What it is: Less than 10% of daily calories from carbs, 10-30% from protein, 60-80% from fat.
Pros: Technically a subtype of low-carb diet, the keto diet is unique: By depriving your body of carbohydrates, you not only force your body to become fat-adapted, but also, if you keep protein low as well, elevate your levels of ketone bodies, which is basically a sign your body is running on fat. The keto diet puts you in a unique metabolic state called ketosis wherein your brain burns ketones instead of glucose—and, in doing so, supposedly leads to clearer thinking. Physically, eating such a high amount of fat significantly increases your body’s ability to burn body fat, according to the study analysis. Research also shows keto athletes have a higher VO2 max, and are able to lose fat without losing strength or power.
Cons: That same study on the perks of being a keto athlete also found those same dieters had a lower exercise economy (how efficiently you use oxygen while moving). And whereas pretty much every other diet offers flexibility in the macro range, eating a few too many grams of carbs or protein will knock your body out of ketosis, so you have to be pretty committed to see the perks of this one. Lastly, the low protein count required to stay in ketosis may be holding you back here: A study analysis in Nutrition, Metabolism, and Cardiovascular Diseases found upping protein on a keto diet by just 5% tripled fat loss.