Because eating meat will instantly supply all your muscles with new power and even increase their mass, before it's even digested. Then you will become at least twice as powerful as before and start growling like a retard, not to mention that it seems that all your bones will heal and you can move normally again! I mean, eating a moth larvae did that much, then what about eating a leg at least 50 times its size? I'm surprised he didn't start fucking floating off the ground as he reached the ultimate enlightenment.
Seriously... This takes cringeworthy to another level, especially since it feels uncalled for given the way the story has been progressing until now.
The shounen bullshit shines way too strongly right now. Please stop it, god dammit. This author truly sucks at this strength and battle crap, it's like every other shounen all over again except that the characters are more grotesque and bloody. But it's still the same ideas. Sigh. This crap wasn't too obvious when the author didn't have the characters fight and try to get stronger. Too bad it's now easy to see it for what it is.