Teens: Can you freely get food whenever you want?

I can't. I have to eat at a specific time - dinner at the latest is 8PM and my parents "close" the kitchen, as they say. It's not because we're poor, we are middle class, pretty good income. It's just my mom thinks I eat too much and I'm getting fat, yet I exercise everyday, have a high metabolism (even my doctor said so!) and I'm on the track team >.>