I’m 6’2” and weighed about 150 lbs. last year. Now I weigh 180 lbs. and I attribute the weight gain almost exclusively to eating the number of calories I actually was supposed to (chronic under-eater before). It sucked at first, shoveling all the food I could in... but now I’ve tapered off and have maintained 180 for the last twelve months or so with relative ease. You just gotta EAT.