We include products we think may help our readers. If you buy through links on this page, we may earn a small commission.
The complete guide to the Keto flu: what it is, how long does it lasts, symptoms, causes, and six effective tips about how to get rid of it. The Keto Diet as we have explained in more detail here, is a low carb diet and lifestyle where followers stop eating carbs and start eating fat; this starts a process called ketosis. Ketosis is where the body, starved of glucose that is provided by carbs, uses fat for fuel. A diet that burns fat can massively increase weight loss and increase overall health levels. Keto headaches are quite common so I have written a section all about Keto headaches towards the end of this article.
In the initial stages of ketosis and as a side effect of the body using ketones for energy instead of glucose, many people report flu-like symptoms. These effects are nothing to worry about, are typically short lived, and go away once your body adjusts to the new diet. It is worth noting that Keto flu is not actually like influenza and it is not at all contagious, it gets its name due to sharing some of the same symptoms. Even though symptoms are short lived they are not fun to experience. The good news is that there are things that you can do to feel better and overcome symptoms.
Yes! Any diet that is low carb can elicit Keto flu symptoms, so despite the name it is not actually unique to the Ketogenic diet and can occur in other diets like Atkins. These flu-like symptoms are caused because your body has previously exclusively used carbs as fuel. When you stop eating carbs, your body goes into shock because it does not know how to use fat as fuel. The symptoms will go away once your body enters ketosis and adjusts to using fat instead of carbs for energy.
No, Keto flu is neither related to nor not the same as ketoacidosis. The name is similar but that is where the similarity ends. Ketoacidosis is a condition where the body produces large numbers of ketone bodies which causes the blood to become more acidic. Ketoacidosis can be a life-threatening condition: people following the Ketogenic diet typically do not have ketoacidosis.
In the early stages your body needs to adapt to the change in diet of using fat rather than carbs for energy. As you can imagine, our bodies are used to converting carbs into glucose as for most of us this is how we have lived for the majority of our lives so changing this can have some effects on your body. Consequently, a body deprived of carbs will go through carb or sugar withdrawal. This is the primary cause of these flu-like symptoms. Common side effects that people new to the diet experience can include feeling fatigued or tired, headaches, stomach cramps, dizziness, and nausea. Irritability is also quite common due to craving carbs/sugar.
Symptoms typically last about a week. Around days 3 to 4 is when symptoms are usually their worst. However, duration of Keto flu is different for individuals; for some it might last a few days, for others a few weeks. It is rare for it to last longer than this. If you find that symptoms lasts longer than a week you might be eating too many carbs and not enough healthy fats, so you might need to evaluate what you are eating and reduce your carb intake further.
Below is an alphabetical list of common symptoms reported by people who have just begun the Ketogenic diet. It is worth noting that while these are commonly-reported symptoms it is rare for one person to experience all of them.
Fatigue or tiredness
Insomnia - difficulty sleeping
Lack of motivation/enthusiasm - feeling listless
Low energy levels
Muscle cramps, spasms, weakness or soreness
Nausea - feeling sick or unwell
Poor concentration - brain fog
Restlessness or irritability
Sensitivity to heat - feeling feverish
Stomach cramps - pain, bloating, constipation or diarrhoea
These symptoms don’t usually last longer than a week, but many people to give up on the diet due to how these flu-like symptoms makes them feel, which is a shame as the ketogenic diet is amazing for health and weight loss. Often people feel like there is nothing that can be done about Keto flu, but this is a mistake. There are many things that can be done to reduce symptoms. I will discuss some of the things that can be done to alleviate some of these things as I go over the key causes.
If you are currently experiencing some of these symptoms you might be wondering if there is a keto flu cure. There may not be a cure for Keto flu, but it is easy to treat with changes that you can make and the symptoms are short lived. Here are some tips about how to treat Keto flu that can help ease some of the symptoms.
When starting the ketogenic diet it is tempting to cut carbs as quickly as possible, but this is likely to make Keto flu symptoms worse. It is therefore best to start gradually to get your body accustomed to ketosis; start by gradually decreasing your carb consumption over a few weeks prior to properly starting the diet; you won't enter ketosis so you won't get the benefits of ketosis but you should prevent some of the negative affects of Keto flu. Weening yourself off sugar for a few days is also a good start. Once you are used to reduced sugar it is time to start cutting starchy foods like potatoes and rice. At the same time you should also be increasing your fat consumption to help ease your transition into ketosis. A traditional western diet is primarily based on using carbs/glucose for fuel so getting your body ready for the change from a carb-rich to a carb-restricted diet should make the transition to the ketogenic diet much easier on your body. If you are already experiencing symptoms of Keto flu one way to reduce these is to eat some carbs, this will stop you from being in ketosis but if it helps you to stay on the ketogenic diet for longer then it might be worth a day or two over your daily carb limit if this stops you from giving up on the diet entirely. Eating nutrient-rich dense foods is also beneficial, you can read more about what foods you can eat in this article.
