OMG--Sorry, yeah, I know how you feel. I'm swearing at your dad over and over again right now, my problems feel like nothing.
Yeah, I told my dad I was gay (I know it's a bit different, but I can relate to you a lot, and I'm using my story to tell you how to get them in trouble) in March '06, I'm also 15 , by the way, and ever since he's basically hated me. He tried to beat me up and the police were like, "Oh, well, we'd have to take you away, that's all we could do, blah blah blah." I live in Utah, and they're really into family, so as dirty fag *sarcasm*, I should get taken away. Well, actually, they'd have to take away all of the kids, which my mom wouldn't let, and then tell them to take my dad, but yeah, anyway---
In November, my dad freaked out when he heard me talking about homosexuality to some family members at Thanksgiving dinner. He started ranting to my mom in their bedroom about how awful I am and blah blah. Then a few days later, I was on the computer and he started telling me I can't use any of our computers (I use my mom's work laptop now) and I am useless and should die. I didn't deserve anything and I should drop dead and die if I have any honor. I told my counselor at school, she called child services and they told my dad he can't talk to me at all. (Though my parents are married, so it is awkward at times.)
Anyway, you really need to fight it. If you're mom is lying, then you need to do as much as you can to get Child and Family Services involved. They will get very involved. That whole food thing is illegal nation-wide, the longest you can be not allowed is 2 meals and it has to be in a 24-hour period.
Anyway, if you're really a human punching bag, then show bruises to your school counselor and it should get taken care of within a day or 2.
I hope it all turns out okay, e-mail me at davinci.ian@gmail.com if you ever want to talk. ^_^