What is the Keto Flu: How To Recognize & Remedy Keto Flu Symptoms?

While the ketogenic diet boasts incredible health benefits like rapid weight loss, increased energy levels, and cognitive clarity, many people experience fatigue, irritability, trouble sleeping and other flu-like symptoms when first starting the keto diet. It’s called the “keto flu”. In our guide to the Keto Flu, we discuss what keto flu is, why it happens, and explore some keto flu remedies like electrolyte supplements, hydration, and exercise, to help you recover quickly.

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How to recognize keto flu symptoms and cure the keto flu

You’ve decided to try the ketogenic diet because you’ve been hearing about its incredible health benefits like rapid weight loss, increased energy levels, and cognitive clarity. Instead, after a few days on the low-carb diet, you’re feeling fatigued, irritable, and you’re having trouble sleeping. If this sounds familiar, you might be suffering from the “keto flu”.

While it isn’t uncommon, the symptoms of keto flu can be severe enough to deter many people from continuing on the keto diet. If you can power through the relatively short period of discomfort, you will recover from the keto flu and experience many of the real transformative benefits of the diet.

Here, we’ll discuss what the keto flu is, why it happens, and explore some remedies like electrolyte supplements, hydration, and exercise, to help you recover quickly.

What is keto flu?

Keto flu is a group of symptoms experienced by some people during the initial stages of the ketogenic diet. It has nothing to do with the actual flu, although the symptoms can be similar.

If you’ve been eating a high-carb diet, your body is used to glucose (sugar) being its primary source of fuel. When you get on the ketogenic diet, you drastically reduce the consumption of carbs, and your body has to start burning fatty acids for energy. The metabolic state where you’re mainly reliant on fat as your fuel source is known as ketosis [1]. In ketosis, you produce something known as ketone bodies, which are responsible for many of the health benefits of the keto diet.

As you transition from being a “sugar burner” to a “fat burner”, your body has to go through some significant changes in its metabolic system. As a result, you might get stuck in a period when it’s not burning either sugar or fats efficiently, causing the symptoms of keto flu.

What are the symptoms of keto flu?

The symptoms of keto flu will vary from person to person because there are different reasons why someone might experience them. The symptoms can be mild or severe, depending on someone’s overall health and lifestyle.

You might experience one or many of the following symptoms of keto flu [2]:

  • Nauseousness
  • Digestive issues like constipation or diarrhea
  • Difficulty concentrating
  • Feeling irritable
  • Fatigue
  • Dizziness
  • Headaches
  • Trouble falling asleep
  • Increased appetite for sweets
  • Decreased sex drive
  • Muscle weakness and soreness
  • Lack of motivation to exercise

What are some causes of the keto flu?

As you make the transition from glucose to fat as your fuel source, there are a few different processes within your body that are affected, causing you to experience the keto flu.

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Electrolyte imbalance

When you eat a regular high-carb diet, your digestive system breaks the carbs down into glucose, which spikes your blood sugar. In response, your pancreas produces insulin, a hormone that helps your cells absorb the sugar from the blood to be used for energy [3].

Another function of insulin is to communicate with your kidneys and regulate how much sodium your body stores [4]. When you restrict carbs, you don’t produce as much insulin, and you start flushing out sodium and other minerals from your body.

Losing a significant amount of minerals like sodium, magnesium, potassium, etc. cause an electrolyte imbalance in your body, and result in keto flu symptoms like fatigue, lethargy, digestive disorders, irritability, and more [5]. You might also end up losing a lot of water in the process, and end up dehydrated.

Carb withdrawal

If this is the first time you’ve drastically reduced your carb consumption, it’s only natural that you’ll feel some unpleasant effects. Sugar and carbs activate the reward systems in the brain, and in their absence, you might produce less of the “feel-good” hormones [6][7]. It has been suggested that the experience of keto flu can be similar to the withdrawal from addictive substances.

Why you get Keto Flu on the Keto Diet

Also, fats are typically your “backup” source of energy that you can only tap into once you’ve drained all the glucose from your system. At the point of transition, you might go through a period when you’re not adequately burning either fats or glucose for energy, and feel fatigued and lethargic.

