Why You Are Tired on Keto – And What to Do

The keto diet is a newer trend that has proved to be more than a fad. People everywhere are trying the keto diet and losing weight as well as having more energy. Maybe you too have decided to try keto, but the results were not what you expected. Instead of feeling better, you feel exhausted and ill. What is going on? Does this mean keto isn’t for you?

Experiencing exhaustion is normal when starting the keto diet. Keto makes your body switch energy sources and causes an adaptation period that can leave you feeling tired. Most of the time this goes away on its own, but there are also steps you can take to feel better faster such as upping your salt and fat intake.

It can be incredibly frustrating when a diet that is supposed to leave you feeling better than ever does the exact opposite. Keep reading to learn what exactly is happening in your body on a keto diet, why this leads to exhaustion, and what you can do about it.

Why Am I Exhausted on the Keto Diet?

You were expecting weight loss, energy, and feeling like your best self. Instead, you don’t want to get out of bed. What’s going on with this new keto diet?

Experiencing exhaustion when you start keto is quite normal, but to understand precisely why that is, we need to take a closer look at what the keto diet is and what it does to your body.

What Is Keto?

Keto is a strict eating system that focuses on intensely lowering carb intake while raising fat consumption. This diet is primarily used for weight loss but has also been shown to reduce inflammation, improve brain health, and help prevent some diseases.

The keto diet works by forcing your body into a process called ketosis. Normally your body burns carbs for energy, but if there are not enough carbs your body will instead burn fat to make ketones. These ketones can then be used for energy. Ketosis is the state in which your body is burning fat instead of burning carbs.

You lose weight when your body is in ketosis because your body is burning your fat stores. This is what makes it such an effective diet for many people. Ketosis is the key to keto, but getting your body into ketosis is not an instant process.

What Happens When Your Body Transitions to Ketosis?

As we have said, ketosis occurs when your body switches from burning carbs and glucose for energy to burning fat and making ketones. However, getting your body into ketosis is a bit of a process.

Your body naturally burns carbohydrates first. That is its default setting. It will only turn to burn fat when there are not enough carbohydrates to provide the necessary energy for your body to function.

What does this mean? When you start a keto diet, your body’s energy source (carbs) is suddenly massively depleted, and it needs time to adapt to using the new source (fats) effectively. The exhaustion and discomfort that come with this adjustment period are so common that it has become known as the keto flu.

The Keto Flu

The keto flu is a name given to the uncomfortable process of having your body adjust to a ketogenic diet. This adaptation period comes with several flu-like side effects including

  • Fatigue
  • Dizziness
  • Irritability
  • Nausea
  • Difficulty concentrating

The keto flu is the primary cause of exhaustion with the keto diet, and luckily, it is only temporary. Most people come out of the keto flu with even more energy than they had before now that their body is burning fat for energy.

Everyone is different, so the keto flu can vary in severity, exact symptoms, and duration from person to person. The majority of people experience the keto flu during the first one to two weeks of a keto diet, and it only lasts a few days. However, there have been cases of the keto flu lasting for a month after starting the diet.

There’s no need to panic! Even if your body is taking longer to adjust than some, you do not have to suffer from the keto flu. Several easy adjustments will halt the unpleasant side effects of switching to a ketogenic diet. However, before we dive into how to stop feeling tired on keto, let’s look at a few more reasons keto might be making you tired.


Hypoglycemia occurs when your body does not have enough sugar in the bloodstream. It leads to symptoms such as

  • Shakiness
  • Lightheadedness
  • Fatigue
  • Sweating
  • Nausea

Hypoglycemia can sometimes occur as a side effect of the Keto diet, and it makes perfect sense when you think about it. In lowering the carbs you eat, you are taking away your body’s energy source. Before turning to fat, you will first burn your glucose stores, and once this is gone your body goes into ketosis and begins burning fat to make ketones for energy.

Thus the period before ketosis often leads to lower blood sugar and sometimes hypoglycemia as your body burns through your glucose stores before turning to fat.

Does this mean that you are constantly at risk for hypoglycemia while in ketosis? No, because your body will eventually realize what’s going on. Once your body begins producing ketones for energy, it will restore your glycogen levels by using a process called gluconeogenesis, which gets glucose for protein.


If you are tired on a keto diet, you may be suffering from dehydration. Here’s why.

When you eat carbs your body breaks them down into sugars, which enter your bloodstream. Your body then releases insulin which works to keep your blood sugar levels from getting too high. On a keto diet, you are not eating carbs, which means you are not putting more sugar into your bloodstream, and your body does not produce extra insulin.

However, insulin has another job too. It tells your kidneys what to do, specifically what to hold onto. With less insulin, your body will lose a lot more water and electrolytes. This is why many people find they have to urinate a lot more on keto.

Those water and electrolytes are important for your body. If their levels are insufficient you will suffer from sluggishness, fogginess, and other problems.

Insufficient Calorie Intake

It is possible to eat so little on keto that you feel fatigued, and this happens more often than you might think. Why?

