Long-Term Low-Carb Diets May Pose Cardiovascular and Metabolic Health Risks, New Research Finds

As low-carbohydrate diets remain a staple of popular weight-loss and lifestyle trends, new scientific evidence is raising critical questions about their long-term safety. A study released in November 2025 has intensified scrutiny of ketogenic diets—commonly known as keto—which prioritize high-fat intake while severely restricting carbohydrates. The findings suggest that sustained adherence to these diets may increase the risk of cardiovascular issues and impair the body’s ability to manage insulin, potentially posing serious long-term health risks.

The research, conducted at University of Utah Health, observed the metabolic effects of long-term ketogenic diets in mice. Over several months, the animals developed signs of fatty liver disease, disrupted insulin signaling, elevated blood lipids, and other markers linked to metabolic distress. Researchers noted that while short-term ketogenic diets can deliver benefits like weight loss and improved insulin sensitivity, prolonged exposure appears to shift the body into a state of chronic metabolic strain. The liver, in particular, showed signs of stress, a finding that raises concern given the central role this organ plays in processing fats and sugars.

These findings are part of a growing body of literature questioning the long-term effects of diets that drastically reduce carbohydrate intake. While short-term benefits of the keto diet are well-documented—including quick weight loss, lower blood sugar levels, and improved triglycerides—nutrition experts have long warned that extended use could come at a cost. High intake of saturated fats, common in many versions of the keto diet, may increase LDL cholesterol (often referred to as “bad” cholesterol) and elevate cardiovascular risk, particularly in individuals with preexisting conditions.

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At the same time, human studies have yielded mixed results. One 2025 study from The Lundquist Institute followed 100 otherwise healthy adults on long-term ketogenic diets. Researchers found that while many participants did exhibit increased levels of LDL cholesterol and apolipoprotein B—both associated with a higher risk of heart disease—there was no clear evidence of arterial plaque accumulation or worsening coronary health during the study period. These findings suggest that the effects of ketogenic diets may vary significantly depending on individual biology, genetics, and other lifestyle factors.

This scientific ambiguity underscores the complexity of human metabolism and the difficulty in making broad dietary recommendations. Some individuals appear to tolerate high-fat, low-carb regimens well, showing improved metabolic profiles and no adverse cardiovascular outcomes. Others may experience increases in cholesterol, liver enzyme abnormalities, and signs of metabolic inflexibility. The key, many experts argue, lies in personalized nutrition—crafting dietary plans based on an individual’s medical history, risk factors, and response to different food patterns.

Despite their popularity, ketogenic diets often eliminate entire food groups, including fruits, whole grains, legumes, and other sources of fiber and micronutrients. This restriction can lead to deficiencies in essential nutrients such as potassium, magnesium, and certain vitamins, particularly if the diet is not well-structured or supplemented. Moreover, fiber—which is limited on many keto plans—is vital for heart health, gut function, and the maintenance of a balanced microbiome.

Health professionals are increasingly recommending that anyone considering a ketogenic or other strict low-carb diet do so under medical supervision, especially if they plan to follow it for more than a few months. Regular monitoring of cholesterol levels, liver function, kidney markers, and insulin response can help identify potential risks early and guide appropriate adjustments. In many cases, a more moderate approach—such as a Mediterranean or plant-based low-carb diet—can provide some of the benefits of carbohydrate reduction without the associated extremes.

The growing body of evidence suggests that while ketogenic diets may be effective for certain goals in the short term, they are not necessarily suitable for long-term use in all individuals. The findings from recent studies call for more comprehensive human trials to better understand the long-term impact of sustained carbohydrate restriction on heart and metabolic health.

In an age where diet trends often dominate headlines and social media feeds, the latest research offers a timely reminder: nutrition is not one-size-fits-all. What works for weight loss or blood sugar control in the short term may have unforeseen consequences over time. A balanced, individualized, and medically informed approach remains the gold standard for long-term health and well-being.