Fundamental physical laws that if you utilise more calories than you eat, you will lose weight.
This 100%. Hence I eat what I like, if I exercise I maintain or lose weight.
When I played football semi pro, I had an awful diet of beer, curries and takeaways, yet I was fit a fiddle.
My weekly diary was something like this.
Monday - Lunchtime 5-a-side, gym after work
Tuesday - Gym after work, football training in the evening, then the pub.
Wednesday - Gym after work, Football training (different team) in the evening, then the pub.
Thursday - Gym after work, straight to the pub, probably a curry as well
Friday - Pub at lunch, straight afterwork, probably end up in a club until 3-4am
Saturday - Match day, clubhouse, pub, club until 3-4am
Sunday - Sunday morning football, pub until it closed, and takeaway on the way home.
And on top of that we also have business lunches and the odd 'quick one' after work.
Even with the massive amount of calories I was consuming, I still had a bit of a 6 pack.
Although I've more of a party 7 these days!