Another common mistake that people make is not eating enough food. The ketogenic diet is about restricting carbs not restricting foods in general. Eating enough healthy fats will help reduce carb/sugar-cravings as well as giving you enough energy to combat tiredness. For beginners I recommend The Custom Keto Diet as following this diet plan will help remove the guesswork from the ketogenic diet and help you get healthier and lose weight faster.
An imbalance of electrolytes is the main cause of the Keto flu. Electrolytes are minerals that help regulate the amount of water in your body and are necessary for critical body functions such as balancing pH levels, moving nutrients into cells and removing waste from cells. Electrolytes are also critical for ensuring your nerves, muscles and brain work properly. You can probably see why an imbalance in electrolytes can have such an effect on your body, but why Keto cause an imbalance of electrolytes? Cutting carbs affects how your body produces insulin by significantly decreasing how much insulin is in your body. This is why the Ketogenic diet is often linked with diabetes. Reduced levels of insulin causes your kidneys to expel excess water and sodium/salt which in turn makes your kidneys increase production and release of calcium, magnesium, and potassium. Or to put it simply as your insulin levels decrease with ketosis, the kidneys naturally remove sodium from the body. Whereas previously there was a balance being maintained by carbs/glucose, by cutting carbs this equilibrium is shaken. This imbalance is why you get Keto flu. Insulin is also part of the process that transports glucose to the brain, therefore before the brain starts to use ketones instead of glucose for energy, which usually takes a few days, it will have less fuel. After a few days your blood glucose returns to normal levels: this does not harm your brain in anyway.
The best way to increase electrolytes is to eat more foods high in sodium/salt, magnesium, and potassium. You will find these minerals in avocados, almonds, seaweed, seeds, mushrooms, and leafy greens like spinach and kale. Also don't be afraid of adding extra salt, lots of salt is required on Keto as you are restricting carbs which are a good source of salt. It is recommended to consume around 2-3 teaspoons of salt a day when on Keto; it is best to add salt with every meal to ensure you are getting enough sodium. When on Keto you need to remove any concerns you have about sodium/salt being bad for you, your kidneys are removing a lot of salt when on Keto so you need to replenish that one way or another. Remember, low sodium is the primary reason for Keto flu! Bacon is naturally salted as are salted nuts, both excellent for helping you maintain your sodium levels. The Custom Keto Diet will also help with eating the right foods to keep you happy and healthy during Keto.
When following the Keto diet you need to drink a lot more water than you did previously. This is due to again removing carbs from your diet. When eating carbs your body stores excess water along with glucose in your liver, without carbs your body retains less water, which makes it easier for a Keto dieter to get dehydrated. Drinking more water is also one way for how to get rid of Keto headache flu symptoms: drinking at least 16 cups (about 4.5 litres) of water is recommended to help get over keto flu. In addition, in the early stages of ketosis your body rapidly burns through your stores of water; it is usually this water burning that produces the initial amazing weight loss on Keto. It is also important to note that drinking more water will make you go to the toilet more, which makes it even more important to replenish electrolytes as if you do not this will just make Keto flu symptoms worse as the increase water intake will just make your kidneys expel more electrolytes. So make sure to drink plenty of water on Keto and replenish electrolytes. These two things should be seen as two sides of the same coin. You could also try Dr. Berg's Electrolyte Formula; this helps replenish electrolytes into your body; as it is potassium-rich and 100% Keto-friendly as it does not contain carbs or sugars. As it is a powder that needs to be diluted into water, not only does it help balance electrolytes it also helps increase your water consumption.
Making the transition from a carb-rich to a carb-restricted diet can cause you to crave foods that are restricted on Keto such as sugars and carbs. If your diet has comprised of foods like bread, pizza and potatoes it is normal to crave them if you abruptly stop eating them. Eating plenty of fat, which is the primary source of fuel on Keto, should help alleviate these cravings as not feeling hungry should stop you from excessively thinking about food and more importantly stop you from thinking about foods that you used to enjoy but now can no longer eat. This tip is related to tip 1: starting Keto gradually as slowly transitioning to Keto can help you get used to eating fewer carbs while increasing fat and protein in your diet. This can also help decrease Keto flu symptoms. You can read this article which is all about what foods you can and cannot eat on Keto. Eating eggs can also help feeling fuller for longer as I have explained in this article.
