Keto Diet: New Study Reveals a Potential Long-Term Risk That Has Doctors Concerned

The ketogenic (keto) diet has been celebrated for its rapid weight loss results and potential benefits for certain medical conditions, but new research is raising red flags about its long-term safety. While many have embraced this high-fat, low-carbohydrate regimen, recent studies suggest that the risks may outweigh the rewards for some individuals.

The Celebrated Benefits

The keto diet works by drastically reducing carbohydrate intake, forcing the body into a metabolic state called ketosis, where fat becomes the primary energy source. This approach has been shown to:

Promote significant short-term weight loss
Improve blood sugar control in some people with type 2 diabetes
Aid in managing epilepsy, particularly for those with drug-resistant seizures1 2

Many followers also report reduced hunger and fewer food cravings, likely due to the satiating effects of fat and the suppression of appetite hormones2.

The Newly Uncovered Risks

However, a growing body of research is painting a more complicated picture. A comprehensive review published in Frontiers in Nutrition analyzed over 100 peer-reviewed studies and found that people adhering to keto diets face a significantly increased risk of developing:

Heart disease
LDL cholesterol buildup (the “bad” cholesterol)
Kidney failure
Alzheimer’s disease
Type 2 diabetes
Certain cancers3

Additionally, a recent study from the University of Bath found that the keto diet:

Raised cholesterol levels, especially the types linked to plaque buildup in arteries
Reduced the abundance of beneficial gut bacteria, particularly Bifidobacterium, which plays a key role in digestion and immune function
Decreased the body’s ability to tolerate carbohydrates, potentially increasing insulin resistance if carbohydrates are reintroduced4 5

Doctors are particularly concerned about these changes in cholesterol and gut health, as they are established risk factors for cardiovascular disease and metabolic disorders. The reduction in gut-friendly bacteria may also have broader health implications, including impaired digestion and immune response5 1.

Special Populations at Risk

The risks appear even more pronounced for certain groups. For example, pregnant individuals or those planning to become pregnant may face a higher risk of birth defects and gestational diabetes, even when taking folic acid supplements3. People with chronic kidney disease are also advised to avoid the keto diet, as the high protein load can further stress the kidneys.

A Balanced Perspective

It’s clear that the keto diet can deliver impressive short-term results, especially for weight loss and blood sugar management. However, the potential long-term risks—especially concerning heart health, gut microbiome, and metabolic function—are prompting many experts to urge caution.

As physiologist Dylan Thompson from the University of Bath explains, “The ketogenic diet is effective for fat loss, but it comes with varied metabolic and microbiome effects that may not suit everyone”4. For many, cutting added sugars rather than all carbohydrates may provide fat loss benefits without the same health concerns.

The Bottom Line

If you’re considering or currently following a keto diet, it’s important to weigh the short-term benefits against these newly uncovered long-term risks. Consulting with a healthcare provider or registered dietitian is essential, especially if you have underlying health conditions or are planning major dietary changes. As research continues to evolve, a more moderate approach—such as transitioning to a Mediterranean or plant-based diet after initial weight loss—may offer a safer path to lasting health1 2.