A new study from University of Utah Health raises concerns about the long-term safety of the ketogenic diet, a popular eating plan that’s often used for weight loss and managing type 2 diabetes.
While the keto diet is known for helping people lose weight and was originally developed to treat epilepsy, researchers now say it may lead to serious health problems over time.
The ketogenic diet is very high in fat and very low in carbohydrates. It puts the body into a state called ketosis, where it burns fat for energy instead of sugar.
This change helps control seizures in people with epilepsy and has made the diet popular for its fast weight loss effects. But until now, most studies have only looked at short-term results, not what happens when the diet is followed for months or years.
To learn more, researchers led by Dr. Molly Gallop studied mice over a long period. The mice were split into four groups, each eating a different diet: a high-fat Western diet, a low-fat high-carb diet, a protein-matched low-fat diet, and a classic ketogenic diet.
The mice were allowed to eat freely for nine months or more. During that time, the scientists tracked their weight, blood sugar, fat levels, and liver health.
As expected, the ketogenic diet helped prevent weight gain. Mice on the keto diet stayed slimmer than those on the high-fat Western diet. They gained less weight, and most of it was fat, not muscle.
However, there were hidden problems. Mice on the keto diet started showing signs of serious health issues, including fat building up in their livers—a condition known as fatty liver disease.
This disease is dangerous and often seen in people with obesity and metabolic disorders. While male mice developed clear signs of fatty liver and poor liver function, female mice did not, and the reasons for this difference are still unknown.
Even more concerning was what happened with blood sugar. At first, mice on the keto diet had low blood sugar and insulin, which might sound like a good thing. But when they were given even a small amount of carbohydrates, their blood sugar spiked to dangerously high levels and stayed high for a long time.
The researchers discovered that the mice’s pancreas cells weren’t producing enough insulin to bring blood sugar down. These cells seemed stressed by the constant fat in their environment and couldn’t function properly.
The good news is that some of these problems went away after the mice were taken off the ketogenic diet. This suggests that the damage to blood sugar control may be reversible if the diet is stopped early enough.
Although mice are not the same as humans, the study gives us important clues. It shows that the keto diet may come with risks that haven’t been fully understood—especially for people planning to stay on the diet long-term. The researchers advise anyone thinking about trying keto to speak with their doctor first.
This study offers a more complete look at how the keto diet affects not just weight, but liver function and blood sugar regulation. While the diet can help with weight control, it may also cause serious problems in other areas of metabolic health.
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The study is published in Science Advances.
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