Decreased T3 thyroid hormones

Your carbohydrate intake has an effect on the T3 hormones produced by your thyroid gland [8]. When you eat fewer carbs, your T3 levels can fall. T3, along with another thyroid hormone T4, plays a part in regulating vital functions in your body like heart rate, body temperature, breathing, and much more. The decreased T3 and T4 levels can cause keto flu symptoms like insomnia, muscle soreness, and difficulty concentrating [9].

Hormonal stress response

The sudden decrease in glucose might signal to your body that you’re in starvation mode, and your stress response will get triggered. The stress response is your body’s “fight or flight” mode, which is associated with an elevated level of the cortisol hormone, and it can result in symptoms of the keto flu [10].

Disturbed digestion and gut microbiome

Different digestive enzymes are responsible for the digestion of carbs and fats. If you’ve been eating a predominantly carb-based diet, it will take your system some time to upregulate the production of enzymes that help in the digestion of fats.

Similarly, your gut microbiome will go through some changes as you enter ketosis. If your current gut bacteria is used to feeding on carbs, it will take some time for the bacteria that feed on fats to thrive in your gut, potentially causing some digestive issues in the meantime.

Who is at a higher risk for keto flu?

Whether you experience the keto flu at all, or to what extent if you do, depends on your metabolic flexibility, which is the body’s ability to efficiently adapt to different sources of energy, which is from carbs to fat in case of the ketogenic diet. Your metabolic flexibility is dependant on a few various factors, such as your diet before the keto diet, your overall health and lifestyle, and genetics.

If you’ve been eating a diet high in carbs, especially refined sugar and processed carbs, you’re more likely to experience keto flu symptoms. Not only is your body set up to burn sugars instead of fats, but you might also have certain nutrient deficiencies [11]. This means that you’ll have to go through more significant changes during the metabolic transition, which can contribute to keto flu symptoms. On the other hand, if you ate a healthy diet, high in fruits and vegetables, and low in refined sugar, you’re less likely to experience severe keto flu symptoms.

If you’re a generally healthy individual, and you regularly get adequate exercise and sleep, then it’s likely that you’ll only experience mild keto flu symptoms. Genetically, some people have more metabolic flexibility than others, and they are able to transition to ketosis more efficiently without too many side effects.

Research has suggested that the keto diet can be beneficial for people suffering from type 2 diabetes [12]. However, the keto flu symptoms could be worse for someone that has a metabolic disorder like diabetes, and it would be best if they were monitored by a physician as they make the transition to ketosis.

How long does keto flu last?

People typically start feeling the effects of the keto flu within 1-2 days after starting the diet, and it can last anywhere from a few days to a week. In some rare cases, the keto flu may last up to a month.

What are some ways to remedy the symptoms of keto flu?

When you started the keto diet, you were looking forward to some of its potential health benefits like abdominal weight loss, improved cholesterol levels, and it’s therapeutic effects on the brain [13]. So, it can be disheartening when you start feeling the keto flu symptoms instead. But if you stick with the diet, and give your body what it needs as it goes through the transition, you will recover from the symptoms and enjoy the benefits of the ketogenic diet.

Here are some things you can do to improve the symptoms of the keto flu.

keto flu solution #1: Stay hydrated

Dehydration can happen during the keto flu for various reasons. It can be caused due to vomiting or diarrhea, or due to the kidneys flushing out sodium because of the lower levels of insulin. Other keto flu symptoms will only get worse if you’re also dehydrated.

Sip on water throughout the day, and if you can, add some Himalayan pink salt to replace some of the electrolytes you might have lost. You can also help the hydration process by eating plenty of fruits and vegetables [14].

Another great way to stay hydrated is by drinking bone broth, which is made by boiling and simmering animal bones and connective tissue for 10 to 20 hours. In addition to providing you water from the soup, it is also a great source of electrolytes like sodium and potassium. Replenishing some of the lost electrolytes will help improve some of the keto flu symptoms like fatigue, digestive issues, and more [15].

Bone broth also has a plethora of other health benefits that might support your body as it adapts to a high-fat diet. It promotes collagen production in the body which is beneficial to gut health, and it might help alleviate some of the digestive symptoms of the keto flu [16].

keto flu solution #2: Get some exercise

Exercise may not sound like the most appealing idea when you’re suffering from the keto flu, but it can help you in a couple of different ways.