During the first week or two of Keto it is best to avoid very strenuous exercise; this might interfere with your existing exercise regimen but in the long term the health and weight loss benefits will be worth it. Not exercising strenuously when you start Keto will help to reduce stomach cramps and fatigue. This doesn't mean you should stay in bed, a good tip when new to Keto is to go for a walk rather than running or cycling. When you wake up, put some water in a bottle, have a pinch of salt, and go for a brisk walk for an hour; a useful tip to know that you are not exercising too strenuously is to walk at a pace that allows you to talk without getting out of breath. This will help you lose weight and get healthier and feel better about yourself. If walking makes your Keto flu symptoms worse you might be dehydrated, low in electrolytes, or not eating enough healthy fats. Not eating enough fat can mimic Keto flu symptoms, so make sure you are not eating fewer carbs and eating less fat. Fat is the primary source of fuel on Keto so you need to eat a lot of healthy fats to give your body the nutrients it needs. Swimming or yoga are also good low intensity exercises when starting Keto to help with Keto flu symptoms. Once your body is used to Keto you should be able to resume your normal exercise regimen.
Getting plenty of sleep is important for mind and body; sleep regenerates your energy levels. Getting at least seven hours of sleep is especially important for people on Keto. When starting on Keto your body may need more sleep during the transition from carb to no-carbs. A lack of sleep raises bloodstream levels of cortisol which will only make Keto flu symptoms worse. Sleep can also help with reducing fatigue and low energy levels by helping you feel fresh and well rested. Napping can help reduce some of the Keto flu effects. Once you are in ketosis you can go back to your normal sleep routine. Tips to get more sleep include reduce caffeine (if you must drink caffeinated drinks restrict them to the morning), remove artificial lights from your bedroom routine (don't use mobile/cell phones, computers, or televisions when lying in bed), and taking a bath can help you relax and get ready for sleep.
There are a few other side effects to the ketogenic diet, and these are also often short lived. You might notice you are more itchy which might produce something called the Keto rash. You might notice some bumps and redness on your skin, typically around armpits, back, chest, neck, shoulders, and stomach. Like Keto flu, Keto rash affects different people in different ways. If it lasts longer than a week you might need to consult your physician as you may have an allergen to one of the new foods you are eating. Constipation is also quite common when starting a new diet as your body gets used to the new foods you are eating. This is not unique to Keto but it might be more prevalent on Keto as you might be easting less fibre. An easy remedy is to eat more fibre, though obviously not sources of fibre that contain carbs; avocado, nuts and seeds, and leafy greens like spinach are a great source of keto-friendly fibre.
At the start of the keto diet the change of diet from carb-enriched to fat-enriched may cause headaches and concentration difficulties. However, as I talk about above, keto headaches should be short-lived. Indeed, people following the Keto diet long-term often report better clarity and focus.
This is a question I get asked a lot. The answer is that there both is and is not a remedy for Keto headaches. Keto headaches are part of the general Keto flu symptoms that I describe above, so any of the six tips above will help cure Keto headaches. So the remedy is no different from the other remedies, there is not a specific remedy tailored towards headaches. Having said that. staying hydrated is particularly important to help with headaches. Dehydration is particularly common with Keto as when shifting to ketosis people tend to urinate more frequently, therefore headaches might be more common in the mornings when you wake up. This dehydration coupled with electrolyte imbalance will lead to headaches. A simple remedy to help with Keto headaches is therefore to drink more frequently and replenish electrolytes such as by using Dr. Berg's Electrolyte Formula.
Keto headaches are usually short-lived, like all Keto flu symptoms. Once ketosis is established headaches and other flu-like symptoms tend to go away. It is rare that headaches last as long as 2 months, 1 to 7 days is typical, if they last longer than this while other common keto flu symptoms have gone away you should consult your physician, though It is very unlikely to be anything serious. It might just need a small tweak in your diet or lifestyle, such as more sleep, less time in front of your computer, etc.
The Keto flu can make you feel bad about yourself and the Keto diet. Including a few more carbs into your diet for a day or two until you start feeling better and more able to carry on with the diet is one Keto flu remedy. Other Keto flu remedy is to keep yourself well hydrated and to cutdown any strenuous exercising for a few days. The Custom Keto Diet can help you understand the diet, help you keep in ketosis, and guide you along. Dr. Berg's Electrolyte Formula; can help replenish your electrolytes during the initial stages of Keto. Once your body has adjusted to using fat for fuel instead of carbs you should start to feel normal again. Keto is an amazing diet that can increase your health and well-being, so don’t let Keto flu, or the idea of keto flu if you haven't tried the diet yet, put you off. It is important to remember that Keto flu symptoms are short lived, affect individual people differently and are not guaranteed to affect you, so Keto flu should not put you off Keto completely.