I really wanted some cake yesterday, so I ate a big blob of it...and then didn't eat "dinner," because cake was enough calories.  It's literally that simple.  They want to have their cake, and their triple XXL milkshake and KFC and pizza and oh, a friend asked me out for dinner even though I already ate, so I'm just going to eat again.  And then pretend it's weird to eat just an appetizer or a small salad when not hungry and go about ordering a full meal because fatassery knows no bounds.