If you have any muscle weakness or soreness, gentle exercise like yoga can help you feel better [17]. Yoga can also have an “anti-stress” effect by reducing cortisol [18]. It can bring your body out of the fight-or-flight state caused by the sudden decrease in glucose from the keto diet, which is a potential cause for keto flu symptoms.

As your body continues adapting, it might not be very efficient yet in utilizing all the ketone bodies that are being produced due to the increase in fat consumption. Exercise can help you burn off any excess ketones that are circulating in your system, and improve how you feel. A light workout can also help you deplete any glycogen that’s left in your body, expediting your transition into ketosis.

It’s vital that you listen to your body when you exercise during the keto flu. If you’re feeling fatigued and dizzy, you should refrain from any high-intensity workouts till you recover.

keto flu solution #3: Relax and recover

Rest is crucial when you’re trying to combat keto flu. Not only will resting allow your body to reset, but it will also reduce cortisol levels, which can improve keto flu symptoms. There are a few different ways to give your body some quality rest.

Get some sleep – Aim for 7-9 hours of sleep when you’re going through the keto flu. One of the symptoms of keto flu is having trouble falling asleep, and there are a couple of different steps you can take to help you fall asleep.

Herbal teas have been used as natural sleep remedies for centuries around the world. Research has suggested that Chamomile tea might be able to improve sleep quality and insomnia [19]. Valerian root is another herb that is often used to treat insomnia, anxiety, and headaches, all of which can be symptoms of keto flu [20]. It is one of the most popular herbal remedies for insomnia in the United States [21].

Along with drinking tea, refrain from using your electronic devices for a period before you go to bed. Your smartphone, tablet, and laptop screens emit something called the blue light, which has a short wavelength and high level of energy. It interferes with your body’s internal clock and signals your brain to keep you alert, thus making it more difficult to fall asleep [22].

Meditate – Meditation, often called mindfulness, can be a powerful tool to reduce cortisol levels, according to research [23]. It can also help you with other keto flu symptoms like insomnia and muscle pain [24]. To get started, you can set aside some time each day, typically 15-20 minutes, to concentrate your focus on an object, a thought, or just your breath. When your mind wanders, as it naturally will, gently bring your attention back to the object of your focus.

Take an epsom salt bath – Epsom salt baths can have a few benefits for the keto flu, even beyond helping you de-stress. Epsom salt is a chemical that consists of magnesium, sulfur, and oxygen. In water, it releases magnesium and sulfate ions. You absorb the magnesium when you take a bath in it, which can help improve your electrolyte imbalance, relax your muscles, provide digestive relief, and also help you fall asleep easier [25].

Keto flu solution #4: Eat (even) more fats

When on the ketogenic diet, it is crucial that you stick to the macronutrient breakdowns that are required to adapt your body to burn fats instead of sugar. You should be getting around 75-80% of your calories from healthy fat sources, about 20% from protein, and the rest from carbs [26]. If you don’t adequately restrict your carbohydrate consumption, you won’t be able to get into ketosis, and you won’t produce enough ketone bodies that provide you with the boost in energy. Additionally, if you’re eating a low-carb diet but not low enough for ketosis, and you’re also not getting enough fuel from carbs, then you’ll feel fatigue, brain fog, and other keto flu symptoms.

You can remedy this by eating more fats. In the beginning stages, it might be helpful to measure and keep track of your fat consumption to make sure that you’re eating an adequate amount since you’ll likely have to eat a lot more than you’re typically used to eating. Increasing your fat intake will expedite the fat adaptation process, and your metabolism will adapt more quickly.

One tool that will help you make sure you’re consuming adequate fat is MyFitnessPal, which is a popular calorie tracking app. You can just add all the food you’ve eaten, and the app will show your macronutrient breakdown and total calories for the day. To track net carb intake, you can add a script to MyFitnessPal – just follow the instructions here. Tracking net carbs will help ensure that your daily macronutrient breakdowns remain within the recommendations of the ketogenic diet.

