Keto Flu – What is it and what can you do about it?

What is the keto flu?

Keto flu is a natural reaction that the body undergoes when it starts burning fat as a source of energy instead of burning carbohydrates (sugar).The flu occurs once you drastically stop introducing carbs into your diet.

Who is affected by keto flu?

All people who’ve started a low-carbohydrate diet are on the verge of developing keto flu. Following the withdrawal of carbs from the diet, the body becomes profoundly affected by the sudden changes and starts developing keto flu symptoms.

Keto Flu

Various hormones in the body also get affected as a result of low carb effect, altering their normal functioning. Once the hormones are affected, an electrolyte imbalance takes place in the body.

Different people experience different sets of symptoms once keto flu kicks in. Keto flu can’t be described as the real flu, this is because it’s not contagious. Despite the fact that it’s not contagious, the symptoms that you go through are quite similar to those of the real flu.

Once the symptoms develop and nothing is done, the condition can shift from mild to a full-blown flu condition. You’re recommended not to let the condition get to its full blow stage because it’s tiring.


What are symptoms? “These are signs or features that indicate certain changes in the body.” Well, now let’s take a look at the symptoms that ketoic patients develop. They include:

  • Headache
  • Nausea
  • Cramps
  • Lightheadedness
  • Diarrhea
  • Cough
  • Sniffles
  • Fatigue
  • Irritability
  • Sugar cravings
  • Brain/mental fog
  • Muscle soreness
  • Insomnia

These symptoms start to manifest within the first and second day that you withdraw carbs from your diet. For a regular person, this flu can last an average of one week. Sometimes the flu can last up to a month depending on the person’s body.

The severity of the flu will also depend on the person’s body. Once you have developed keto flu you won’t undergo all the listed symptoms above, you will only experience two, three or even experience none at all.

Why does keto flu affect distinct people differently?

This comparison is caused by something regarded to as metabolic flexibility. “This is the capacity for an organism to adapt fuel oxidation to fuel availability.” Metabolic flexibility is simply how a body can adapt to utilize a variety of fuel sources. Therefore your body can be classified as a metabolic gymnast or metabolic flexible.

There are a variety of factors that determine metabolic flexibility, but there are two main reasons that are well known;

1. Genetics

2. Lifestyle

Some people have insufficient enzymes rendering them less metabolic flexible. Once a person is less metabolic flexible it becomes quite difficult for the body to adjust and start adopting to ketone diet. Even more, there are those people who may be less metabolic flexible but their bodies adopt well due to certain genes that can switch to new fuel sources.

Lifestyle, on the other hand, is a key factor which contributes to this subject. If a body is fed on processed foods like refined sugar, then there is a possibility of it developing keto flu symptoms.

If you rarely use refined sugar and starches, then you may only experience mild keto flu symptoms or not encounter any signs at all.

People who are inactive and don’t take part in any exercise activity are less metabolically flexible compared to those people who exercise daily. So in case you are an inactive person, then you should take this advice into consideration and start leading a healthy lifestyle.

It’s difficult to understand and predict how most of the factors that act as a stimulant to metabolic flexibility will behave or react to a person’s body if carbs are restricted from the diet.

Why do people develop keto flu?

Understanding how keto flu develops is fundamental, this way you will be in a state to know how you can alleviate all the negative symptoms that arise.

What changes cause keto flu symptoms to occur?

Whether you are metabolically flexible or not, three certain changes occur in the body and these changes include;

1.    Increase in cortisol levels.

What is cortisol?

This “is a steroid hormone that regulates a wide range of processes throughout the human body, including metabolism and the immune response.”

Lack of carbohydrates in the diet creates a starvation alarm in the body. As a result of these low energy levels in the body, the body tends to release stress hormone cortisol. This in turn creates a lot of tension in the body.

Men that feed on diets rich in carbohydrates have a higher level of testosterone and low levels of cortisol compared to those that feed on a ketogenic diet.

This states that carbohydrates play a vital role in the body when it comes to testosterone and cortisol levels.

All those people who’ve made exercise a part of their life are not exceptional either. Low levels of carbohydrates in their diet will also contribute to an increase in cortisol levels.

If you fully convert to a ketogenic diet, then your body will appreciate the changes with time, and the cortisol levels will relatively decrease. This is because your body will switch to other energy sources like fat.

