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Home arrow Nutrition arrow Keto Diet arrow Why Am I Exhausted on the Keto Diet? Understanding the Causes

Why Am I Exhausted on the Keto Diet? Understanding the Causes

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: September 24, 2023
3 min read 1445 Views 0 Comments
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Carbs are the primary source of energy for us and when you start following keto diet your body has to adapt quickly. How long does this fatigue last?

why am i exhausted on the keto diet

If you’re on a ketogenic diet and feeling more tired than usual, you might be wondering what the exact cause of that might be. Does keto make you tired? Is there any way to fix your energy levels after starting keto?

Our experts explain everything you need to know about why starting a keto diet might make you more tired than normal and how to beat the fatigue.

Why Am I Exhausted on the Keto Diet?

Usually, to get the energy you need throughout the day, your body sources glucose from the carbohydrates you get from your food. When you eat more carbohydrates than your body can burn, that’s when your body stores them, which, in turn, causes you to gain weight.

When you switch to a keto diet, your body is deprived of carbohydrates. The basis of a keto diet is eating less than 50 grams of carbs per day, which effectively starves your body of its original energy source. This means that your body now has to start looking for a new source of energy.

This is where fat loss and burning come in. As your body searches for a new source of energy, it ends up burning stored body fat for fuel and releasing a new energy source called ketones. This metabolic state is called ketosis. However, this switch means that your body is getting less energy in-between.

You’re more likely to feel exhausted in your first few weeks of a new keto diet because your body is simply trying to find and make its new source of energy. While your body is burning fat, you’re expelling more energy.

Does Keto Make You Tired?

Feeling tired on keto isn’t as uncommon as you might think. In fact, during the early stages of the keto diet, many people feel tired and run down. Thankfully, this tired feeling doesn’t last very long. People usually feel normal again after the first few weeks.

Ketosis might also cause insomnia, that’s why you may feel even more tired.

What Is Keto Fatigue?

Most people call this phenomenon of feeling more tired than usual after starting a ketogenic diet keto fatigue, or keto flu. However, sometimes this keto flu can be caused by more than just being new to the ketogenic diet lifestyle. Here are the top reasons you might be experiencing keto flu on your keto diet.

You’re not in ketosis

If you’re lowering your carb intake but not entering into ketosis, then it’s very likely that you’re going to feel very, very tired. This can happen easily with new keto dieters. Getting your body into ketosis can be tricky if you’re new to it.

To make sure you’re helping your body get into ketosis, try going on a short fast before restarting your keto diet. This can help your body use up all of the leftover carbs. You should also restrict your carb intake to about 20 grams per day for the first week or so and make sure your fat intake is 75% of your daily calories.

You’re not eating enough calories

Fatigue can happen very quickly if you’re not eating enough calories or not eating regularly. For a ketogenic diet, your calorie deficit should only be about 500 calories in order to support weight loss. In order to have enough energy, you need to have enough calories. 

Giving yourself too much of a calorie deficit to try and encourage faster weight loss will only make you more tired and make it harder for you to lose weight in the long run. Focus on increasing protein intake, don’t forget healthy fats, and keep up your calories. You’ll feel much better!

Keto and Chronic Fatigue: 4 Ways to Deal With It

If you’re struggling to get your energy back while waiting for your body to get used to the new ketogenic diet, don’t worry – you’re definitely not alone. Our experts have come up with the best ways to up your energy levels on your new low-carb diet.

#1 Try a supplement

One great way to stay alert and energized is with a keto diet supplement. We suggest using keto supplements which help your body transition easily into ketosis and give you a boost of energy.

#2 Stay hydrated

This might seem like a no-brainer, but you’d be surprised by the number of people who don’t consume the recommended amount of water every day. If you’re struggling with fatigue, then a good way to boost your energy is by making sure you’re staying hydrated.

#3 Avoid dirty keto

“Dirty keto” is a term used to describe a keto diet that allows for fast foods and processed foods. If you’re going for a keto diet, the best way to stay energized is to eat healthy foods, fresh fruits and veggies, and whole grains.

#4 Get enough sleep

When you’re struggling with fatigue at the beginning of your keto journey, the best thing to do is be gentle with yourself. Try going to bed earlier in the evening if you can, and maybe make room for a nap if you’re able. Getting enough sleep helps significantly with this particular fatigue.

A Word From Nutritionist

High-fat and low-carb diets like keto are great for weight loss, but it can take some people a while to get used to this new form of energy intake and use. The health benefits of keto are amazing, but as long as you can muscle through the first week or two of feeling tired!

While on keto, it’s important to make sure you’re getting enough healthy fats and keeping up with your calorie intake while your body adjusts. You also want to ensure that you’re not dealing with too much stress.

All of these things can worsen fatigue or make it harder for your body to properly achieve ketosis. If you feel like your fatigue isn’t getting any better, don’t hesitate to contact your physician. Keto is great for losing weight, but it’s also not a diet for everyone!


During the adaptation phase of a new keto diet, you might feel more tired than usual. However, feeling as if you have low energy is completely natural. Many people struggle with the sudden switch from carbs to ketones, and low carbohydrate levels can cause a lot of fatigue.

In order to combat this fatigue, make sure you’re not eating too few calories, make sure you’re getting just the right amount of healthy fats, and stay hydrated. You may want to try a keto supplement to help you stay energized while your body gets used to your new low-carb diet.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: September 24, 2023
3 min read 1445 Views 0 Comments

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