Another data point for consideration:

A little over a year ago I entered the Army at 5'9", 153lbs.

As an Infantryman, we do fairly rigorous physical training during the work week compared to other jobs in the Army, but it's [usually] not insane. 2 hours every morning. Most days we also go to the gym for an hour or so before being released [honestly, I don't hit it too hard]. On the weekends usually I ride 50-70mi, with the occasional 20mi ride on weekday evenings.

I eat a lot of pizza and burger king. I also drink a few beers almost every night.

One year later, I still weigh 153lbs. To be fair, I have a little bit of a beer gut - all visceral fat, not much subcutaneous.