter what.

For example, you can get micronutrients from products such as the Perfect Keto Micronutrient Powder, which is full of nutrition that’s pure and sourced from plants. The nutrition of this powder is provided by 26 vegetables and fruits; this way, you’ll receive a healthy dosage of the micronutrients your body needs, and won’t have to physically consume up to 30 foods that are healthy and contain these nutrients. The powder also doesn’t have any fillers, additives, or sugar, so you won’t need to become worried about the inclusion of harmful ingredients that could force you from your ketosis state.

Speaking of, you need to avoid consuming specific foods as you’re on the keto diet, and you also need to take care to read ingredients lists and be very aware that some chemicals included in a lot of supplements and packaged foods may be harmful to your ketosis goals. These chemicals and foods could potentially wreak havoc (which is difficult if you consume them unknowingly), and can keep you from not only being able to reach, but also being able to maintain ketosis. These could also worsen the symptoms of keto flu and make them last longer. Foods and chemicals that have a negative impact include:

  • Grains such as oats, barley, wheat, rice, quinoa, buckwheat, sprouted grains, and rye
  • Beans such as black, kidney, pinto, chickpeas, and lima
  • Many fruits, including ones that are tropical such as oranges, pineapples, mangoes, bananas, and papayas, as well as grapes and apples
  • Vegetables that are starchy, such as carrots, potatoes, corn, parsnips, and sweet potatoes
  • Sugar that includes raw sugar, high fructose corn syrup, and cane sugar; also sugars that are very sweet, such as maple syrup, agave, and honey
  • Milk and other dairy that is low in fat
  • Meat that’s very conventional and farmed in factories, like meats that are grain fed, fish that are raised on farms, and hot dogs
  • Oils that are made from vegetables, such as corn, canola, soybean, peanut, sunflower, safflower, sesame, and grapeseed
  • Sweeteners that are artificial
  • Sweetened/sugary beverages
  • Alcoholic beverages
  • Foods that are heavily processed

The takeaway in the end is, deficiencies in micronutrients can lead to the keto flu, and can worsen symptoms or prolong the existence of the flu once you get it. The key to preventing the flu and to lessening its symptoms is continuing to receive the nutrients you need as you begin the keto diet.

4)A withdrawal from carbohydrates

Research has indicated that the way sugar impacts the brain is very similar to cocaine and heroin, which are two substances which are very addictive. Our brains do find pleasure when we consume sugar, and our system receives a dose of dopamine, the hormone that makes you feel good. Foods that contain a lot of sugar also are naturally addictive, and this won’t help you as you embark on the keto diet; this is why a withdrawal from carbs is a leading cause of the keto flu.

You’ll see this manifest as:

  • Mood swings
  • Intense sugar cravings
  • Irritability
  • Nausea and other flu-like symptoms

These feelings will be especially intense in those who previously consumed more refined and processed sugars and carbs than normal people. If you fall into this category, you’ll also find a lot of trouble as you adapt to a state of burning fat for energy instead of carbs. However, if you experience this, it doesn’t necessarily mean that you should give up. If you have these negative symptoms of withdrawal, keep faith that it’s merely a sign that you’re closer to achieving ketosis, and all you need to do is keep going. At this point, when there are indications that your body is struggling, you’ll tip over and the benefits of keto will finally begin to make an impact. Once all of the carbs and sugar are kicked out of your body, you’ll understand why the discomfort will be worth it in the end.

The takeaway in the end is, a withdrawal from carbs can worsen any symptoms of the keto flu that you are feeling. This is especially true for people who used to consuming a lot of processed carbs, sugars, and other unhealthy foods.

