I feel so guilty after eating that I actually consider making myself sick sometimes?

I know it's unhealthy and crazy....but I just feel so bad after eating junkfood. I weigh 120lbs but I look like I weigh 150! I just hear how it makes you lose weight dramatically. I know it's stupid...but does anyone have any advice? A way not to feel so guilty? Or something to help me not to indulge?