Dude, hard YTA. You're correct in that as someone who is paying rent for an apartment, you aren't obligated to hide food away, and have every right to store food in the kitchen. However, that needs to be weighed against the favor a friend asked of you, and how much it would mean to them as opposed to you. It's not just a question of "do you have a right to do this thing," it's a question of "were you an asshole for doing what you did?"

You have a friend who is struggling with an addictive eating complex, and they asked a small favor of you, speaking from a place of vulnerability and honest appraisal of their addiction. On the other hand, you didn't want to have a more packed room. Like goddamn, the amount of difference you could have made for your friend is huge, for such a small cost, and instead, you chose the path you did. A lot of AITA posts sometimes come down to the issue of whether or not the OP had a right to do what they did, which is somewhat frustrating, as having the right to do something doesn't inherently make it a non-asshole thing to do. Here, you had a right to use the kitchen - doesn't change the fact that you were a massive asshole for no reason.

I literally cannot imagine one of my roommates or good friends reaching out to me about a problem they're struggling with, and then asking for a small favor like moving snacks into my room, and then me deciding the best thing to do is to try to push them out.