Five Steps to Rid Yourself of the Keto Flu

If you realize you already have the keto flu, you can rest easy knowing that it won’t last for very long. There are also steps you can take to reduce your symptoms, or even get rid of them completely, as you make your transition into ketosis. If you think you’ve contracted the keto flu, and you’re already experiencing symptoms so there’s no way to prevent it, you can:

  • Ensure you’re hydrated. Drinking more fluids than what you normally would should be one of your biggest goals as you start the keto diet. The loss of water that happens as you start should be replenished, and if you do so, the transition will be easier. You should consume lots of water through the day to prevent fatigue and headaches, and you can do this easily by:
    • Using a water bottle and drinking several bottles worth throughout the day
    • Try to prevent yourself from feeling thirsty
    • Consume most of the water during the day, not at night
  • Ensure your electrolytes are replenished. As you drink lots of water, your focus should also be on receiving electrolytes so they’re rebalanced. Before this, you might not have even thought of electrolytes, unless you’re an athlete or are trying to recover from a hangover. However, the transition into keto will take electrolytes from you just like these other situations, so you need to replenish them. Keep this in mind to help:
    • Increase your intake of sodium. This’ll go against the loss of water that occurs as you begin keto. You can take supplements, or ensure you eat foods high in sodium.
    • Take magnesium supplements. It’s very important to have this mineral in your regular diet anyways, because a low level of it can cause resistance to insulin and depression. Eat salmon, dark chocolate, avocado, cashews, pumpkin seeds, and spinach to get your magnesium.
    • Eat foods that are keto approved and rich in potassium, which is another important mineral you should be consuming. Potassium will help you control your bladder, regulate the temperature of your body, regulate your heartbeat, and have energy. You should eat foods that have lots of potassium, including zucchini, brussel sprouts, avocado, pumpkin seeds, and mushrooms as you’re on the keto diet.
    • Eat foods that have lots of calcium. Not only does calcium help with bone health, it also aids with muscle contractions, your heart beat, and the clotting of your blood. You can eat salmon, chia seeds, sardines, leafy greens, and broccoli.  
    • Consume bone broth, which does great things for your skin and keeps you hydrated as it delivers potassium and sodium.
    • Take supplements for electrolytes. These supplements are designed to provide instant relief and give you electrolytes more quickly than food.
  • Ensure you’re completing an adequate amount of exercise. The exact kind of exercise you do does make an impact as you transition into keto and begin to burn fat instead of carbs. You should do light exercise and focus on aerobics that are low in intensity, such as swimming, yoga, and walking. As you begin keto, you might have a tougher time at first exercising as your body adapts to its new fuel burning state.
    • While you may have difficulties during this, you shouldn’t laze around either. You need to continue to get light exercise at least twice a week. This will help your body adapt and make it increase in efficiency. It’ll also help your metabolic flexibility, and if you have symptoms of the keto flu, they’ll decrease faster. Once you reach ketosis and complete the transformation, you can get back to how you exercise normally.
  • Make sure that you increase your fat intake. Since you’re not receiving energy from sugars or carbs any longer, you’ll need to supplement this loss with a lot of protein and fat so your body can still get the fuel it needs. You need to ensure that all the carbs you used to eat, are now replaced with fats that are keto approved. These include:
    • Coconut oil
    • MCT oil
    • Palm oil
    • Eggs
    • Cacao butter
    • Heavy cream
    • Ghee, or butter that’s grass fed
    • Fish that’s fatty
    • Avocado oil
    • Avocados
    • Fat from geese
    • Fat from bacon and lard
    • Extra virgin olive oil
    • Chia seeds, flax seeds, and sesame
    • Walnuts, pecans, and macadamias

Making these fats that are healthy an addition to your diet as you lower your carb intake can make your transition much easier, as you’ll be supplementing your body with a lot of fats that it can use for energy. Using MCT Oil supplements can also reduce the symptoms of the keto flu you’re experiencing, because it helps to increase your levels of ketone, and this can make the period of transition shorter. If you discover that your symptoms are lasting longer than seven days, take another look at the macronutrients you’re consuming, because you still might be consuming a lot of carbs and a low amount of fats that are healthy. Sometimes, people believe they’re making the keto transition, but really carbs they don’t realize they’re consuming are preventing them from ketosis. In the end, you need to lower your carbs and get a lot of foods that are keto approved as you start the keto diet.

