My parents starve me by only allowing crazy food like hummus and couscous in the house?

I don't like any of that and I throw it away without them knowing. The only time I get to eat is at school or if I secretly spend money from my job on McDonalds. I'm scrawny and get made fun of at school and I'm convinced its because I've been throwing away rice and other crap for 5 years. And I'm not whining. You try and be forced to eat food you don't like for years and years. What can I do about them?