to build on what psud said - being fat adapted allows athletes to use their stored fat giving them big long term endurance improvements (i.e. running), bonking isn't really a thing anymore.

Volek and Phinney have lots of published papers characterizing athletic performance on fat adapted athletes, but basically they have better access to their fat, and don't under perform vs carb adapted athletes (the default)

The big indirect benefit is exercise recovery, less pain, less time being inflamed.

If your going to jump into keto, i recommend following a well formulated ketogenic guide, the adaptation phase can put some people off. Keep electrolytes up (lots of salt), adjust your diet composition slowly (or you might get diarrhea), and increase fat intake (your trying to become fat adapted, you need fat or you will feel low energy)

Get a CGM ($20) and watch your blood glucose, its the single best way to get started, it turns all your food into a interactive game of keep the glucose low, and there are lots of surprising foods you would think are clean... but aren't.