I agree that a lifestyle change will be more beneficial than a diet routine. It's not simply about eating specific types of foods that won't impact weight gain - it's about LEARNING how to eat, LEARNING what to eat and LEARNING how to maintain good health. Humans are omnivores - we require meat and vegetation in order to have healthy bodies. All those supplements and food restrictions were not meant for our bodies to process. Go back to the basics... meat, fish, poultry, eggs, breads, cereals, fruits, vegetables, etc... stay away from the junk. I did this in high school, in addition to maintaining a high intensity work-outs (joined track and ran 6 - 8 miles a day), and went from 150 to 105 in a year. After 2 months, I didn't even have to think about what I was doing. It all became natural.
When I stopped following my diet in college, it was 2 years before I was back up to 150. It was amazing how lasting the lifestyle was. I'm back on it again... after many years of eating junk. So far, I haven't lost a ton of weight, but I feel better already. And I don't crave sugar or junk food - which was the biggest obstacle. Telling myself I didn't need it was harder than reasoning with myself and saying a little won't hurt. An intial 10lbs was lost in the two weeks that I did that. Now it's all maintaining and work-outs.
But good luck in whatever you do! The idea, I'm assuming, is that you'll be healthier in the end.