Genetics ftw. I eat 2 large bags of chips a week - but other than that, I eat healthy choices. Last time I got my body fat checked, I was @ 8%. I was 5'9 @ 155lbs. I'm actually down to 150lbs now. I generally eat 3500-4000 cals a day, but I'm pretty active. Gym 3 times a week, bike almost daily and run at least once a week.

My entire family is all small (at least my mom's side where I got my metabolism genes) and eat don't eat as healthy as I do. I can lose weight very easily but gaining is very hard for me.