A new scientific study has cast fresh doubt on the long-term safety of the ketogenic diet, a popular high-fat, low-carbohydrate eating plan that has been widely adopted for weight loss and metabolic control. Published on November 14, 2025, by researchers at the University of Utah Health, the study found that prolonged adherence to the keto diet may lead to hidden metabolic risks, including impaired insulin secretion, fatty liver disease, and increased markers of cardiovascular risk. The research, conducted on animal models, offers one of the most detailed examinations to date of how sustained ketogenic eating can impact organ function and metabolic regulation.
The researchers placed adult mice on one of four diet plans for a period lasting more than nine months. The ketogenic group consumed a diet rich in fat and extremely low in carbohydrates, mimicking the human version of keto that typically promotes weight loss by shifting the body into a state of ketosis. While the mice on the keto diet did not gain weight compared to those on a standard high-fat Western diet, they began to show troubling internal signs. Their insulin-producing pancreatic cells became dysfunctional, showing a significantly reduced ability to secrete insulin in response to glucose. This impairment led to higher blood sugar levels following a carbohydrate challenge, suggesting the development of glucose intolerance.
In addition to disrupted insulin regulation, the mice developed signs of liver damage. Male mice, in particular, accumulated significant fat in their liver tissues—a hallmark of non-alcoholic fatty liver disease. This liver dysfunction is particularly concerning, as it often progresses without overt symptoms but can eventually lead to more serious liver conditions. Female mice appeared to be partially protected from this effect, but still experienced some metabolic strain, indicating that sex-specific biological differences may play a role in the body’s response to prolonged ketogenic eating.
The study challenges the increasingly common perception that ketogenic diets are universally safe or beneficial when followed over extended periods. Although short-term studies have consistently shown benefits such as rapid weight loss, improved insulin sensitivity, and reduced appetite, this new research suggests that the same diet may trigger harmful changes when adopted for months or years. It highlights the complexity of nutrition science, especially when it comes to understanding how dietary patterns affect multiple physiological systems over time.
Experts responding to the findings have urged caution, especially among individuals who use the keto diet for general wellness or weight management without medical oversight. While ketogenic therapy remains a medically approved treatment for certain conditions, such as drug-resistant epilepsy, its use in the general population as a long-term strategy for weight control or disease prevention is now under increasing scrutiny. Health professionals advise that anyone on a ketogenic diet should undergo regular health monitoring, including tests for blood glucose, cholesterol levels, liver function, and insulin sensitivity.
One of the study’s key takeaways is the importance of looking beyond the number on the scale. While weight loss remains a motivating factor for many individuals who try the keto diet, it is not the only—or even the most important—marker of health. The researchers emphasized that metabolic health includes a range of indicators, such as the ability to regulate blood sugar, maintain liver function, and produce sufficient insulin. These are not always visible or noticeable but may reveal early signs of dysfunction before more serious health problems emerge.
The findings come at a time when ketogenic diets have reached widespread popularity, bolstered by endorsements from celebrities, fitness influencers, and some health professionals. Grocery stores stock keto-branded products ranging from snacks to frozen meals, and online forums abound with testimonials celebrating the diet’s transformative effects. However, the enthusiasm for keto has outpaced the research, particularly regarding its long-term implications. This new study begins to fill that gap, urging more nuanced discussion and better-informed decision-making.
The lead authors noted that while animal models are not perfectly equivalent to human physiology, the consistency of the results across multiple organ systems raises red flags. The duration of the study—spanning nearly the full lifespan of the mice—mirrors years of human dietary behavior and provides rare insight into how a restrictive diet may shape long-term health. Further research is planned to investigate whether similar metabolic disruptions appear in humans following prolonged ketogenic eating, and whether certain populations—based on age, sex, or genetic profile—might be more susceptible to these effects.
For now, the researchers advise a balanced approach to dieting. While ketogenic eating may be useful in some short-term therapeutic contexts or under professional supervision, it should not be viewed as a permanent or universal solution to health and weight concerns. People considering the diet are encouraged to speak with healthcare providers, review their metabolic health history, and establish a plan for ongoing medical evaluation if they choose to continue.
In a broader context, this study underscores the need for critical evaluation of dietary trends. The popularity of diets often rises faster than the availability of long-term research. As a result, consumers may adopt eating plans that appear effective in the short term but carry unseen risks over time. The keto diet is only the latest example of how the intersection of science, media, and consumer behavior can sometimes leave key health questions unanswered until significant risks come to light. With this study, the conversation around ketogenic eating has gained a new layer of complexity—and a renewed call for vigilance, moderation, and evidence-based decision-making.
