A long-term study reveals that while a ketogenic diet can limit weight gain, prolonged use may disrupt metabolism, potentially leading to impaired insulin secretion, fatty liver disease, and elevated blood lipids. This raises questions about the diet’s long-term safety as its popularity for weight loss and metabolic health continues to grow.
Ketogenic Diet’s Long-Term Effects: A Mouse Study Raises Concerns
Researchers found that extended adherence to a keto diet triggered metabolic abnormalities in mice, despite initial weight control benefits.
- A ketogenic diet led to less weight gain in mice compared to a high-fat Western diet, but more than a low-fat diet.
- Prolonged keto diet use resulted in glucose intolerance and impaired insulin secretion, even though the mice remained insulin sensitive.
- The study suggests that a very high-fat, very low-carbohydrate combination—rather than ketosis itself—may be responsible for the observed metabolic effects.
For those grappling with weight management, the ketogenic diet—high-fat, very low-carb—often feels like a quick fix. But a new study published in Science Advances suggests that long-term reliance on this eating pattern may come at a metabolic cost. Researchers discovered that while mice on a ketogenic diet gained less weight than those consuming a typical Western diet, prolonged adherence triggered a cascade of metabolic disruptions.
Weight Loss Isn’t the Whole Story
The research, conducted by scientists at University of Utah Health, involved adult male and female mice placed on one of four diets for nearly a year. These included a classic ketogenic diet (around 90% of calories from fat), a high-fat Western-style diet, a low-fat high-carbohydrate diet, and a protein-matched low-fat control. The team meticulously monitored body weight, fat composition, blood glucose, insulin dynamics, lipid profiles, and liver function, alongside cellular and genetic mechanisms linked to metabolic regulation.
While mice on the ketogenic diet did gain less weight than those on the Western diet, they still weighed more than those on the low-fat diet. In male mice, nearly all weight gain from the keto diet was fat mass, with no increase in lean mass. Female mice experienced increases in both, though their overall fat accumulation remained lower than those on the Western diet. Interestingly, switching mice from a high-fat diet to a ketogenic diet did result in weight loss, but a low-fat diet produced nearly double the reduction in body weight.
“Most of what we know about ketogenic diets comes from short-term studies or research focused narrowly on body weight,” said Molly Gallop, PhD, Assistant professor of anatomy and physiology, Earlham College and lead author of the study, who conducted the research as a postdoctoral fellow, University of Utah Health. “We wanted to understand what happens to broader metabolic health when this diet is followed long term.”
A Paradox of Metabolic Flexibility
Despite the weight control benefits, the ketogenic diet produced significant metabolic abnormalities. Over time, mice developed severe glucose intolerance that worsened with prolonged exposure. Unlike mice on the Western diet, which became insulin resistant, those on the keto diet remained insulin sensitive but were unable to regulate blood glucose because their pancreas failed to secrete adequate insulin when carbohydrates were introduced.
“The paradox is that these animals appear metabolically flexible in some respects but fail at a very basic level when challenged with glucose,” said Amandine Chaix, PhD, assistant professor of nutrition and integrative physiology, University of Utah Health and senior author of the study. “Blood sugar rises sharply and remains elevated, which is a dangerous pattern.”
What happens when your body can’t process sugar effectively? Researchers found that pancreatic beta cells in ketogenic-fed mice contained sufficient insulin and were structurally intact, but exhibited stress within the endoplasmic reticulum and Golgi apparatus—systems responsible for processing and transporting proteins. Microscopy revealed dilated and fragmented Golgi networks, effectively creating a cellular bottleneck that prevented insulin granules from being released into the bloodstream.
Lipid Overload and Liver Health
The study also identified pronounced hyperlipidemia. Ketogenic-fed mice showed significantly higher levels of triglycerides and free fatty acids than all other diet groups, including those on the high-fat Western diet. In male mice, this lipid overload contributed to hepatic steatosis, or fatty liver disease, along with elevated liver enzymes indicating impaired liver function. Female mice did not develop significant liver fat accumulation, a sex-specific difference researchers say warrants further investigation.
“One thing that becomes clear with extreme high-fat diets is that lipids have limited places to go,” Chaix said. “They tend to accumulate in the blood and the liver.”
Fortunately, many of these metabolic disruptions were reversible. When male mice were transitioned from a long-term ketogenic diet back to a low-fat diet, glucose tolerance normalized within weeks. Additional experiments showed that a high-fat, high-protein diet caused similar insulin secretion defects, suggesting that the combination of very high fat and very low carbohydrate intake, rather than ketosis itself, was responsible for the observed effects.
Implications for Obesity and Metabolic Disease
Although conducted in mice, the findings raise concerns about the growing rates of obesity and metabolic disease, particularly in regions like Mexico, where more than 70% of adults live with overweight or obesity and related conditions strain public health systems. Obesity has been formally recognized as a public health emergency, with associated diseases such as Type 2 diabetes, cardiovascular conditions, and hypertension contributing to premature deaths and healthcare costs.
Mexico has responded with measures like taxes on sugary beverages, mandated front-of-package warning labels, and restrictions on high-calorie foods in schools. These initiatives, while relatively recent, reflect a shift toward prevention and lifestyle-focused health strategies. However, changes in consumer behavior—like increased reliance on food delivery services during the COVID-19 pandemic—complicate these efforts.
This environment has spurred the development of nutrition-focused technologies, such as apps like MyRealFood and Yuka, which help consumers evaluate food quality. Personalized nutrition platforms, like nutriADN, are also emerging, applying genetic testing to inform dietary and lifestyle recommendations. According to Gustavo Rodríguez, CEO of nutriADN, the goal is to align nutritional decisions with individual metabolic predispositions, rather than promoting restrictive diets.
“There is a widespread perception that healthy living requires expensive products or extreme diets,” said Rodríguez. “But the fundamentals remain balanced nutrition, regular physical activity, adequate sleep and stress management.”
Clinical experts in Mexico caution against the uncritical adoption of diets like keto without medical supervision. Hospital-based obesity management primarily relies on hypocaloric diets, behavioral interventions, and physical activity, with pharmacological treatments and bariatric surgery reserved for specific cases. Limited training in nutrition can also lead to inconsistent dietary prescriptions.
The Utah study adds to the growing debate over the long-term metabolic consequences of extreme dietary patterns. While ketogenic diets may offer short-term benefits, the findings suggest sustained use could carry tradeoffs that aren’t immediately apparent when weight is the primary focus. The researchers stressed that their findings shouldn’t be interpreted as direct clinical guidance for humans, but rather as a signal that long-term metabolic effects deserve closer scrutiny. Gallop advised individuals considering ketogenic diets to consult healthcare providers and view diet as part of a broader, sustainable approach to metabolic health.
