I worked at a dot com that had unlimited free food and drinks and snacks. My coworkers wanted to do a fitness challenge to see who could lose the most body weight by percentage (as to not be unfair to smaller people). I didn't participate because I was already thin but I lost 5 lbs anyways.  All the while working a desk job, drinking heavily (fuck said dot com corporate bullshit), eating bacon, having 3 meals a day and getting a coffee and a snack.  It's not hard at all. To me it's harder to GET fat. I mean for a time I was ordering pizza on the weekend out of laziness and not gaining because the damn thing would last 3 days so that was all I ate.