The length of keto-adaption is not specific, it all depends on a person’s body. Though you will have to be patient with keto-adaptation which can take up to seven days.

2.    Flushing out of sodium and potassium from the body.

Carbohydrates are essential in diets since they contain essential macronutrients, responsible for secretion of insulin.

What is insulin? Insulin “is a hormone made by the pancreas that allows your body to use sugar (glucose) from carbohydrates in the food that you eat for energy or to store glucose for future use.”

When insulin is utilizing excess energy (sugar) it also conveys impulses to the kidneys to retain water and sodium. Once insulin levels have dropped it releases sodium which takes with it plenty of water from the body.

This causes a 10-pound weight water loss during the early days of a ketogenic diet. Glycogen, (“a substance deposited in bodily tissues as a store of carbohydrates, a polysaccharide that forms glucose on hydrolysis”) together with fluid levels are directly involved as well.

The first five days that you introduce a ketogenic diet, the body responds by utilizing stored glycogen in the liver and muscle as a source of energy. Due to this effect, a pound of water is lost.

 Utilization of glycogen together with decreased insulin levels results to enough sodium and water which end up causing a variety of keto flu symptoms like;

  • Nausea
  • Headaches
  • Cramping
  • Gastrointestinal problems and
  • Dizziness

Once you start experiencing the above symptoms, you can avoid them by taking plenty of water and then supplement with minerals. Later, even after supplementing with minerals and fluids, you will still experience various keto flu symptoms such as brain fog and fatigue. It's also a good idea to use supplements that specifically help with the keto flu. These symptoms arise because of various hormonal changes.

3.    A decrease in T3 Thyroid hormone levels.

What’s Thyroid hormone?  “It’s a Chemical substance made by the thyroid gland, which is located in the front of the neck. This gland uses iodine to make thyroid hormones, which are essential for the function of every cell in the body”.

Carbohydrates and Thyroid hormone work hand in hand. Various studies that have been conducted concludes that T3 production in men is well regulated by carbohydrates.

In one study, it found that if there is a total restriction of carbohydrate in a diet, a 47% T3 decrease occurs significantly. This is very crucial because T3 is amongst the most effective thyroid hormones secreted by the human body.

T3 is more biologically potent compared to T4, even though it’s the most produced thyroid hormone in terms quantity.

With all the information on T3, we now understand that carbohydrate restriction can alter various changes to the thyroid gland and thyroid hormone. Though, the numerous studies carried out advocate that the differences vary from one person to another.

Always pay attention and get to understand how you feel when consuming different levels of carbs. If you experience specific symptoms of depression and fatigue, then you may be experiencing low levels of T3 and great reverse T3.

To that effect, it shows that if you restrict carbohydrates in your diet, it will make an impact on your thyroid function leading to release of more stress hormones.

Remedies to take against Keto flu.

A. Frequently supplement your diet with essential macronutrients.

The required minerals that you should supplement your diet with include;

1. Potassium

2. Magnesium

3. Sodium.

You should supplement the above minerals because they are rapidly lost due to insulin decrease while on a ketogenic diet which in turn causes the following symptoms;

  • Constipation
  • Headaches
  • Cramping
  • Fatigue and
  • Lightheadedness

What foods should you take that are rich in potassium?

When keto adapting, try to eat foods like;

  • Green leafy spinach
  • Avocados etc.

When it comes to sodium, you can use unrefined salt in your drinking water and also in your meals. During the first week when you introduce a ketogenic diet it’s recommended you use at least 5 to 7 grams of salt a day, that’s equivalent to one tablespoon.

Magnesium is another essential mineral in the list that will make your ketogenic diet bearable. Magnesium is not lost from the body like sodium is, especially once carbs are restricted in a diet. Magnesium is crucial because it;

  • relieves pain
  • Increase Insulin sensitivity and
  • Also, improve the quality of sleep

Foods rich in magnesium include;

  • Spinach
  • Almonds and
  • Pumpkin seeds

If you don’t prefer the above-listed foods, then you can opt to purchase supplements that will provide all your potassium and magnesium needs. A supplement by the name “potassium Gluconate” is suitable for all potassium needs and it’s sold in lots of stores.

