HELP FLEX BELT/ SLENDER TONE USERS!?

I am interested in buying one of these belts because I want to shed about 10-15 pounds. I'm already 'thin' and I workout almost everyday. I'm 5'2", 121 lbs, and 16 years old. I don't want to look anorexic or anything, just toned but lean as well. I'm content with my legs and arms, but my stomach has an annoying pooch. So my question is should I get one of these belts? Which one? And what happens if I stop using them after it has helped me? Will I gain the pounds I lost again and even more?