Is Keto diet really good for humans? Study suggests weight loss benefits but raises cholesterol concerns

The ketogenic (keto) diet is a popular high-fat, low-carbohydrate eating plan often used to help control seizures and support weight loss. However, its long-term safety for managing conditions like diabetes or obesity is still uncertain. According to Medical News Study (MNT), a recent mouse study suggests the ketogenic diet may aid weight loss, but it could also lead to elevated cholesterol levels.

Mice on a high-fat, low-carb diet showed significant reductions in body weight and fat, indicating potential benefits for humans seeking to manage weight. However, researchers also observed increases in blood cholesterol, raising concerns about cardiovascular health.

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A study published in Science Advances, cited by Medical News Today, found that mice maintained on a keto diet for nearly a year developed high blood lipid (fat) levels, fatty liver disease, and reduced ability to regulate blood glucose. The impaired glucose control was linked to insufficient insulin secretion. In mice with obesity, the keto diet proved effective for weight loss but still showed harmful effects on overall metabolic health.

According to Amandine Chaix, PhD, an assistant professor of nutrition and integrative physiology at the University of Utah and one of the study authors, the effects of the keto diet on glucose regulation were reversible once the diet plan is stopped.

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"Results suggest that more studies are warranted in humans to establish the cardiometabolic benefits and risks of prolonged [keto diet] feeding," Chaix told MNT.

These particular findings highlight the importance of weighing the long-term risks of a keto diet in clinical use, despite its weight loss potential, and stress the need for further research in both animals and humans.

WHAT IS A KETO DIET?

The keto diet is a high-fat, low-carbohydrate dietary plan that has been used for more than a century to manage epilepsy and, since the 1970s, as a weight management strategy. Depending on the variation, fat can account for 70% to 90% of daily calorie intake, with the classic keto diet relying on 90% fat. I

Its primary mechanism is shifting the body’s energy source from carbohydrates to fat. Normally, carbohydrates are broken down into glucose and stored as glycogen in the liver and muscles for energy. When glycogen stores are depleted, either through fasting or through a keto diet, the body turns to fat metabolism.

Fats are broken down into ketone bodies, which act as an alternative fuel source for the body, including the brain. This metabolic switch, known as ketosis, is central to the diet’s therapeutic and weight loss effects.

CAN MICE STUDIES BE APPLIED TO HUMANS?

The bigger question is whether the results seen in mice can be directly applied to humans. Speaking to MNT, Chaix explained that the key aspect of the study was that the mice were maintained on a keto diet for nearly a year, providing insight into its long-term effects.

"Our diet intervention was maintained for about a year, which represents approximately one third of a mouse’s lifespan, allowing us to assess long-term consequences of feeding a keto diet versus much faster than we could in humans."

"[Furthermore], this is a very comprehensive study that carefully examined multiple biomarkers of cardiometabolic health, including a glucose challenge mimicking what may happen in people going off a keto diet," Chaix added.

The researchers also highlighted that the keto diet used in their study had a much higher fat content than what is typically followed by individuals. Specifically, it consisted of a ratio of 4g of fat to 1g of carbohydrates and protein combined.

"To address this, we also put mice on a high protein, high-fat non-ketogenic diet which caused similar problems to a ketogenic diet and thereby suggesting that other high-fat, low-carbohydrate diets, like what many people consume, may also pose a risk to metabolic health if our mouse models recapitulate what happens in humans," Molly Gallop, PhD, the first author of the study, told MNT.

Gallop further stressed that a key limitation of the study is that it was conducted in mice, meaning the outcomes may not fully reflect what would occur in humans.

"While there is evidence that hyperlipidemia is a side effect of a ketogenic diet for epilepsy treatment in children, and other studies in humans suggest that a ketogenic diet impairs the body’s ability to respond to glucose, our study warrants more research in humans," Gallop added.