The ketogenic (“keto”) diet has exploded in popularity over the last decade. Many people use it for weight loss, some for medical reasons, and others wonder whether it can improve athletic performance.

But what does the science actually say?

Here’s a clear, evidence-informed breakdown to help you understand the real benefits, limitations, and considerations of the keto diet — without the hype.

Risks and Side Effects of the Keto Diet

Keto is not appropriate for everyone. Possible risks include:

• constipation

• headaches, fatigue (“keto flu”)

• nutrient deficiencies

• increased LDL cholesterol

• hypoglycemia

• difficulty maintaining the diet long-term

People with diabetes, heart conditions, or other metabolic disorders must consult a healthcare professional before attempting keto due to risks like diabetic ketoacidosis.

Is the Keto Diet Good for Athletes?

The short answer: It depends — and often, not as much as people think.

Research on athletic performance and keto is mixed:

Where Keto May Help

• decreasing fat mass while maintaining muscle

• improving endurance in very low-intensity, long-duration activities

• helping athletes who prefer lower body weight for sport

Where Keto Falls Short

High-intensity and explosive activities rely heavily on carbohydrates as fuel.

Studies show keto can impair:

• sprint performance

• repeated high-intensity efforts

• time to exhaustion in moderate-to-vigorous activity

• VO₂ max performance

For most field and court athletes, strength athletes, and power-based sports, a low-carb diet can reduce performance because it limits available glycogen — the body’s preferred fuel for fast work.

Bottom line for athletes:

Keto may help reduce body fat but does not consistently improve performance, especially for sports requiring speed, power, or high-intensity effort.

More research is needed, but for now, keto is not a universal solution for athletic improvement.

Should You Try Keto?

Keto can be an option for:

• people interested in structured weight loss

• those who prefer high-fat foods

• individuals using it for specific medical reasons

• people who can maintain strict dietary patterns long-term

It may not be ideal for:

• athletes who rely on speed or power

• individuals with certain metabolic or cardiovascular conditions

• people who struggle with restrictive eating patterns

• those who cannot sustain low-carb diets

Always consult a medical professional before making major dietary changes.

Bottom Line

The ketogenic diet can promote weight loss and may improve certain health markers, but it also carries risks and is not suitable for everyone. For athletes, the performance benefits remain unclear, and many sports still require carbohydrates for optimal output.

As with any diet, success depends on individual preference, sustainability, and monitoring.