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Home » OSL Blog » What is Keto Flu & How to Avoid it: Ketogenic Fatigue Explained

What is Keto Flu & How to Avoid it: Ketogenic Fatigue Explained

July 5, 2019

Have you heard of the keto diet? Is it a diet that you’ve tried yourself? This diet has been around for almost 100 years and has resurged in popularity over the last few years.

We’ve already covered the specifics of the keto diet, so we won’t rehash it here. Today, we are going to talk about keto fatigue and how it affects your workouts. Later, we’ll provide a new solution that will not only help with the fatigue but also amp up your workout.

Anyone who has done this diet for any length of time can attest to the dreaded keto fatigue. Also called the keto flu, the symptoms that go along with changing your diet are not fun. A lot of people abandon the diet before they ever see results due to ketogenic fatigue.

But, what is keto fatigue and why does it happen?

What is Keto Fatigue?

The keto diet is based on a low carb diet. Most people eat much higher carbs per day before they switch.

Once you switch to the keto diet, you feel great for the first few days. By day three or so, you start to feel downright awful. This is when the keto flu starts to take hold.

Tired male
Burning fat fro energy on keto results in flu like symptoms.

But why do you feel so tired on the ketogenic diet? 

When you start really feeling tired and having other symptoms, that’s your body telling you the diet is working. Your body is transitioning from burning sugar for energy to burning fat.

At this point, your body is converting fat into ketones to use in place of glucose. Once the glucose is depleted, your insulin levels drop. At this point, your body also starts letting go of an important electrolyte, sodium.

The state of ketosis is when your body is using fat and ketones to create energy. This is when most people start seeing the effects in the form of weight loss.

Here are some symptoms that you will likely feel when you are entering ketogenic fatigue:

  • Sugar cravings
  • Muscle cramps
  • Brain fog
  • Unable to get motivated
  • More irritable than normal
  • Fatigue
  • Headache
  • Dizziness
  • Nausea
  • Diarrhea
  • Constipation
  • Insomnia 
Muscle cramps
Muscle cramps are one of the many symptoms of the keto flu.

Sounds a lot like the regular flu, right?

You might be feeling some of these symptoms along with some signs of ketosis. While the symptoms are no fun, luckily it tends not to last long. Most of these symptoms will resolve on their own after a week or two on the diet. 

Let’s take a look at some of the signs and symptoms to expect from ketosis.

Signs and Symptoms of Ketosis

1. Bad Breath

This is usually the first sign that people realize when they’ve entered ketosis. Why does it change the smell of your breath?

When you enter ketosis, your body has higher ketone levels. One of those ketones is acetone, which is eliminated through urination as well as breathing.

Bad breath
Having bad breath is one of the earliest symptoms of ketosis.

Some people have foul smelling breath while others have a more fruity smell. The most common solution is to chew sugar-free gum or brush their teeth more often. Some even carry a bottle of mouthwash or travel toothbrush and toothpaste with them to always stay fresh.

If you choose to go the gum route, make sure that you check for carbs. If you go over your carb allotment, then you’ll throw yourself out of ketosis and likely reduce the next symptom.

2. Weight Loss

This symptom is the reason that many people go onto a low carb diet like the ketogenic diet. For most, if not all, this symptom is always a positive one.

Many are surprised that they seem to lose a bunch of weight initially and then they plateau shortly after. This is because their body is shedding excess carbs and water weight once entering ketosis.

weight loss
Weight loss is an aftermath of ketosis and surely a positive one.

Once you’ve hit the plateau, you’ll have to continue with a caloric deficit to maintain weight loss. People who fought through the ketogenic fatigue often quit their diet now, out of frustration when the scale doesn’t change.

This diet is also popular with diabetics and their doctors to promote weight loss. When an equal amount of type 2 diabetics and non-diabetics were studied, researchers found positive results.

At the end of the trial, both sets of people showed weight loss compared to the control group. The control ate the equivalent of a healthy diabetic diet recommended by Diabetes UK.

This study follows two individuals who were able to not only lose weight, but also reduce or eliminate diabetic medications.This was after switching from a high-carb diet to a low-carb ketogenic diet.

