Weird. When i ate mc donalds id have 2 double quarter pounders large fries and diet coke (yes im that guy) and would still be hungry. Im sure it was a couple of thousand calories but felt like nothing.
When I was young (17, 18) I could eat that stuff like crazy. (And I was like a 160 lb. twink). (Now I'm a 200 lb. twink).
I'd get Big Mac, Qtr. Pounder w/ cheese, McChicken, large frie, apple pie, large soda. (of course I had the serious munchies at the time).

But it was no problem. Now, forget it...