diet, Nutrition

Keto Flu: Symptoms And Causes

Ketogenic diet was first used in the treatment of epilepsy patients in 1921 by Russel Wilder. He was the one who coined this term. However, ketogenic diet has gained popularity due to its effectiveness in losing weight and in improving overall health on a natural way.

The diet is very low in carbohydrates, high in fat and moderate in protein. While the diet is considered safe for most people, it’s associated with some unpleasant side effects.

The keto flu, also known as the carb flu, is a term coined by followers to describe the symptoms they experience when beginning the diet. In this article you will understand about keto flu symptoms and causes.

sick women in black lying on a couch drinking coffee

What Is Keto Flu

The so-called keto flu is a group of symptoms that may appear two to seven days after starting a ketogenic diet. Headache, foggy brain, fatigue, irritability, nausea, difficulty sleeping, and constipation are just some of the symptoms of this condition, which is not recognized by medicine. A search for this term yields not a single result on PubMed, the library of indexed medical research journals. On the other hand, an internet search will yield thousands of blogs and articles about keto flu.

It is tricky to describe exactly what happens after the diet change, because we are left with only our own observations and experiences. These symptoms may not even be unique to the ketogenic diet; some of my patients describe similar symptoms after they cut back on processed foods, or decide to follow an elimination or an anti-inflammatory diet.

The Symptoms of The Keto Flu

For the average person, the keto flu lasts about one week, and symptoms usually begin in couple of days of carbohydrate restriction. In some individuals, the keto flu symptoms can last up to a month.

Common symptoms of keto flu are:

  • Sugar cravings
  • Irritability
  • Insomnia
  • Lack of concentration
  • Brain fogging
  • Nausea
  • Stomach ache
  • Cramping or muscle soreness
  • Dizziness

Majority of the keto beginners experience one or two of these symptoms or none at all. The symptoms you get, the severity of your symptoms, and the length of the keto flu will vary from person to person.

Causes of Keto Flu and Its Symptoms?

Once we know the “why” behind the symptoms keto flu, we can understand how to alleviate these symptoms. Once you restrict carbohydrates, these three changes that happens in your metabolism are the main cause of commonly encountered keto flu symptoms:

1. Increase In The Levels Of Cortisol Hormone

During the initial few days ketogenic diet triggers a starvation-like response in the body. In response to this there is a surge in the levels of stress hormone like Cortisol.

What’s the association between ketogenic diets and cortisol?

One recent study compared the effects that low-carbohydrate diets and high-carbohydrate diets had on the cortisol and testosterone concentrations of normal men. The men on the high-carbohydrate diet had significantly higher testosterone levels and lower cortisol levels than the men who were on the low-carbohydrate diet.

Exercise training seems to increase this gap even more. In another study, researchers wanted to see the changes that 60 minutes of moderate intensity exercise training would have on free testosterone:cortisol ratio. They split the people into two groups: a 60% carbohydrate diet group and a 30% carbohydrate diet group. The lower carbohydrate group had a 43% decrease in free testosterone:cortisol ratio, while no statistically significant change occurred in the higher carbohydrate group.

These studies suggest that — whether you are exercising or not — a lower carbohydrate diet may increase your cortisol levels. You will know if you have higher cortisol levels than before if you feel generally irritable and your sleep quality decreases.

Once you are more keto-adapted, however, your cortisol levels are likely to decrease because you will be using more ketones and fat for fuel instead of sugar. Unfortunately, this process can take a few weeks, depending on your metabolic flexibility, lifestyle, and diet.

However, it is possible to bust through the keto flu and expedite keto-adaptation, even if you are metabolically more rigid than a tree. All you have to do is implement the strategies found in the next section.

2. Decrease In T3 Hormone Levels

There are several studies that shows the close relation between thyroid function and carbs intake. One study concluded that “dietary carbohydrates are an important regulatory factor in T3 synthesis in men.”

This study showed that a complete carbohydrate restriction lead to a 47% decline in T3. This is important to know because T3 is the most potent thyroid hormone that our body makes. It is 5 times more biologically active than T4 (the thyroid hormone that is typically produced in greater quantities).

So, if we have T4, then T3 doesn’t really matter, right? Let’s take a closer look at the research to find out.

In another study, high Free T4, high reverse T3 levels (the inactive form of T4), and low T3 levels were associated with lower physical function in elderly men. The opposite was associated with decreased mortality risk.

With these results, it seems that a drop in T3 levels that is accompanied by an increase in reverse T3 levels is something to avoid. Unfortunately, this may be exactly what happens when we restrict carbohydrates.

Another study done with 8 groups of obese individuals, researchers found that different amounts of dietary carbohydrates affect T3 and reverse T3 levels in different ways. T3 levels only decreased when the subjects consumed 120 grams of carbohydrates per day or less (regardless of how calorie-restricted they were). Reverse T3 levels, on the other hand, began to increase when carbohydrate intake was between 40 and 50 grams of carbohydrates per day.

This suggests that there are certain thresholds of dietary carbohydrate that can cause changes in thyroid and thyroid hormone function. However, the results from different studies indicate that this varies from person to person.

In the first study I mentioned, for example, they found no rise in reverse T3 unless the subjects were restricted to 800 calories a day.  On the other hand, the study done on the 8 groups of obese individuals found that their reverse T3 levels increased when they ate less than 50 grams of carbohydrates.

To figure out how to apply these findings to you, you must be mindful of how you feel while you are eating varying amounts of carbohydrates. If you are feeling fatigued, depressed, and are struggling to concentrate, then you may have lower T3 and higher reverse T3. This reflects that restricting carbohydrates to that level is impacting thyroid function and causing some keto flu symptoms.

Fortunately, this aspect can be taken care in many cases, After having an understanding of the third cause of keto flu.

3. Increased Loss Of Water And Sodium From Body

Restricting carbohydrates means creating a deficiency of one macronutrient that triggers most of the insulin release. As you know that insulin helps transport sugar into cells for fuel, but you might not know that how insulin can have an effect of the functionality of kidney’s.

While insulin is letting the cells know that there is excess energy, it also triggers the kidneys to hold onto sodium and water. As soon as insulin levels drop, sodium is released from the body, taking water along with it. This can cause up to 10 pounds of water weight to be lost during the first 5 days of the ketogenic diet.

Glycogen (the body’s storage form of sugar) and fluid levels are intimately connected as well. Every gram of glycogen is stored with around 3 grams of water. Thus, when we breakdown glycogen, some water will be released as well.

During the first day of the ketogenic diet, your main fuel source becomes the stored glycogen from your liver and muscle. This can lead to an extra pound to a pound and a half of water loss.

Together, glycogen loss and low insulin levels can cause us to excrete so much water and sodium that we experience some of the most common keto flu symptoms, such as dizziness, nausea, cramping, headaches, and gastrointestinal issues. Fortunately, these symptoms can be avoided by drinking plenty of water and supplementing with the right minerals.

However, the fact is that, even if you replenish your fluids and minerals, you may still experience keto flu symptoms. And this response varies from individual to individual.

Thanks For Reading!!!

Some Must Reads:

  1. 10 Symptoms And Signs Of Ketosis
  2. Ketogenic Diet: An Introduction
  3. Health Benefits Of Ketogenic Diet
  4. Ketogenic Diet Chart: What To Eat And What Not To Eat

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