If you are highly active and have a low bodyfat percent, then you are just catabolizing your own muscle by fasting, and you become very injury prone. There's no upside.

You seem out of touch with the scientific literature, and have hand-waved all the real health benefits I've listed.

Leading figures like Peter Attia, Tim Ferriss, Ben Greenfield, David Sinclair, Kevin Rose to name a few, all pro fasting, all in top shape/low body fat.

> and you become very injury prone

No, you become temporarily weaker, and that's only if you're fasting multiple days. It's recommended you work out during fasts... your body remains anabolic to muscle (barring other variables like elevated stress).

With the exception of Ben Greenfield, none of these people seem to have a sports science background. In the realm of athletics, things like intermittent fasting and keto diets are something of a meme. Some people do advocate for training with depleted muscle glycogen first thing in the morning, but there's no consensus that this does anything.

Autophagy for me is my muscles eating themselves for energy. Not healthy, and it feels like being beaten.