Other Health Changes

Understanding the way this type of eating lifestyle changes your body is important. Without that knowledge, it’s easy to feel like it’s not working and give up.

While weight loss is a great benefit to the ketogenic diet, there are other health changes to be considered. Most are positive while others are more cautionary if you choose to do keto long-term.

There have been quite a few studies that have shown that eating a ketogenic diet can help with other concerns. Thirteen studies were reviewed when controlled for a very-low-carb keto diet. The results found that weight loss was the number one greatest outcome, as well as:

  • Reduction in high blood pressure
  • Increase in HDL cholesterol (good cholesterol)
  • Decrease in LDL cholesterol (bad cholesterol)
good cholesterol

Of five trials reviewed comparing an low-carb diet to a low-fat diet, the low-carb showed favorable changes in:

  • Triglyceride levels
  • High-density lipoprotein cholesterol values

This review showed little to no difference once the one year mark hit. It also cautions a negative change in low-density lipoprotein cholesterol values over the long-term.

Ketones in the Blood

Not everyone can determine if they are in ketosis from signs and symptoms alone. For those who can’t, there are other ways to confirm ketosis.

The best way to do it is by checking your blood. A small prick and drop of blood is all it takes to test, much like a diabetic checks their blood sugar levels.

Diabetes test
A blood keto meter is an easy way to check for ketosis.

To check, you’ll have to purchase test strips and a meter. The meter will test the levels of beta-hydroxybutyrate (BHB) in your blood. Most experts and nutritionists agree that a range of 0.5–3.0 mmol/L means you are in nutritional ketosis.

Let’s take a look at some of the things you might notice that confirm you are in fact in ketosis.

1. Uptick in Focus and Energy

Once you’ve been in ketosis and maintained for at least a few weeks, you might notice some exciting things. Most are thrilled when they start exhibiting greater focus and increased energy as a side effect. It is a welcome change from the brain fog and struggle to focus that the ketogenic fatigue causes early on.

Increased energy
Ketosis leads to an uptick in energy.

The reason you experience this as a long-term keto dieter is due to the ketones in your body. As they increase and continue to burn fat rather than glucose, your brain gets a flood of ketones.

increased focus
The increased ketone flow to the brain exhibits greater focus.

When comparing the low-carb diet to the American Dietetic Association (ADA) diet, researchers found participants with increased cognition. Once tested after the trial, they showed improved attention and reported less confusion on the low-carb diet.

2. Food and Alcohol Cravings

Many people struggle with various levels of food and alcohol addiction. One of the positive side effects of the ketogenic diet is that it curbs cravings for both in some people.

It is suspected that the elevated ketones change the way the brain reacts to hunger. Also, the increase in protein and vegetables that go along with the low-carb diet may alter hormones related to appetite.

Over an eight week period, 39 overweight or obese people were studies for appetite effects on the keto diet. While in ketosis, participants showed increases in the hormone ghrelin and reduction in amylin and leptin. They also reported a reduction in appetite and hunger.

Healthy shopping
With reduction in junk food & alcohol cravings, your grocery list is more wholesome.

In another study, 119 overweight participants were subjected to either a low-carb keto diet or low-fat diet. At the end, the ones who were on the keto diet reported less negative effects and a reduction in hunger.

This review of ketogenic diets compared to very-low-energy diets confirms a feeling of fullness and reduced hunger for keto eaters. It calls for a need to determine the minimum level of ketosis needed to reduce cravings.

With keto, hunger is reduced & fullness is reached faster.

Lastly, this study on twelve obese women who followed a keto diet for four months showed numerous improvements, including:

  • Reduction in appetite/hunger
  • Reduction in alcohol cravings
  • Increase in physical activity
  • Better sleep
  • Increase in sexual function
  • Overall increase in quality of life

3. Reduction in Exercise Performance

Now, while this is actually a negative for bodybuilders and gym goers, it’s only a short lived symptom.

When the body starts to change on the keto diet heading towards ketosis, glycogen stores are depleted. As we learned in this article, glycogen is the main source of energy created in the body. 

