What is Ketosis?

What is Ketosis?

Ketosis is a normal metabolic process characterized by increased ketone production. Ketosis happens when the body does not have enough glucose to make energy, so it burns fats instead. This results in a buildup of ketones in the blood.

Normally, your blood ketone levels are below 0.3 mmol/l. But after a prolonged fast or when you follow a ketogenic diet, blood ketone levels rise to 3-7 mmol/l. When this happens, you are in ketosis.

About Ketosis

Your body can make energy from three macronutrients: carbohydrates, proteins, and fats. While the body can use any macronutrient to make energy, it prefers using carbohydrates. This is because carbohydrates are economical, requiring fewer steps and less energy to fuel your cells. Another reason is that brain cells cannot use fats or proteins to make energy.

Before your body can utilize carbs, it needs to break them down into simple sugar molecules called glucose. Glucose then circulates your blood so that your brain is never short of its main fuel supply. But what if you stop eating carbohydrates?

Well, in the absence of carbs, the body releases fatty acids to make energy. Because the brain cannot use fats, the liver converts a portion of the released fatty acids into ketones, which now fuel the brain but also the muscles and heart.

If you want to learn how to achieve this metabolic state, read our guide on how to get into ketosis.

Facts and Myths About Ketosis


Ketosis is a normal metabolic process, but that's often portrayed in a negative light. Ketosis myths are mostly the result of it being confused with ketoacidosis. Researchers also disagree about the nature of ketosis, further feeding into these myths. Below, you will find common ketosis facts and myths explained.


Ketosis is normal

Evolution designed ketosis to help us survive in times of starvation and food scarcity. Your body is also always in a mild state of ketosis. For example, following an overnight fast or a vigorous exercise, your blood ketone levels increase [1].

Ketosis is healthy

Ketosis provides a range of unique health benefits like glycemic control, weight loss, and even cancer prevention. Ketosis also enhances autophagy, which is your body's recycling system linked to good health and longevity [2].

Ketosis takes time

Despite what you may have been told, it takes time to get into ketosis. Before your body can start making ketones, it needs to deplete its 600g of glycogen stores [3]. Learn how long it takes for the body to go into ketosis.

Ketosis induction is difficult

Before your body can make the switch to full-blown ketosis, it goes through a crisis period. This crisis is often called the "keto flu" and can last between 2 and 7 days. Symptoms of the keto flu include fatigue, pain, and nausea. Luckily, the keto flu tapers off as you get into ketosis.


Ketosis is dangerous

Ketosis is not dangerous. It is a normal physiological reaction to low blood glucose levels and is an adaptive response. The reason ketosis is considered dangerous is that it is confused with ketoacidosis. Ketoacidosis is when blood ketone levels rise above a normal threshold due to uncontrolled production. This only happens with untreated type 1 diabetes, severe alcoholism, or starvation.

Ketosis is bad for diabetics

People with type 2 diabetes can benefit from a ketogenic diet and being in ketosis. A growing number of studies is looking into ketosis as a treatment for diabetes mellitus [4]. For people with type 1 diabetes, ketosis can also help manage their condition. However, type 1 diabetics need to monitor their ketone levels carefully and adjust insulin medication to avoid ketoacidosis.

Ketosis makes you lose weight

This one is true to some extent. Your body spends a lot of energy supporting ketosis, which can create an energy deficit. But if you eat a lot of fat, then you may be creating an energy surplus that prevents your body from burning its own fat stores. For this reason, many keto dieters and experts will tell you that keto-adaptation plays a bigger role in weight loss than ketosis.

Ketosis starves the brain

This myth was created as a result of the assumption that your brain cannot survive without carbohydrates and glucose. This is simply not true. In fact, the brain can function normally and even better on ketones than on glucose according to current studies [5].



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