Some of the best sources of healthy fats for a ketogenic diet are coconut oil, olive oil, MCT oil, grass-fed butter or ghee, wild caught salmon, and fatty portions of grass-fed beef. MCT oil can be especially helpful when trying to speed up the fat adaptation process since they can get converted to ketone bodies quicker, which might help in improving the symptoms of the keto flu [27].

Besides eating enough fats, you also need to ensure that you’re eating enough calories, based on your weight goals and activity levels. It’s possible to eat too little, especially when you’re eliminating almost all carbs from your diet. If your calories drop below a certain level, you might end up with cravings, irritability, and find it difficult to concentrate.

Solution #5: Maintain a healthy diet

As you’re going through the fat adaptation process, significant changes are happening in your body, which can also lead to many of the keto flu symptoms. During this period, it is vital that you get the optimal nutrition that will help your body perform all the necessary functions to transition smoothly. Here are some of the foods that will provide your body with the essential nutrients that it needs.

Low-carb vegetables – Many vegetables like broccoli, dark leafy greens, brussel sprouts, and others, are very low in net carbohydrates, but they are high in fiber. So, you’ll feel and stay full for longer without going over your daily carb limits. Vegetables also contain a plethora of vitamins and minerals that will help your body function better.

Avocados – Not only are avocados a great source of healthy fats, but they are also rich in many crucial vitamins and minerals like potassium, magnesium, and more. An increase in potassium levels can help make the transition to ketosis smoother [28].

Salmon – Salmon is a keto-friendly source of protein, high-quality fats, and it has almost zero carbs. It is also an excellent source of potassium and B vitamins. Many of the B vitamins like B-12, thiamin, riboflavin, and vital for optimal energy levels, brain function, and digestive function [29].

Eggs – In addition to being one of the healthiest foods around, eggs contain a negligible amount of carbs, making it an ideal for the keto diet. Eggs promote healthy cholesterol levels and help maintain steady blood sugar levels. Make sure to eat the yolk too, since that’s where most of the nutrients are present.

Keto flu solution #6: Take an exogenous ketone supplement

ONNIT Total Keto Exogenous Ketones Supplement
Onnit Total Keto Daily helps you streamline the process of getting into Ketosis and maintaining your ketogenic diet, helping you maximize the benefits of keto while minimizing any potential uncomfortable side effects of getting there, like the dreaded keto flu!

When you’re in ketosis, your body converts fats into ketone bodies that are responsible for optimal energy levels and brain function. However, during the transition period from burning sugar to fats, you might not be producing enough ketone bodies, and you may feel fatigued and lethargic.

One way to increase ketone bodies in your system to raise energy levels and improve brain function is by taking ketone supplements, commonly known as exogenous ketones. Studies have suggested that exogenous ketones are an effective way to achieve ketosis [30]. While ketone supplements are not a replacement for the keto diet, they can be a useful temporary solution if you’re going through the keto flu.

Your body can run on three different types of ketones, namely acetoacetate, beta-hydroxybutyrate, and acetone. Most exogenous supplements are based on beta-hydroxybutyrate, since it can freely flow within your blood and is most readily available to your tissues.

We recommend Onnit Total Keto Daily if you’re looking for high quality exogenous ketones from a trusted and highly rated brand.

Solution #7: Take an electrolyte supplement

Electrolytes are nutrients that are vital for maintaining many functions in your body including muscle contraction, adequate hydration, heartbeat regulation, production of energy, and more [31]. Some of the critical electrolytes are minerals like magnesium, calcium, sodium, and potassium. If you’re deficient in any of them, you might experience irregular heartbeat, weakness, headaches, digestive issues, all of which are keto flu symptoms.

During the keto adjustment period, you might be at risk of electrolyte imbalance. The low carb intake will decrease the amount of insulin your body produces, and that might result in your kidneys to flush out some of the key minerals, causing the imbalance.

Replenishing some of the lost electrolytes will restore the balance, and improve any related keto flu symptoms. While you can get electrolytes from a healthy diet rich in high-quality proteins and leafy vegetables, at times, it might be easier to take them in a supplement form. You can supplement each mineral separately, or you can find an electrolyte supplement that combines them all. Here are some guidelines:

Magnesium – The daily recommended amount for adults is between 300-500 mg. Magnesium supplements might help you with increased energy, better mood, and prevent headaches [32].

