I'm doing track right now at my high school. I'm a sprinter: don't want the weight loss associated with distance. I'm 5'10" (1.78 m) and started at 163 lbs, now at 158 lbs after just week of practice! I wasn't fat to begin with, 31 inch waist. The same now, maybe barely less. I just saw myself in the mirror today and my upper body looked like I never lifted in my life, even though my lower body looked good. Anything I can do to keep weight?