On the other hand magnesium citrate is an excellent supplement for all your magnesium needs. It’s well recommended because of its;

  • Well absorbed and,
  • mild laxative to people whose bodies are sensitive

Dosages for the recommended Minerals


Men-400 mg a day.

Women-310 mg a day.


5-7 g of unrefined salt a day.


3,500 mg a day for people aged 16 years and above.

B. Drink a lot of water.

When on a ketogenic diet it’s important to keep your body well hydrated. Failure to do that and the body will be highly dehydrated which may lead to the development of adverse symptoms. Your body’s physical performance is impaired with as little as 2% water loss and a 2.8% of the total bodyweight to corrupt its full functioning.

That amount of water can only be lost within the first five days that you introduce a ketogenic diet to your body. This may end up resulting in negative keto flu symptoms.

Don’t wait till you develop the symptoms, take plenty of water sprinkled with unrefined salt.

How much water should you drink a day?


  • 19+ should drink 3.7 liters
  • 14-18 years old should drink 3.3 liters a day.
  • 9-13 years should drink 2.4 liters a day.
  • 4-8 years old should drink 1.7 liters a day.
  • Females
  • 19+ SHOULD drink 2.7 liters daily.
  • 14-18 years should drink 2.3 liters daily
  • 9-13 years should drink 2.1 liters daily.
  • 4-8 years should drink 1.7 liters daily.

Check the amount of water you ought to take per day in line with your age and gender accordingly. There is no problem though if you opt to drink more than stated in the list above. It is recommended to maximize your water intake during the first five days once you introduce your body to a ketogenic diet.

Drinking lots of water is essential to replace the amount of water lost during work out sessions.

If the above-recommended information is strictly followed then everything will be fine. Just don’t forget to sprinkle some unrefined salt in your drinking water.

C. Consume more fat.

To assist your body get going, you will have to nourish it with more fat. The liver cells are supplied with Acetyl-CoA that is derived from fat used to make ketones. How can you add fat to your diet? You can simply add fat bombs to your diet to supplement fat which should act as a source energy.

There is the only problem with feeding on fat bombs during the first days of carbohydrate restriction. Most of the fats are not readily utilized as fuel during the early days.

On the other hand dairy and animal fat take a long time to reach the liver. They have to go through the lymphatic system through the heart, to the muscle cells, fat cells then to the liver. Once the fats reach the liver, they are systematically converted to ketones. You don’t need to worry because of the delay, stored protein in the body will be supplementing your energy needs at that moment.

You can also adapt to supplement with MCT oil that helps your body a great deal. It helps you;

  • adapt to your new ketogenic diet very fast and also
  • Assist you to get rid of keto flu for good. It enables you to make it work efficiently especially when combined with exercises.

D. Prioritize your sleep.

Sleeping correctly will help you reduce stress levels. If you choose to be a ketogenic dieter, then sleep will be a priority among your other priorities. Lack of sleep will cause the following, it;

  • Will make adaptation to a ketogenic diet more difficult.
  • Will also increase cortisol levels.

You should at least sleep for a minimum of 7-9 hrs. If you feel tired in between the day you can take a 30 min nap.

E. Meditate to relieve stress.

Starting a ketogenic diet can be stressful. The reason behind this is because the level of cortisol is a bit high.

To reduce the high levels of cortisol, you’ll have to meditate frequently in between breaks of 15 minutes. Ways on how you can meditate are by taking slow, long and deep breaths. This will help your mind stay less reactive, making life as less stressful as possible.

What should you not do when having keto flu?

1.    Don’t consume too much protein

Over consuming proteins will increase insulin levels due to protein digestion. With insulin levels rising this means that the body will start using sugar as a source of energy instead of utilizing ketones and fat.

2. Don’t over exercise.

Over exercising will be stressful to a body which is battling a restriction from carbohydrates for the first five days. Without enough carbs to fuel such exercises the body will be torn apart by stress.

3. Maintain your stress levels.

High-Stress levels will weaken your body. Stress will increase T3 and cortisol levels making your life stressful.


Keto flu should not be treated as a virus. It’s just a carbohydrate restriction. This condition is manageable. If you are metabolically flexible, then you will not experience any keto flu symptoms at all. The less metabolically-flexible will undoubtedly experience keto flu symptoms.