What Is Keto Flu And How Can You Beat It?

If you have been thinking about following a low carb plan like the keto diet, you have probably stumbled across the term keto flu before. Many keto dieters who have shared their experiences online often talk about some of the side effects they encountered during the first week of the diet. But what exactly is the keto flu? While the term ‘flu’ makes it sound like an incurable virus, it is actually not caused by a virus or ketosis at all. In fact, it is your body’s natural response to carbohydrate withdrawal and there is an easy way to beat the keto flu without falling off your diet.   

Understanding Carbohydrate Withdrawals

Over the years, our diets have comprised of chocolates, sugar-coated cereal grains, and let’s not forget the oh so heavenly baked goods. Indulging in these pleasures regularly seems harmless at the time but little do we realize that our bodies are becoming dependant on these carbs

Are carbohydrates really that addictive? Well, yes, for very simple reasons. Firstly, the body is able to break down carbohydrates and convert them into glucose much faster than any other source of fuel, the less work the better right? Secondly, during this digestive process, the region of the brain responsible for cravings and addictions also gets stimulated. 

Imagine indulging in your favorite cheesecake, after each bite, you feel a sense of pleasure and suddenly feel a rush of energy not long after. The reason we feel this way is because the sugar triggers the pleasure regions of the brain to release dopamine – the feel-good hormone. As for the sudden spike in energy, this is because the body can digest and convert the sugar into energy so quickly. But this pleasure doesn’t last very long. Once insulin and blood glucose levels have peaked, they begin to dip, what many call a sugar crash. This leaves us feeling sluggish and less energetic than we were before eating the cake, which automatically causes the brain to crave more. This response is very similar to that of a tobacco or substance addiction. 

Once carbs are limited it can be a shock to the system, which often results in withdrawal symptoms. Much like a smoker who is weaning off tobacco, the body goes through the same notions. The good news is that as your body becomes more fat adapt and the cells have gotten used to burning ketones for fuel instead of sugar, the symptoms start to subside. 

Keto Flu Symptoms

The keto flu can cause some flu-like symptoms, however, it varies from person to person. Some may experience these symptoms within a few days of restricting carbs while others may not experience any. The severity also varies from mild to severe depending on your health status and lifestyle. 

Common keto flu symptoms include:

what is keto flu?
  • Irritability
  • Fatigue
  • Weakness
  • Muscle cramps or spasms
  • Vomiting
  • Nausea
  • Constipation
  • Diarrhea
  • Stomach discomfort
  • Dizziness
  • Sugar cravings
  • Difficulty sleeping
  • Poor concentration

These symptoms can last for up to a week, but some individuals may experience them for longer. This is usually one of the reasons why many keto dieters give up on the diet early on. Fortunately, there are clever hacks that can help reduce the severity of these symptoms.

What Causes The Keto Flu?

To counteract these symptoms it is important to understand what causes the keto flu. It is not just your brain’s pleasure centers begging you for a delicious treat, it is changes that are happening on a deeper level. 

Carbohydrates signal the body to release insulin, a vital hormone that helps with the absorption of glucose from the bloodstream, which is then used by the cells as fuel. When there is a surplus in energy, insulin triggers the kidneys to retain water, potassium, and sodium (electrolytes). When following a carb-restricted diet, the opposite happens. When insulin levels start to drop, it signals the kidneys to excrete water, electrolytes, and other important minerals instead of retaining them. However, this is not the only water loss we experience while transitioning into ketosis. Since carbohydrates are no longer the main source of fuel, the body starts to use up its glycogen reserves. For every gram of stored glycogen, roughly 3 to 4 grams of water is stored along with it. During fat adaption, the body starts to break down the last of its glycogen stores and the excess water is also excreted from the body. The drastic loss of water and electrolytes is one of the main culprits behind keto flu symptoms. Headaches, muscle cramps, and dizziness are also a strong indication of dehydration. 

Some studies also suggest that there is a link between the keto flu and reduced T3 thyroid hormone levels. This suggests that restricting carbohydrate intake may have an effect on thyroid function and could be an underlying cause of symptoms such as fatigue, mood swings, and poor concentration. 

How To Avoid Keto Flu

Now that we know some of the underlying causes of the keto flu, these are a few easy ways to avoid it during the transition into ketosis.

Increase Your Water Intake

While your body is becoming keto-adapted, it excretes more water than the average glucose burner. During the first few days of the keto diet, you may notice that you have lost a few pounds. This is usually due to water weight and not fat. That is a significant amount of water to lose and without ample hydration, it can lead to many of the above symptoms. The best way to stave off keto flu symptoms is to drink more water. It is important to remember that the 8 glasses a day rule may not be enough to meet your body’s water requirements but rather a good rule of thumb is to drink water until your urine is a very pale yellow. 


Water is not the only thing that gets excreted during the transition. Vital electrolytes and minerals also get flushed down the drain. Taking a good quality keto supplement that contains essential ingredients like potassium, sodium, magnesium, and calcium as well as MCT oil and BioPerine® can help stave off these symptoms. Keto supplements don’t just rebalance electrolyte levels but also helps to reduce GI stress and maintain a healthy state of ketosis. 

Increase Your Fat Intake

You are slowly encouraging your body to use ketones, aka fat as it’s new fuel source. So to get your body fat adapt and give it the fuel it needs, you should be eating more fat. While meat and dairy are a great source of fat, it takes a while for the body to convert it to fuel. MCT oil is one of the best sources of saturated fat, which is not only healthy but also converted to ketones directly after it is digested. Make a few fat bombs to keep on hand or simply add MCT oil to your coffee for a quick boost of energy.

Other helpful ways to kick the keto flu:

  • Get more sleep.
  • Go for a walk or meditate to reduce stress.
  • Eat more vegetables that have a high water content such as cucumber, zucchini, and spinach.
  • Take it slow and adjust your macros if need be.
  • Avoid any high-intensity training while you are transitioning into ketosis.
  • Don’t overdo it with protein, it could induce gluconeogenesis and prevent you from entering ketosis.

Don’t Let The Keto Flu Discourage You

The keto diet can feel a bit overwhelming in the beginning stages. It will take your body some time to adapt to the new changes, but the important thing to remember is to start it at your own pace. Adjust your macros as you need to and take your time figuring out what works for your body. It is not a race. Keep your water bottle close, fuel up on MCT oil and most importantly, don’t forget to supplement. 

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