Why Am I So Tired on Ketogenic Diet? The Reasons May Surprise You!

Everyone’s been raving about the fantastic effects of the keto diet—your friends, their friends, celebrities, athletes, and even the health experts!

After reading and researching it, you finally gave it a try.

After all, the keto diet is said to increase your focus, mental clarity, and energy levels in addition to helping you lose weight.

With this diet, nothing can go wrong, right?


A few days after switching to keto, you find yourself tired all the time. And you feel like this is probably the most tired you’ve ever been in your life.

All these unwanted symptoms you’re feeling will surely make you question if you’re doing this keto thing right. Worse, you may now be wondering if this is the right diet for you.

Here’s what we want you to know.

Fatigue is common in the ketogenic diet.

That sucks, we know. But wait, there’s more.

There are plenty of ways on how you can overcome fatigue on keto!

But before you can do that, you need to identify what’s causing it.

Here’s the good news.

You’ll find everything you need to know about keto fatigue causes in this article—including how to improve all of them!

What is Ketosis?

Ketosis is a natural part of the metabolism which occurs when the body consumes too little carbohydrates (which is the case with ketosis) or when you haven’t eaten for prolonged periods.

When the body’s not getting enough carbohydrates, insulin levels will fall, then the body releases fats.

Once the released fats enter the liver, a significant portion of these will be converted into ketones.

During ketosis, the body uses ketones as its energy source instead of carbohydrates.

However, the energy source shift can lead to plenty of side effects since your body is not fully adapted to the new energy source.

Can Ketosis Make You Tired?

Yes, ketosis can make you feel tired.

Getting exhausted on keto is a pretty normal thing. 

It’s one of the side effects you will experience during the earlier phase when you first switch to this diet.

Fatigue or tiredness is one of the most common symptoms of keto flu. This term refers to the wide range of unwanted symptoms people feel when they started the keto diet.

While these symptoms don’t indicate that you’ve come down with the flu, it is called as such because all the side effects you’re feeling are similar to flu symptoms.

Aside from keto fatigue, other symptoms of keto flu are:

While these symptoms seem dreadful, you’ll be happy to know that these usually go away after a few weeks or months once your body is already keto-adapted.

What is Keto Fatigue and Why It Happens

There are many reasons why you’re experiencing lower energy levels on a ketogenic diet.

If you wish to figure out how you can get more energy while on the keto diet, the first thing you need to do is pinpoint what causes it.

Lucky for you, we’re here to help you out! 

Below are some of the common causes of fatigue on a keto diet:

Keto Adaptation Phase

The most common reason for your low energy levels is the keto-adaptation phase.

We’re referring to the phenomenon wherein your body is undergoing an adjustment period. It’s slowly adapting to the changes in energy sources—from carbs to fats.

You see, your glycogen stores have to be depleted first before you the body starts using fats instead of glucose as its energy source. However, the process of reaching ketosis isn’t as smooth sailing as you may expect.

During this process, you will undergo lots of symptoms, which is collectively known as keto flu.

The most common symptom would be ketogenic fatigue.

How long does keto fatigue last?

To be honest, there’s no straightforward answer to this since the length of time for the keto-adaptation to occur varies from one person to another. (1)

The process starts within the first few days you begin with your keto diet. After about 7 to 10 days, most dieters will already start to see improvements in their energy levels.

Usually, the body is done with most of the work by week 3. You’ll start to experience the mental clarity and high energy that the keto diet is known for during this time.

The body will still undergo minor changes throughout your diet. Still, it’s no longer as severe as the keto flu symptoms you initially experienced. It’s around week 12 that most people would fully reach ketosis.

Mild Dehydration

Did you notice that you frequently pee the first few weeks you started on keto?

That’s another common ketosis flu symptom.

This is a sign that your body is beginning to go through your glycogen stores.

You see, glycogen molecules are highly hydrated as they are attached to three to four water molecules (2).

As your body burns through your glycogen stores, the water molecules are released. You expel the released water molecules through peeing.

While this may mean that your diet is working, it may put you at risk for dehydration.

That’s why you may not feel that good as of the moment.

Mineral Depletion

When you expel water, essential minerals tend to come with it.

These minerals may include potassium, magnesium, and sodium. All of these minerals play a crucial role in primary bodily functions.

For one, Magnesium is a cofactor in more than 300 enzyme systems involved in the different biochemical reactions in the body.

These include blood glucose control, protein synthesis, nerve, and muscle function.

Second, there’s the Potassium, which is the electrolyte that supports proper nerve function and muscle contraction.

Additionally, this electrolyte plays a significant role in the body’s ability to regulate blood pressure. (3)

Lastly, we have Sodium, which is the electrolyte the body uses to control both the blood volume and pressure levels. (4)

Aside from these three essential electrolytes, your body may also get depleted of chloride, calcium, and phosphate. If you have electrolyte imbalance or disorder, here are some of the symptoms that you may feel:

  • Irregular heartbeat
  • Nausea
  • Vomiting
  • Lethargy
  • Abdominal cramping
  • Muscle cramping
  • Muscle weakness
  • Headaches
  • Irritation
  • Fatigue

Too Much Stress

Switching to a keto diet is a big leap, not just for you but more so for your body.

