Do cleansing programs help you lose weight?

I'm 17 years old (male) and around 6'0 and weigh 242. So I wanna lose around 100 pounds and also wanna lose acne but my weight has become a much bigger issue than acne now. I really would like to reach my desired weight 150 - 170 not over 170 by 2009. I was gonna water fast but I hear of all the horror stories so I'm starting to reconsider. I am willing to give up soda, junk food, all that crap forever. So would what would be a good diet for me? I'm gonna post a more in depth questions with pics of me on wanting to look better later. Just wanna know what I can do to lose weight right now.