I don't know if Oda has stated it for sure, but, Luffy could be eating a lot due to the way his devil fruit affects his body. He is a paramecia, and their powers tend to be all over the place, and somewhat complicated, regardless of the fact that they are the most common fruits to be found. As we've all seen, Luffy is the one who mainly fights the strongest opponents, and overexerts himself to the point of having his body almost break down countless times, and we see a good example of that in Thriller Bark, when he passes out. It's also a habit he picked up as a child, since he used to eat a lot when he lived with Dadan. Anyway, Luffy uses a lot of energy fighting people, especially since he started spamming the hell out of Gear Second and Gear Third, after Eines Lobby, do you have any idea how much energy he's losing? Of course he'd need to eat that much, and it's mainly high proteins, which is why he eats a lot of meat, because his entire body needs it.

I don't know if Oda has stated it for sure, but, Luffy could be eating a lot due to the way his devil fruit affects his body. He is a paramecia, and their powers tend to be all over the place, and somewhat complicated, regardless of the fact that they are the most common fruits to be found. 

As we've all seen, Luffy is the one who mainly fights the strongest opponents, and overexerts himself to the point of having his body almost break down countless times, and we see a good example of that in Thriller Bark, when he passes out. 

It's also a habit he picked up as a child, since he used to eat a lot when he lived with Dadan. Anyway, Luffy uses a lot of energy fighting people, especially since he started spamming the hell out of Gear Second and Gear Third, after Eines Lobby, do you have any idea how much energy he's losing? 

Of course he'd need to eat that much, and it's mainly high proteins, which is why he eats a lot of meat, because his entire body needs it.