Until the body reaches ketosis and starts burning fat, you might find a reduction in performance when hitting the gym. However, you might be surprised by the results you have once you hit ketosis.

Reduction in performance is normal during the early stages of keto especially for high intensity sports.

A study followed 20 elite ultra marathon runners and ironman triathletes over an average of 20 months. Some were on a traditional high-carbohydrate diet while the others were on a low-carbohydrate diet. 

Those that were on the low-carb keto diet showed an increase of over 200 percent in fat oxidation after exercise. The key is that the body has to adapt to using fat for energy over carbs in order to be more proficient at running a long distance race. 

We talked about glycogen depletion earlier and how it affects your workout. To increase glycogen replenishment post workout, this study suggests a small amount of protein with small amounts of carbs. Suggested amounts are 0.2 – 0.4 grams of protein and 0.8 grams of carbohydrates to support muscle reconditioning.

4. Insomnia

Waking up at night or experiencing insomnia is a common symptom for people starting out on the keto diet. Most people are drastically cutting their carb intake when starting keto, which shocks the body. 

Some notice this change soon after starting the diet, while others find it happens later as their energy increases.

For most, the insomnia will resolve on its own after a few weeks, and you’ll return to your normal sleep schedule.

Insomnia is normal during the first few weeks.

This study backs up the claim of increased sleep quality while in ketosis. A large group of 262 Type 2 diabetics and 116 prediabetics confirmed not only improved sleep, but also improved health.

5. Digestive Upset

Many people cite either diarrhea or constipation in the early stages of the keto diet. This is to be expected, as you change the types of food you eat and the amount of protein, fat, and carbs.

Digestive upset
Digestive issues can rise due to the body transitioning into ketosis.

If you are struggling with one of these issues, hopefully we can provide some help. Here is a keto food list that you can use if you are suffering some digestive issues that should help:

  • Bell pepper
  • Asparagus
  • Mushrooms
  • Broccoli
  • Zucchini
  • Avocado
  • Green beans
  • Spinach 
  • Cauliflower
  • Lettuce
  • Cucumber
  • Garlic
  • Kale
  • Brussels sprouts
  • Onions
  • Celery
  • Tomato
  • Radish
  • Plain greek yogurt
  • Cottage cheese
  • Eggs
Mushrooms are keto friendly due to their relatively low carb content.

Make sure that you check the carbs when adding in these keto foods so you don’t fall out of ketosis.

Hopefully by adding a few of these keto friendly foods to your meals, it’ll help resolve the problems quickly. With the added benefit of eating healthier to help fuel your workouts and reduce keto fatigue.

The Effect on your Workout

Now that we’ve gone over all the signs and symptoms of keto fatigue and ketosis, let’s discuss your workout.

When you are just starting out or going through ketogenic fatigue, the last thing you probably want to do is workout.

However, now is not the time to walk away from your gym sessions. You’ve got goals, and you won’t meet them laying in bed and nursing your symptoms.

thinking in bed
Dedication and consistency are key to fight keto fatigue & power through workouts.

We get it. The keto fatigue is killing your workouts and hindering your gains. 

Well, good thing you’re here reading this now because we’ve got the perfect solution for you. This is something we’ve been working on really hard behind the scenes and we’re stoked to finally spill the beans.

The Solution to your Workout Fatigue

Worried that the ketogenic fatigue might hinder your workouts? Our new product, RK Pre-Workout, might be just the thing you need. A keto fatigue cure, if you will.

Created specifically with keto dieters in mind, RK Pre-Workout provides immediate as well as sustained release caffeine. What does that mean for your workouts? You won’t have that up and down feeling of energy followed by sluggishness during gym time. 

real keto pre workout
OSL’s real keto pre-workout will provide you with the energy you need to crush your workout.

Combined with creatine, phosphate, and vanadium, RK will be all you need to power through your workouts no matter what. The best part? No MCT’s or Exogenous ketones anywhere in the mix so you will not get any interference in processing your own ketones.

Go ahead, try it out! Once you do, let us know how much you love it.

Ready for some more tips to battle the ketogenic fatigue? Good, because we’ve brought them!

