Im 14, and getting zumba dance for xbox kinect, how well and how quick does it wrk?

i'm hoping to lose atleast 20 lbs, im 14 and weigh around 130 lbs, and im 5'2". i got excess fat 'round my midsection and i want to look good in my swimsuit this year. i've always had extra fat around my midsection. and i know the reason fo rthat, im always bored, and when im bored i eat, i try to stop , and i did for about a week, and was excersizing,. but then i got kinda bored and now im back to my old ways. i used to weigh 135, i used wii fit plus for about a month or 2 and i lost around 10lbs. and ive kept that off, but my weight has slowiy increased over 3-4 months since then, im almost up to 130 lbs and i dont want that. i was just wondering if there is also any way to stick to my excersizes and diet/healthy food. i know i'll be able to stick to excersizing with zumba dance bec i love to dance, but how well does it work and how efective is it? im getting it for xbox kinect. (sorry for makeing this so long, i somtimes get a little off track in what im saying)