A ketogenic diet suppresses your hunger. The hunger signals your body sends when burning fat are not nearly as strong as the signals it sends when you are burning carbs and sugar. The irritability and cravings many of us experience, when we are hungry, are drastically reduced on keto.

This means that if you are following the policy of only eating when you are hungry on keto, you may not be eating enough. Of course, eating fewer calories is key to weight loss, but undereating to an extreme will leave you with no energy and can have even worse effects over time.

Not All Keto Food Is Created Equal

Just because you are eating keto does not necessarily mean that you are eating healthy. If you are eating nothing but processed food all the time, you are not going to feel good even if you are technically maintaining the keto diet.

Your Keto Diet Isn’t Keto Enough

The purpose of the keto diet is to restrict carbs enough to get your body to switch to ketosis. However, just how much restriction is enough varies from person to person.

Some people will enter ketosis if they eat less than 50g of carbs a day while others have to reduce their carb intake to less than 20g a day.

If you are living with a low carb intake, but it isn’t quite enough to push your body to start ketosis then you are essentially operating with a very limited amount of fuel. You may need to lower your daily carbs even more (be stricter with your keto diet) to get your body to make the transition and have access to the energy from fat.

Does Keto Make You Weaker?

Along with general fatigue, some people on keto also experience muscle weakness and tire more easily when doing physical activity. This can leave you with the impression that your new diet is making you weaker, but is this really the case?

Most of the exhaustion and weakness that come with the keto diet occur during the transition period. Thus it is temporary and will go away once your body learns to burn fat for energy effectively. It is best to save any intense workouts until after your body has made this transition.

However, some people do continue to experience weakness on the keto diet. This may be due to a lack of protein or simply not getting enough calories overall. Remember that a ketogenic diet does reduce appetite.

Finally, though, we must say that the relationship between keto and exercise remains slightly unclear. If you are past the keto flu, eating enough protein and calories, and still experiencing weakness when you exercise, then you may need to rethink a strict keto diet. Introducing some purposeful carbs into your diet may be necessary.

This lasting weakness with the keto diet typically only occurs with people following a robust workout schedule. It is not something that happens to all people on the keto diet.

How Can You Combat Exhaustion with Keto?

Everything thus far may have you wondering why people would ever get on the keto diet. Dehydration, hypoglycemia, muscle weakness, and fatigue do not sound like a good time, but the keto diet is still wildly popular. How?

Yes, the keto diet has the potential to make you uncomfortable, but these discomforts are often temporary and, even better, can almost always be fixed with a little knowledge and a few changes.

If you are experiencing tiredness on keto, chances are you can fix the issue with one or more of the following methods.

Increase Your Salt Intake

The first thing to try that often fixes keto fatigue is upping how much salt you eat. Remember that keto means you are eating less sugar, which means that your body does not need to produce as much insulin. This has an additional effect on your kidneys so that they do not keep as many electrolytes.

This lack of electrolytes can be a major cause of keto fatigue, but adding more salt to your diet can fix this. Start by generously salting your food. If that does not work then mix a teaspoon of salt with one glass of water a day. Many people find that drinking this salted water immediately relieves their symptoms of keto fatigue.

Drink More Water

The effect on your kidneys not only causes you to lose more electrolytes but also more water in general, which can lead to dehydration and all of its nasty symptoms. The solution to this is just what you would guess: drink more water.

On keto, you may need to drink more water than you are accustomed to to stay fully hydrated. If you notice that you have been urinating more since starting keto, this is a sign that you need to up your water intake to stay hydrated and energized.

Drinking more water is the most straightforward way to stop dehydration, but don’t forget that you can get water through other drinks as well. You shouldn’t be drinking sugary beverages, but coffee, tea, and flavored waters all count towards your daily fluids goal.

Eat More Fat

When you first start keto, your body is not yet as efficient at getting energy from fat as it was at getting energy from carbs and sugar. You can make things easier on your body and lessen your fatigue by making sure that there is fat readily available with a fat-rich diet.

As time passes and your body becomes better at getting energy from fat, you may be able to reduce the amount of fat in your diet. However, it is crucial to remember that fat is your new energy source on keto! You need to give your body fuel, and that means making sure you eat plenty of fat.

Up Your Calories

Many people do not realize just how effective keto can be at reducing your overall appetite, and this can lead to unintentional malnourishment. Not only does keto reduce hunger pangs, but it also causes you to burn more calories a day on average. It is thus vital that you keep track of your calories and maintain a healthy amount.

The simplest way to up your calories is to track your calorie intake for a couple of days to determine if you are not eating enough or if what you are eating is too low in calories. You may need to eat more or add a few heartier choices to your diet. Another way to get calories up is to eat more frequently by adding in an extra meal or snack time.  

Drink Broth

One common fix to keto fatigue that addresses several issues is drinking broth every day. Broth can give you added calories, electrolytes, and needed fluids.

Bone broth is an excellent choice, especially a well-salted one. You can also use other basic broths or stocks. If you choose a low sodium broth add in a few pinches of salt to make it more effective. One to two cups a day is a simple and effective solution for many people’s keto fatigue.

