A resurgence of an old health craze has hit the nation, and it may be doing more harm than good.

The ketogenic (keto) diet, otherwise known as the low carb high fat (LCHF) diet, is a nutrition plan focused on limiting carb intake to 20-40g per day to push the body into ketosis. The average body uses glucose from the food we eat, mostly carbohydrates, to create energy. Insulin is produced by the pancreas to regulate the sugar levels in the bloodstream and keep the body running at a stable energy level. When carbohydrates are restricted, the body begins to starve from the lack of sugar in the bloodstream, so it reverts to ketosis, a state in which ketones are produced by breaking down fat in the liver.

Ketosis is a natural process. It’s our body’s back-up generator, used for when food supplies are low so that we can keep running in times of danger. The idea behind the keto diet is to use up the fats normally stored for these times of danger as the main source of fuel, thereby eliminating fat in the body and ultimately leading to weight loss.

But does this really work when put into practice? And how long can the body run on its back-up generator before it suffers the consequences?

The human body needs carbohydrates. It is designed to take the glucose from these foods to produce energy and heat in the body. When this is taken away, the body reacts negatively. According to ruled.me (a website dedicated to promoting the keto diet), some of the most common side effects of the keto diet include heart palpitations, cramps, constipation, and reduced physical performance, while less common side effects include hair loss, gallstones, increased cholesterol, and a skin condition known as the keto rash. Many people also experience what’s known as the “keto flu,” which includes fatigue, headache, and nausea caused by the process of eliminating glucose stores in the body, extreme losses of electrolytes, and a lack of proper nutrients.

There is some basis to the benefits of the keto diet. Despite its new popularity, Dr. Ananya Mandal, M.D., said the diet was created in the 1920s to treat epilepsy in children who didn’t respond well to medication. It has been shown to decrease seizures in children with this condition and, according to Dr. Marcelo Campos, M.D., has been considered to treat other forms of brain disorders, but no further research has been conducted to support this theory.

In the 1970s, Dr. Atkins used the keto diet to create the fad diet known as Atkins, which begins with a ketogenic phase for two weeks. However, the theory of using the keto diet to promote weight loss, especially long-term weight loss, has not been supported by any scientific studies. In fact, Dr. Campos notes that diets that promote rapid weight loss, such as the keto diet, are actually linked to increased mortality. And if ketone production becomes too high, it can lead to a condition called ketoacidosis, which, according to ruled.me, is lethal and “responsible for over 100,000 hospital admissions per year in the U.S. with a morality rate of around 5%. In other words, ketoacidosis is to blame for about 5,000 deaths per year.” It is caused by a “combination of hyperglycemia, metabolic acidosis, and increased ketone body levels in the blood,” and is most common in people who have diabetes.

Additionally, the high-fat concept promoted by the diet with little regard to how it’s incorporated, has led many people to consume diets rich in red meat, high-processed and high-sodium foods, which are all linked to cancer and cardiovascular disease.

So, while there may be some research that supports eating less carbohydrates can lead to weight loss, restricting carbohydrates to the point of ketosis can be dangerous. Most importantly, carbohydrates do not need to be limited to that amount to promote healthy weight loss. Eating a diet with balanced levels of carbohydrates, proteins, and fats; limiting intake of processed foods; staying hydrated; and incorporating a regular physical exercise regimen can lead to all the benefits of the ketogenic diet without any of the nasty side effects. Besides, it will be much easier to enjoy life and go out without such heavy restrictions imposed upon the diet, and an improved, fulfilling lifestyle is what healthy eating is all about.