  • Take ketones that are exogenous. A main reason why you’ve contracted the keto flu is the fact that your body’s struggling to adapt to keto, and all this means is that you need to create and use ketones as an energy source. You can help yourself to more quickly become adapted to keto by adding exogenous ketones, also known as ketone salts, to the routine you perform in the morning. These molecules of energy are like the bodies of ketone that your body will naturally produce, they’re just in the form of supplements. Through supplements, you can put a lot of ketones into your system and your body will be adapted to fats and adjusted to ketosis more quickly. Exogenous ketones are great to use either as you’re transitioning for the first time, or whenever you find yourself thrown out of ketosis.

Three Steps to Help Prevent Getting the Keto Flu

If you’re a beginner to keto and you’d like to prevent yourself from every getting the flu in the first place, you can follow these guidelines to avoid it easily:

  • Stick to a diet that’s keto approved yet nutritious. A big reason why people who are new to keto contract the keto flu and don’t feel good is because they aren’t careful about consuming the right micronutrients. Although you’re dieting, you need to still take care of yourself and know it doesn’t only concern macronutrients. Otherwise, you’ll end up having a deficiency of nutrients, which is a leading cause for the keto flu. A key aspect to completing the keto transition successfully without getting the flu, is to start off on a healthy diet that has keto foods, but still covers the nutritional bases. As you get used to keto, things will improve overall as well. Another important factor is that you make sure you avoid foods that are unhealthy and which will increase your levels of insulin and blood sugar, which will lead to you getting kicked out of ketosis.
  • Get lots of sleep. You should receive, at minimum, seven hours each night for sleeping. This is important in general for everyone, but it’s especially important for people who are beginning the keto diet. The metabolism in your body will need time to get used to the switch of sources of fuel, and the best time to adapt is as you’re sleeping. This can also decrease any fatigue and stress you may feel. If you can’t get seven hours of sleep each night, try napping throughout the day so you still hit the number. This will help your body handle the process of keto much more easily.
  • Take supplements that are adequate. A very easy way to avoid any side effects as you begin your keto journey is to consume the correct supplements right from the beginning. A keto diet is focused on whole foods that are very healthy, however supplements will fill any gaps in your nutrition and can ease the process as a whole. You can take:
    • Exogenous Ketone Base to enter a ketosis state more quickly
    • Electrolyte supplements to give your electrolytes a balance
    • MCT Oil Powder for more production of ketones
    • A Micronutrient Greens supplement so you get all the micros you need

Steps to Take to Get Rid of the Keto Flu Right Away

The keto diet can give you an improvement to your weight, health, and how you’re feeling, but it can be discouraging when you contract the keto flu, and you may be interested in getting rid of it as quickly as possible. If you’ve already contracted the keto flu, you can:

  • Consume lots of water
  • Rebalance your electrolytes
  • Consume bone broth
  • Up your intake of fats that are high quality
  • Keep doing light exercise
  • Take exogenous ketones to help you go into ketosis more quickly

If you have started the keto diet but haven’t felt the keto flu yet, and you want to make sure you don’t get it, you can:

  • Ensure you’re consuming a diet that’s healthy, well rounded, and keto approved
  • Don’t eat foods that may force you to fall out of ketosis
  • Get enough sleep to help your body make this adaptation
  • Be strategic about your supplement intake, so you support your transition and the changes to keep the keto flu away


Overall, as you begin your keto journey, you need to take care of your body and yourself, and practice patience. You can use all of the tips in this article as a guide to either keep yourself from experiencing keto flu in the first place, or to reduce your symptoms if you do contract it. Either way, be aware that the keto flu is very temporary, and if you’re patient, the symptoms will fade naturally. Once this difficult step is done with, you can enter ketosis and experience all the benefits that the keto diet has to offer.

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