We’ve seen several characters talking about Luffy messing up his long term health with his techniques. It started with Gear 2nd. Lucci was like “just because your rubber body let you do that, you still shouldn’t.”
Then the poisoning that should have killed him from Magellan, and Ivankov saving him.
Ivankov told him that his healing hormones aren’t magic, and that it will severely take a toll on his lifespan if he manages to recover from something this fatal. Plus Luffy repeatedly asked Ivankov basically “yo hit me again fam” with his energy hormones, like 2 or 3 times more than Ivankov was comfortable doing.
Plus there were some other things slightly glossed over, like the blood loss on Fishman Island.
I feel like all of this had to be foreshadowing, which I’ll get to after the next paragraph.
Now he’s had multiple days of pushing himself to his limits. He got roughed up somewhat by Cracker, then took two fat beatdowns from Big Mom’s Army and Sanji, then he tried to rip off his own arms, then nearly starved to death, and finally is up against Katakuri. Taking an absolutely ludicrous amount of damage. Like, he’s almost fighting beyond death at this point. I’m not saying he’s going to get killed or anything…
But I think that post-Whole Cake Island arc recovery period will be the time that all of this foreshadowing will come to a head. I just can’t see it not happening, you know? Each blow we’re seeing them land on each other carries too much dramatic weight for it to just get dropped by the wayside once the fight is over.
After this arc calms down, Chopper or someone else will examine Luffy and find that he is in frighteningly bad shape and that years of horrible trauma are catching up to him fast. And something will need to be done about if Luffy doesn’t want to die before he becomes Pirate King.
*Theory by hcnye