Potassium – It is recommended that adults get around 4500 mg of potassium per day [33]. Potassium can be especially helpful during the keto flu if you’re experiencing muscle cramps, palpitations, weakness, or constipation [34].

Sodium – Sodium helps maintain some vital functions like fluid balance within the body, and it is also essential for proper nerve and muscle function. The daily recommended value is 2300 mg, but if you sweat a lot or live in hotter climates, you might need more. If you’re experiencing the keto flu, try increasing sodium intake temporarily.

Keto-friendly – Many of the electrolyte drinks are available in the market are typically sports drinks that are filled with sugar. While they might provide you with some of the minerals, they’ll kick you out of ketosis. So, make sure that the supplement you take is keto-approved, which means it has no sugar or sweeteners.

The excellent Codeage Keto Electolytes supplement meets all of these requirements and is a great way to give you a boost of electrolytes while on the keto diet, helping you avoid the keto flu.

(Sort-of) Solution #8: Increase your carb intake

If all else fails, you might need to increase your carb consumption temporarily. This could be especially true if you’re someone that is highly physically active, or if your diet was too high in processed carbs and sugars before the keto diet. If you add some carbs back into your diet, it’s vital that you add healthy complex carbohydrates like sweet potatoes, whole grains, etc. Once you get over the keto flu symptoms and feel like you’re back to normal, you can gradually start eliminating carbs from your diet again instead of all at once. As mentioned before, the MyFitnessPal app (with this added script) is a great tool to help you keep track of your macronutrient breakdown.

Can you actually ‘defeat’ the keto flu?

Research has suggested that the ketogenic diet can have some serious health benefits, and that it might help patients suffering from obesity and type 2 diabetes [35]. It can also help people lose weight, maintain optimal energy levels throughout the day, and improve brain function. However, if you have some of the risk factors discussed above, like a diet high in refined sugars, you might experience some uncomfortable symptoms at the early stages of the keto diet.

Try some of the natural remedies discussed above to fight the keto flu. You can begin with simple steps like drinking more water and getting better rest. You can also increase your consumption of healthy fats and low-carb vegetables. If that doesn’t improve your symptoms, you can try taking exogenous ketones or electrolyte supplements, or both. If you stick with the keto diet through the difficulty of the keto flu, you will recover from it, and begin experiencing some of the amazing benefits of the ketogenic diet.

Reference List

  1. ^ https://www.webmd.com/diabetes/type-1-diabetes-guide/what-is-ketosis
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  14. ^ https://www.healthline.com/nutrition/19-hydrating-foods#section12
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  16. ^ https://www.medicalnewstoday.com/articles/323903.php
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  18. ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768222/
  19. ^ https://www.ncbi.nlm.nih.gov/pubmed/29154054
  20. ^ https://ods.od.nih.gov/factsheets/Valerian-HealthProfessional/
  21. ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394901/
  22. ^ https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
  23. ^ https://www.ncbi.nlm.nih.gov/pubmed/23724462
  24. ^ https://www.healthline.com/nutrition/12-benefits-of-meditation#section11
  25. ^ https://www.healthline.com/nutrition/epsom-salt-benefits-uses#benefits
  26. ^ https://perfectketo.com/how-much-fat-should-you-eat-on-a-ketogenic-diet/
  27. ^ https://www.ncbi.nlm.nih.gov/pubmed/1245892
  28. ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC524027/
  29. ^ https://www.healthline.com/health/food-nutrition/vitamin-b-complex#benefits
  30. ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5670148/
  31. ^ https://www.healthline.com/nutrition/electrolytes#imbalance
  32. ^ https://www.healthline.com/nutrition/10-proven-magnesium-benefits#section7
  33. ^ https://health.gov/dietaryguidelines/dga2005/document/html/chapter8.htm
  34. ^ https://www.healthline.com/nutrition/potassium-deficiency-symptoms#section3
  35. ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716748/

Agnit is the lead writer for uVitals. As an avid health and fitness enthusiast, he is passionate about writing content that helps people take control of their health to live happier, more productive lives. Someday, he plans to listen to his own advice and drink less coffee.

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