Why Am I Exhausted On Keto Diet?

exhausted on keto

Switching to a keto diet requires the body to adapt and adjust, and one of the most common side effects is fatigue. If you’re exhausted on a keto diet, you’re not alone. In this guide, we’ll dive into the diet and explain why individuals who modify their weekly menu to reap the benefits of a keto diet may experience a period of fatigue and lethargy. 

Causes of Fatigue on Keto

Keto flu

Some people experience symptoms known as keto-flu when they change their diet. The keto flu is associated with adjusting the diet to lower carbohydrate intake. It may take some time to adjust to the dramatic reduction in carbohydrate intake, and some people develop flu-like symptoms, usually during the first week of the new diet. Symptoms include:

  • Headaches
  • Nausea
  • Tiredness
  • Fatigue and lethargy

It is common to experience these symptoms and go through a period of generally feeling uncomfortable after switching to a new diet. In the vast majority of cases, individuals do not need treatment for keto flu and they will begin to notice some relief from symptoms after a few days. 

Not Eating Enough Calories

Maybe you’ve been following a strict keto diet for a while and you keep asking yourself, “Why do I feel so exhausted on a keto diet?”

While ketosis is said to speed up your metabolism, it can also suppress your appetite. Because of this appetite suppression, it’s easy to under-eat. 

If you cut too many calories, your body may not produce enough energy hormones – leaving you feeling weak and lethargic.


Proper hydration is critical on a ketogenic diet. This is especially true in the first few weeks, as your body is in the ketosis adaptation phase and releases extra water.

Ketosis naturally depletes your body of water and can lead to dehydration, lethargy, and cravings for carbohydrates and sugar.

Intense Exercise

When it comes to keto and exercise, studies have shown mixed results. 

While many people seem to do well on keto, others run out of energy and see a drop in exercise performance and energy levels when they don’t eat carbohydrates. If you follow a strict exercise program while on keto and you find that you are low on energy, you may want to target carbohydrates to reintroduce into your diet. 

Too Much Stress

As your body adjusts to the ketogenic diet, you may find that little things start to stress you out. This is due to the fact that the diet affects your brain and nervous system as it feeds on a different form of energy. Over time, this should ease naturally and may even improve your stress levels in the long run.

Tips to Prevent Being Exhausted on the Keto Diet

It is common to experience fatigue during the first few days of a keto diet, but if you continue to feel tired, it is wise to consider taking these steps:

  • Track your calorie intake: Many people are starting to adopt a keto diet to lose weight. Reducing your calorie intake will help you shed excess weight, but the key is to avoid going too low on your daily calorie intake. If your body is not getting enough fuel and you are not eating enough, you will feel exhausted and you may be lacking in key nutrients, which will affect your health. 
  • Drink More Water: Drinking more water will help reduce the nasty side effects of mild dehydration, which can lead to headaches, brain fog, and dizziness. Water can also be a great source of energy, so it may also make you feel more energized without increasing your carbohydrate intake on a keto diet!
  • Exercise: Exercise is a great way to keep your mood and energy levels up! However, if you’re still feeling a little under the weather, remember to rest. However, if you’re still feeling a little uncomfortable, remember to take a break. Instead, perhaps opt for easier exercises, such as stretching or yoga.
  • Ditch “Dirty Keto”: Dirty keto is a way to follow keto macros, but allows for a lot of unhealthy foods. As you might imagine, eating fast food and other processed foods that qualify for keto macros can expose your body to artificial flavors, colors and other unnatural additives. Over time, it can also lead to an imbalance between omega-3 and omega-6, vitamin and mineral deficiencies, and other issues that can exacerbate your fatigue. If you’ve been following a dirty keto diet, clean up your diet and watch your fatigue diminish.
  • Consider supplements: Dehydration and switching to a low-carb diet can cause your body to lose electrolytes. If you are prone to fatigue and exhaustion, consider taking supplements. Seek expert advice before buying supplements. 

The Takeaway

A keto diet is unlikely to cause lasting fatigue, but low levels of energy may be a sign that you need to make changes or address underlying issues.

If your fatigue doesn’t go away on its own within 1-2 weeks, you may be able to reverse it by adjusting calories, macros, food choices, activities, or supplements.

Keep in mind that other things can also contribute to low energy in ketosis. You may need more sleep, better stress management, or to discuss possible medical issues with your doctor.

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