I have a co-porker who's like that. This 'guy' has never brought in what I would call an actual lunch.  It's always bags of chips, chocolate bars, and bags of candy... with a diet beetus, of course. He'll inhale ~1500 calories of this stuff for lunch, and then get another ~1500 calories of fast food for dinner.  I'm pretty sure this guy has never touched a vegetable that wasn't deep fried and dipped in ranch. Then, of course, he always wonders why he's fat.