For me, I think a lot of it was just inherited, most of my relatives are huge, most are over 400 lbs, but I got height on top of a big build.
I like my beer but I never saw myself as a big or unhealthy eater. I don't do snacks, chips, sweets, etc. I never ate fast food, and I don't drink soda. I worked an active job, rode a hundred plus miles per week in my younger years yet I was still 300+ pounds.
Now, as I get older, my weight is increasing but I can't imagine eating any less, as it stands now I only get a chance to eat one or two meals a day. My average intake is two eggs and a slice of ham for breakfast with a glass of orange juice, and maybe if I'm lucky a ham and cheese on rye for dinner, on occasion I get a chance to make a real dinner but I rarely have the time.
If I do get a lunch break, its usually just one of those Wawa wraps or a quick salad from the grocery down the road. About once or twice a month I'll go out on a Friday night and have a three or four beers.
I've been gaining size and weight pretty fast over the past year, even though my activity and riding has increased. But at work, my job has me sitting behind a desk 8 hours a day.