Who is the petty one here?

I’m currently living with my parents because I just moved and I’m looking for a place. I’m 21 and I work from 5am-2pm. Sometimes I go running after work or I volunteer at the animal shelter because they have limited people right now. My brother is 42 and lives at home and doesn’t work. Sometimes when I get home from work I make my self something to eat and I’ll make extra for my lunch the next day. I’m trying to maintain my weight after losing about 30 pounds so I’m a little strict on my food. My parents obviously cook but they are on different schedules when they eat and they eat a lot of rice beans red meat etc. It’s happened MULTIPLE times that I wake up to go to work and my food is gone. So I have to throw something together real quick or just go to work and buy something later. Well it’s my brother who eats the left over food. I don’t understand why. I told him that he’s been eating my lunch and he says “you make enough for two? So what’s the problem.” My problem is that it’s my lunch. And he says “well either make enough for 3 or just buy lunch.” I’m trying to save my money to get my own place I don’t want to spend money on lunch everyday. So recently I started hiding my lunches in other boxes... the butter container... or in plain boxes so you can’t see what it is. I guess he caught on to that when he wasn’t seeing my food so he took my lunch that was in a butter container and put butter all the way to the top of it😒 I seriously cannot take it anymore that I’m considering just spending money on a mini fridge and putting it in my room for the time being but my parents think I’m being petty and I can just make my brother some food😐