This diet du jour has all kinds of buzz—it melts away pounds, cures brain fog and makes you a better athlete. But are these benefits legit? 

What is the keto diet? 

This low-carb plan is similar to Atkins—no grains, fruits or starchy vegetables—but more fat-focused. On a 2,000-calorie diet, it recommends 150 grams of fat (about 70% of your daily calories), plus 125 grams of protein and just 50 grams of carbohydrates. Following this formula forces the body to burn fat instead of carbs for fuel, a process called ketosis. 

Does it work? 

Research suggests that, yes, this diet can lead to weight loss. But researchers believe that since the diet essentially eliminates an entire food group, it encourages people to naturally eat less. So while it may promote body-fat burning, there’s nothing really magic about keto for weight loss. Protein has also been show to help dieters lose pounds, but that’s not unique to the keto diet, either. And there’s evidence that much of the initial weight loss on this fairly high-protein diet is water weight. Other alleged boons—namely enhanced mental and physical performance—don’t check out. 

What else should I know about keto? 

The diet itself is problematic. It’s super-sensitive (read: restrictive!). A single carb-rich snack can nudge the body out of ketosis. And, while fat isn’t as villainous as we once thought, making it 70% of your diet is extreme, raising concern about heart health. The extra protein could also overtax your kidneys if you don’t drink enough water. 

Another issue: A diet so low in fruits, vegetables and whole grains could be lacking in folate, phosphorus, selenium and fiber. Speaking of fiber, lots of saturated fat plus very low fiber is a recipe for constipation. 

What’s the bottom line? 

Sure, you may lose weight on this diet, but that doesn’t mean that it’s a healthy one. And it’s so hard to maintain that few people stick with it long enough to reap any potential rewards. 

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