Eat Well Not Just Keto

If all you are eating is processed snacks labeled keto, then you likely need a more holistic diet overhaul to get your energy back. Outside of fats and carbs, there are important nutrients that food gives you in the form of vitamins and minerals.  

Even on keto, it is crucial to eat clean food. That means eating a variety of vegetables and proteins such as meats and nuts. You should also eat a little fruit, although this will have to be limited because of the sugar.  

Get Plenty of Sleep

What you eat isn’t the only thing that can lessen the exhaustion you may feel when starting keto. There are other aspects of your health that can have an impact on how tired you feel.

Never underestimate the power of sleep. Getting adequate sleep is vital for feeling well-rested. For the average adult 7 to 8 hours is what you need to stay at your best.

Getting sleep on keto is essential beyond just the fact that sleep gives you energy. Your sleep affects your metabolism. Inadequate sleep can lead to cravings for junk food and make it harder for your body to effectively switch to ketosis. If you are exhausted on keto and only sleeping 5 hours a night, start with the sleep before you blame the diet.

Take It Easy with Exercise

Your body is under quite a bit of stress trying to transition to a new energy source on keto. If you then add to this some intense workout, it should come as no surprise when you feel weak and tired.

Being on keto does not mean you should stop exercising. In fact, not exercising at all will make you more tired in the long run. However, you should be aware when first starting a keto diet that you may need to take it easy with your workouts while your body adjusts. Once you are over the transition period you should have even more energy to tackle your exercise with.

Make the Transition More Gradual

Finally, if you have tried everything else and the keto flu is still kicking your butt and making it hard to get out of bed, then it may be a sign that you should slow things down. Your body is clearly having trouble adjusting to keto, and that is ok! You need to listen to your body and make the transition a bit more gradual.

Instead of going full keto with practically no carbs, you can start with a diet that is low carb (between 20g to 50g of carbs a day). You can then move into doing full keto on some days for a while before going with a full keto diet. In many people, this gradual approach makes things easier and lessens the impact of keto fatigue.

Are There Ever Signs that You Should Stop Keto?

As you can see, a lot of people experience keto fatigue as an initial response to the diet. It goes away with time, and you can start reaping the full benefits of keto. However, the waiting game can also be tricky. Is there a point at which tiredness means keto simply isn’t for you?

If your exhaustion lasts for more than a couple of weeks and is combined with other problems such as moodiness and nausea, then keto may not be a good idea for your system. At this point, it is best to consult your doctor.

There are also times when the keto diet is not the best idea for you currently. Remember that starting keto puts stress on your body. If you are dealing with significant stress from another source such as work, a major life change, sleep problems, or any sort of mental health issue, then adding keto on top of that may prove more harmful than helpful.

If you want to safely navigate through the initial transition to keto and manage the keto flu, then don’t start keto when your body is already down.

Some diseases can be made worse by keto. If you have an eating disorder or digestive problems keto will probably only make you feel worse. When a keto diet is persistently making you feel bad or making you not want to eat, then it is time to find something that works for you and your body.

The Biggest Takeaway: Track Your Keto Diet  

All of this may sound both overwhelming and scary. Keto is starting to sound complicated and even a little dangerous. How is the average person supposed to manage it all? Out of all of the tips and explanations this article has addressed, there is one big takeaway that can help your keto diet be successful the most: keep track of what you are doing!

From low-calorie intake to dehydration and insufficient fat, a lot of keto fatigue comes from not giving your body what it needs. Keto is a different way of fueling your body. Because it is unfamiliar, it is quite easy to err in taking care of your body when switching to such a drastically different diet.

The best way to combat this is simply to be aware. When you first start keto you should be keeping an eye on several aspects of your new diet such as

  • Calories
  • Fat Content
  • Fluids
  • Electrolytes

A lack of any of these four things as well as other basic vitamins and minerals will cause you to feel tired, so you need to know if you are getting these necessities on the keto diet. If not, you will need to make adjustments.

Once you have experience with what you need to eat on keto to feel great and stay healthy, you will not need to keep such careful records, but keeping a log or record of some sort when you first start keto can save you quite a bit of discomfort. Know what you are putting in your body, and you will know how to alter it to help you feel better if you experience fatigue.

Use Keto Strips

One way you can keep track of things better on keto is to use keto strips. Keto testing strips work like a pregnancy test. You pee on the strip and then instead of telling you if you are pregnant, it tells you if you are in ketosis.

Knowing when you are in ketosis can be helpful for several reasons:

If you have cut carbs but are not in ketosis, you are operating with low fuel which may explain your exhaustion.

If you have just started the keto diet, once you start ketosis your body should gradually adjust. If you continue to experience severe fatigue after you have been in ketosis for several weeks further problems may be the cause.

When you are in ketosis you often need to up your fluid and salt intake to prevent dehydration and replenish electrolytes.


If you are feeling unnaturally tired or weak on keto, you are not alone! Keto fatigue is a common side effect of the diet. Thankfully, it tends to be temporary, and you can stop its effects even sooner by increasing the amount of salt, water, and fats you eat and maintaining a healthy lifestyle.

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