keto diet 'a recipe for bad health,' study warns

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a review says the long-term risks of the high-fat, low-carb diet don’t come close to outweighing any weight loss or other health benefits

by dave yasvinski

published aug 04, 2021

last updated feb 20, 2025

2 minute read

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2 minute read

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researchers say there are long-term risks to the keto diet, based largely on fats and protein. getty

widely advertised as a safe way to shed pounds, going keto actually presents serious health risks to pregnant women, people with kidney disease and almost everyone else, according to a sweeping review of research into the trendy menu modifier.

the review, published in the journal frontiers in nutrition, found the long-term risks of the high-fat, low-carb diet — including cancer, heart disease, diabetes and alzheimer’s — don’t come close to outweighing any weight loss or other health benefits touted by eager advertisers.

“the typical keto diet is a disease-promoting disaster,” said lee crosby, lead review author and nutrition education program manager at physicians committee for responsible medicine. “loading up on red meat, processed meat and saturated fat and restricting carbohydrate-rich vegetables, fruits, legumes and whole grains is a recipe for bad health.”

ketogenic diets typically promote foods that are high in fat, moderate in protein and low in carbohydrates in an effort to induce a metabolic state known as ketosis, where the body burns fat for fuel instead of carbs. they have been touted as an effective way to lose weight and, less frequently, to help with seizure disorders, type 1 and type 2 diabetes, cancer, alzheimer’s disease and heart and kidney health.

the review found the diet to be risky for pregnant women because low carb diets are linked to an elevated risk of neural tube defects in babies — even in mothers taking folic acid as a precaution. the high protein diet was also found accelerate kidney failure in patients with kidney disease and raise levels of bad cholesterol in some patients. long-term, the proposition becomes dicier as the focus on low-carbohydrate foods typically steers dieters in the direction of cancer-causing foods and those linked to many of the other conditions it claims to help or eliminate: heart disease, cancer, diabetes and alzheimer’s.

the only intended use of the keto diet that researchers found to be supported by science was for the reduction of seizures in some people with a drug-resistant form of epilepsy — but even in this instance, it was found to cause fatigue, headache, nausea, constipation, hypoglycemia and acidosis in some people, particularly in the early days of the regimen.

an online survey of 300 users analyzed by researchers found self-administered diets may produce a series of symptoms commonly referred to as “keto flu,” adding dizziness, brain fog, gastrointestinal discomfort, decreased energy, feeling faint and heartbeat alterations to the list of concerns.

“ketogenic diets have low long-term tolerability and are not sustainable for many individuals,” researchers wrote. “diets low in carbohydrates have also been associated with an increased risk of all-cause mortality, although recent data suggest that lower-carbohydrate diets can be linked to either higher or lower mortality risk, depending on the quality of the carbohydrate they contain and whether they rely more on animal protein and saturated fat or plant protein and unsaturated fat, respectively.”

the team concluded that going keto, even for weight loss, was not worth the effort.

“in addition to the significant risks to kidney disease patients and pregnant women, keto diets are risky for others, too, as these diets can increase ldl cholesterol levels and may increase overall chronic disease risk,” crosby said. “while keto can reduce body weight short term, this approach is not more effective than other weight-loss diets.”

dave yasvinski is a writer with healthing.ca