1. Increase your sodium intake

Remember earlier when we talked about losing an important electrolyte on the keto diet? Do you remember what it is?

We won’t hold you in suspense or even make you scroll back up. That important electrolyte is sodium.

Doubling up your salt intake will help with decreasing keto fatigue symptoms.

Without sodium you’re definitely going to feel the ketogenic fatigue hit you hard. A great way to combat the effects is to add a pinch or two of salt to your drink. We recommend pink himalayan salt, but you can use whatever type of salt you like. 

You can also increase your sodium intake by drinking and eating:

  • Bone broth
  • Chicken stock
  • Beef stock
  • Vegetable stock
  • Consomme
  • Chicken soup
  • Salted butter
bone broth
Consuming bone broth regularly is another way to increase your sodium intake.

2. Drink Up

On top of making sure your electrolytes are replenished, you’ll want to increase your water intake as well. Especially during the first week of starting the keto diet.

Electrolytes’ replenishment is highly dependent on increasing the water intake.

You should be drinking at least three liters of water per day in the first week. Even more if you are also putting in workouts, which you should be doing. Keep drinking that amount until you’ve pushed through the keto fatigue and are on the other side.

3. Slow Down on Carb Reduction

Most people eat more than 100 grams of carbohydrates per day on a normal diet. Once you start keto, you are going to be eating less than half that, and sometimes three quarters that amount.

One way to combat the effects of the keto flu is to taper down your carbohydrates over time. This way, it won’t shock your system as much as it does when you drastically cut the carbs out.

low carb salad
Slowly decrease your carb intake by having lower carb meals than before keto.

If you ease into the keto diet, rather than jump in feet first, you might reduce or eliminate the symptoms. This is definitely the case if you are doing a whole diet overhaul, rather than adjusting your macros. 

4. Increase Your Fat Intake

Typically, increasing your salt and water intake will resolve the ketogenic fatigue symptoms. If not, another tip to try is increasing your fat intake.

This is sometimes hard for people to do, especially if they are switching from a low-fat diet. 

Increase fat intake by adding high fat foods into your diet like ghee.

Basically, when you lower your carb intake without increasing your fats, your body goes into starvation mode. You’ve got to treat your body right at this delicate time, and increasing healthy fats might be the answer.

Need to some healthy fat ideas to add to your keto recipes? Try:

  • Olive oil
  • Tallow
  • Lard
  • Ghee
  • Salted butter
  • MCT Oil
  • Coconut oil
  • Fish oil

5. Wait to Lower Your Caloric Intake

Your body goes through a lot of changes when you start a low-carb diet. The last thing you want to do is change too many things at once.

If you want to reduce your calories so that you are in a deficit each day, hold off at the beginning. Let your body adjust to the new macros you’re providing before you do.

diet planning
Make sure to slowly decrease you calories during keto; good diet planning is key.

Once your body adapts to being in ketosis, you are likely going to start losing weight. Once the weight loss slows might be the right time to lower your daily calorie goal. 

6. Don’t Go Too Hard at the Gym

To help your body adjust, consider reducing the amount of time you spend at the gym. Also, do lighter activities while you’re starting out on the keto diet.

Tapering down your training intensity will make it easier for your body to adjust to keto.

You want to be kind to yourself while your body changes its fuel source. Once you reach ketosis, feel free to up your workouts again. And of course, you’ll have RK Pre-Workout there to help you out along the way.

We hope you enjoyed this article and the release of one of our new keto products.

Are you on living the keto lifestyle and suffered through the dreaded keto fatigue? What worked for you? Are you stoked to try our new products? Let us know in the comments!

Disclaimer: None of the individuals and/or companies mentioned necessarily endorse Old School Labs or COSIDLA Inc. products or the contents of this article. Any programs provided for illustration purposes only. Always consult with your personal trainer, nutritionist and physician before changing or starting any new exercise, nutrition, or supplementation program.
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Old School Labs™ is the maker of premium supplements that carry on the fitness values of the “Golden Era” of bodybuilding. Old School Labs™ products do not hide behind proprietary blends, contain no artificial sweeteners or artificial flavors, and are manufactured using only high-quality ingredients.

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