What Are the Symptoms Of Keto Flu, How Long Do They Last? Diet Named Worst for Healthy Eating

The high-fat, low-carb, ketogenic (keto) diet has been named the least healthy diet of 2022 by a panel of health and nutrition experts.

The panel, which includes nutritionists, specialists in diabetes and heart disease, and other diet experts, was gathered by U.S. News and World Report and asked to rank various diets according to their scores in seven categories.

The keto diet came last in the category of healthy eating and was one of the lowest-ranked diets overall.

Out of forty diets, only the Dukan diet, which puts the emphasis on stocking up on proteins, and the gut and psychology syndrome (GAPS) diet, which eliminates hard to digest foods, ranked lower than the keto diet overall.

The diet ranked highest overall was the Mediterranean diet, which encourages the consumption of fish, vegetables, fruits, and olive oil.

U.S. News and World Report said the keto diet is "a high-fat, low-carb diet designed to make your body enter a state where it's relying on fat for energy," with this state being referred to as ketosis.

The diet ranked highly in the organization's annual review of diets in just one category: short-term weight loss. One expert cautioned this doesn't mean embarking on such a diet would be a good idea, however.

The report stated that in terms of safety, one member of the expert panel said: "This plan could be dangerous for some." Others warned about the high-fat content and warned against anyone with severe diabetes, kidney disease, and heart disease from following the keto diet.

"This diet is fundamentally at odds with everything we know about long-term health," one expert told U.S. News and World Report.

What Is Keto Flu?

One well-known complication associated with the keto diet is the so-called "keto-flu."

Writing for the Havard health blog, clinical assistant professor at Tufts University School of Medicine and primary care doctor at Harvard Vanguard, Marcelo Campos MD, said: "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."

Campos added that the causes of keto flu are currently not well known. He wrote: "Well, we don't really know why some people feel so bad after this dietary change. Is it related to a detox factor? Is it due to a carb withdrawal? Is there an immunologic reaction? Or is this a result of a change in the gut microbiome?

"Whatever the reason is, it appears the symptoms attributed to the keto flu may happen, not to everyone but to some people, after 'cleaning up' their diet."

Intermountain Health says that symptoms of keto flu usually last for a week or less, but can, in extreme cases, last up to a month. It adds that these symptoms can be alleviated by easing into a dietary change.

Drinking lots of water can help replace minerals lost during the transition to a keto diet as can electrolyte supplements. Intermountain Health also advises light exercise and plenty of rest.

And scientific journals have recently started to take notice of keto flu. In 2020, PubMed published a study that looked at consumer mentions of keto flu from consumers.

Keto Diet
A stock image showing some of the foods that can be eaten on a keto diet. Experts have named the high-fat and low-carb diet the least healthy of 2022. samael334/Getty