Ketogenic diets, known for their very low carbohydrate intake, continue to gain popularity around the globe. However, according to a new analysis in Frontiers in Nutrition, the risks of such diets may outweigh the benefits.
“Very-low-carbohydrate (ketogenic) diets have been promoted for weight loss and, less commonly, for other health reasons,” wrote first author Lee Crosby, RD, LD, of the Physicians Committee for Responsible Medicine, and colleagues. “This review summarizes the effects of a ketogenic diet on health conditions for which it has been promoted, as well as potential long-term effects on health.”
Crosby et al. reviewed data from a wide variety of studies, meta-analyses and surveys, examining the impact a ketogenic diet may have on a person’s metabolism, diet quality, weight management and risk of developing adverse health conditions.
Keto diets are associated with significant weight loss, for example, and some researchers believe they “may decrease hunger.” These diets have also been found to reduce seizure frequency in some patients with drug-resistant epilepsy.
The authors did warn that following such a diet may cause a person to lack certain “vitamins, minerals, fiber and phytochemicals found in fruits, vegetables and whole grains.”
“Low-carbohydrate diets are often low in thiamin, folate, vitamin A, vitamin E, vitamin B6, calcium, magnesium, iron, and potassium,” they wrote. “In the absence of multivitamin supplements, individuals on low-carbohydrate diets are at risk of frank nutritional deficiencies.”
What about keto diets and cardiovascular issues?
“The effect of low-carbohydrate diets on plasma lipid concentrations is a major concern,” the authors wrote. “It has long been established that weight loss by any means causes a reduction in total cholesterol of about 2 mg/dL per kilogram lost. However, low-carbohydrate diets are often an exception to that rule.”
Crosby and colleagues also emphasized that the cardiovascular impact of a keto-like diet varies from one person to the next. In some studies, LDL cholesterol—often known as “the bad cholesterol”—has increased significantly in participants who follow keto-like diets for an extended period of time. On the other hand, one study found that there is no change in LDL cholesterol when patients with type 2 diabetes follow such a diet.
The latest on diabetes
Crosby et al. noted that keto diets “can improve glycemia in pediatric patients with type 1 diabetes.” However, they added, the risk of malnutrition, reduced bone density and difficulty sleeping are just some of the reasons why these diets are “generally not used in this population.”
In adults with type 1 diabetes, meanwhile, the authors found evidence of both positive and troublesome outcomes. One study, for example, found that keto diets can improve blood glucose control. The authors of another analysis, however, “strongly discourage sustained ketosis” for these patients.
When it comes to type 2 diabetes, studies have shown that a keto diet can “depress appetite, promote weight loss, reduce blood glucose values and decrease hemoglobin A1c in the short term.” Improvements in insulin sensitivity have also been noted, though some research suggests this is a temporary benefit as opposed to one that can be sustained for years at a time.
The foods commonly found in keto diets—meat, eggs, cheese and fish, to name a few—have all been tied to an increased risk of type 2 diabetes. When it comes to research specifically focused on these diets and type 2 diabetes, however, the results have been mixed.
One study, for instance, found that there is “no link” between such diets and the risk of type 2 diabetes among women. A separate study found that such diets may put men at a much higher risk of type 2 diabetes.
The bottom line …
The authors found that these diets have been associated with multiple benefits as well as multiple risks.
“Foods and dietary components that typically increase on ketogenic diets are linked to an increased risk of chronic kidney disease, cardiovascular disease, cancer, diabetes, and Alzheimer's disease, whereas intake of protective foods typically decreases,” they concluded. “Current evidence suggests that for most individuals, the risks of such diets outweigh the benefits.”
The full review, which includes more than 120 references, is available here.
Author’s note: In recent years, many other researchers have shown support for the keto diet as a way to improve cardiovascular outcomes. Previous Cardiovascular Business coverage examining the potential benefits of a keto diet can be read here, here and here.
Also, the Physicians Committee for Responsible Medicine funded this study; they have been known to promote plant-based diets.
Find more content on diet and relation with cardiology:
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Mediterranean diet benefits coronary heart disease patients
Plant-centered diet tied to lower risk of CVD in young adults, older women
Plant-based diets boost cardiovascular health, lower risk of severe COVID-19
Michael has more than 16 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.