After all, it will be the one that will undergo lots of changes. This exposes your body to a lot of stress.

Stress is more than just a mental health issue as it can affect your body physiologically too. It may cause both mineral and hormonal imbalances. (5)

One of the most common symptoms of hormonal imbalance is fatigue.

Additionally, you will experience mood swings, headaches, puffy face, digestive issues, dry skin, increased thirst, increased hunger, sweating, anxiety, and many more.

Not Eating Enough Fat

The common mistake of first-time keto dieters is they focus on restricting carbs that they neglect the amount of fats their diet has.

Keep in mind that keto is more than just a low carb diet—it’s a high-fat diet too.

It’s important to emphasize this since your body will be relying on fats for energy sources.

If you’re not eating enough of it, you’ll undoubtedly experience low energy in your new diet.

Carbohydrate Intolerance

This is a lesser-known and more difficult-to-identify cause of fatigue on the keto diet.

Carbohydrate intolerance happens when your body is not able to metabolize certain types of carbohydrates properly.

When you consume more amounts of these carbohydrates than your body can tolerate, it will cause bloating, abdominal cramps, heartburn, and fatigue. (6)

How do I Overcome Keto Fatigue?

Considering all of the causes that we’ve enumerated, here are some of the various ways you can boost your energy levels in the keto diet:

Eat regularly.

It’s easy to forget about your meals when on the ketogenic diet since this type of low carb diet is satiating, so you won’t feel the hunger that often.

While this is good news for people aiming for weight loss, this can be bad for your energy levels.

When you don’t eat enough fats or food, your calorie intake will go down. When it drops too low, you won’t have the energy you need to accomplish things.

Because of this, you need to eat more frequently.

More important, avoid skipping meals.

Some people also choose to do intermittent fasting while on a ketogenic diet to achieve their weight loss goals faster.

This is not recommended, especially if you’re just starting on your keto journey.

You should wait for your body to be fully keto-adapted before you try this combination.

Track what you eat and check your macros.

For restrictive diets, like keto, you must make sure you’re hitting the right macro ratios. In keto, here are some macros guidelines you should keep in mind:

Your carbs consumption is low enough. (only 5 to 10% of your caloric intake)

Your fat intake is high enough. (65 to 80% of your caloric intake)

And you have enough protein intake in every meal. (20 to 35% of your caloric intake)

To do this, you need to note what you’re eating, not just per day but also per meal. You can do this by keeping a food diary.

Additionally, you should not just guess the macronutrient content of the foods you eat. You need to calculate your food intake as accurately as possible. You can do this by using food calculator apps.

Drink water.

This one’s pretty obvious.

If you pee a lot and feel tired, drink water, and satisfy the daily recommended water intake. The established guidelines is to consume 2.7 to 3.7 liters of water for women and men. (8)

Aside from replenishing the lost liquids from your body, consuming cold water can also help in the body fat burning process.

Watch out for your electrolyte levels.

To ensure that you’re getting enough electrolytes, you need to familiarize yourself with the recommended daily allowance.

These are the RDA for The different electrolytes that your body needs:

Magnesium: 320 to 420 mg per day

Potassium: 3500 to 4700 mg per day 

Sodium: 1500 mg per day (9)

Calcium: 1000 mg per day 

In addition to consuming foods that are rich in these electrolytes, you can also incorporate electrolyte supplements into your regimen.

Consume more fats.

How do I get energy on keto? When you’re on keto, your body gets energy from fats that you eat.

Keto diet is known for its fat loss ability. Not replenishing the fats your body burnt can decrease your energy level.

However, most people are afraid that overeating fats can be dangerous to their health.

For your information, there’s actually what we call healthy fats, and these are what we recommend that you adapt the fat as a source of energy for your body. Some of the best sources of healthy saturated fats in keto are the following food items:

Red meat (choose organic as much as possible)

High-fat dairy (butter, heavy cream, raw whole milk, and ghee)

Animal fats (tallow, lard, and eggs)

Plant-based fats (coconut oil and palm oil)

Take MCT Oils.

Another great source of healthy fats on keto is MCT or medium-chain triglycerides, mostly found in coconut oil.

The good news is these are available as supplements. These are some of the most recommended supplements for keto dieters. 

Add more salt to your diet.

More salt can help minimize some side effects that you may feel while your body is getting fat adapted.  

This is because consuming salt can help boost your sodium levels.

The good thing is it’s easy to incorporate salt into your diet. You can add more salt when cooking meals.

If you don’t like to eat salty foods, the next best thing you can do is add a teaspoon of salt to a glass of water or dissolve 1 bouillon cube in water.

The Bottom Line

Yes, you will feel tired when on the ketogenic diet.

The good news is the tiredness you’re feeling won’t last for long. It’s probably because of the changes that your body has to go through when switching to a new energy source.

But if you still feel tired even after most of your keto symptoms are already gone, you may need to carry out some tweaks to your current diet.

You can do this by taking supplements, changing your fat sources, or adjusting your macros and calorie consumption.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top