Around may, i decided i should finally do something about my weight, i wasnt terribly obese or anything, iam around 5'10" maybe a little more, 16 years old, at the time i weighed around 183lbs, well about 3 months later i was down at 158lbs, and i remain there today my question is, it seems that whereas before i put on weight fast, now i can eat damn near anything and not gain a pound of weight. I went on vacation this summer, for 2 weeks ate atleast one meal of fastfood a day, next to 0 cardio, and gained about 1 1/2 lbs. My question is (and iam not complaining beleive me heh) what exactly would cause that sort of change in metabolism? It really seems to have sped up. Just curious, thanks.

P.s. thanks for everyone posting stories and tips ect. i've tried diets before, but reading all the posts hear really seemed to help me stay motivated and on the diet.