Ketogenic Diet: What Does the Evidence Show for Long-Term Health?

1. Ketogenic diets improved some metabolic outcomes

The strongest beneficial evidence concerned lower triglycerides, supported by high-quality evidence.

Moderate-quality evidence also supported reductions in body weight and hemoglobin A1c, a marker of longer-term blood glucose control, in specific populations.

These findings suggest that ketogenic approaches can produce clinically relevant short-term metabolic effects.

However, the effects were not identical across different ketogenic diets or patient groups.

2. Some ketogenic approaches increased LDL cholesterol

Potential benefits were accompanied by an important cardiovascular consideration.

High-quality evidence showed an increase in LDL cholesterol with some ketogenic approaches.

An increase in total cholesterol was also among the findings supported by moderate-quality evidence.

This matters because improvements in weight, triglycerides or glucose control should not be evaluated in isolation from other cardiovascular risk factors.

3. Different ketogenic diets produced different results

The review included several forms of ketogenic dieting, and their effects were not interchangeable.

A very-low-calorie ketogenic diet (VLCKD) used in adults with overweight or obesity improved several anthropometric and cardiometabolic outcomes without evidence of worsening muscle mass, LDL cholesterol or total cholesterol in the analyzed trials.

In contrast, a ketogenic low-carbohydrate, high-fat diet (K-LCHF) in healthy participants was associated with reductions in body weight and body fat, but also with reduced muscle mass.

This finding should not be generalized to every ketogenic diet. It does, however, highlight the importance of considering body composition rather than weight loss alone.

4. Long-term health effects remain uncertain

The review provides evidence for changes in intermediate outcomes such as triglycerides, body weight, glucose control and cholesterol.

It does not establish whether ketogenic diets reduce heart attacks, strokes, cardiovascular mortality or overall mortality.

Most trials were simply too short to answer these questions.

The authors therefore emphasized the need for longer clinical trials to determine whether short-term metabolic changes translate into meaningful long-term health outcomes.

A diet that produces weight loss or improves one metabolic marker is not automatically a diet that supports healthy aging over many years.

For longevity, several outcomes matter simultaneously.

Healthy glucose regulation and triglyceride levels are important. But so are LDL cholesterol, cardiovascular health, adequate nutrition, preservation of muscle and physical function, and the ability to maintain a dietary pattern over time.

Ketogenic diets may provide meaningful metabolic benefits for selected people and clinical situations.

At the same time, some ketogenic approaches can adversely affect LDL cholesterol, and changes in body composition also require attention.

Most importantly, current evidence does not tell us whether following a ketogenic diet for many years improves healthspan, cardiovascular outcomes or lifespan.

This umbrella review has an important strength: it synthesized evidence from randomized clinical trials and formally assessed the certainty of the evidence.

However, the evidence base remains limited.

Of the 51 statistically significant associations, only four were supported by high-quality evidence and four by moderate-quality evidence. The remaining significant findings were supported by low or very-low-quality evidence.

The quality of the underlying meta-analyses was also variable. Using the AMSTAR-2 assessment, none received a high-confidence rating, while 13 of 17 were rated critically low confidence.

The short duration and small size of many trials are particularly important when considering longevity.

Different ketogenic diets should also not be treated as a single intervention. Their effects can depend on calorie intake, protein intake, fat composition, the degree of carbohydrate restriction and the health status of the individual.

For healthy adults interested primarily in longevity, current evidence supports some short-term metabolic benefits, but does not establish that long-term ketogenic dieting improves healthspan or lifespan.