My daily load going to work usually includes two packets of instant oats, two hardboiled eggs, bread, meat, cheese, cut veggies or fruit, and two 40oz. containers of coffee. I sometimes take in a scone or two too. This supplements the food I leave at work -- I usually keep some grapes, more bread, cream cheese, butter, peanut butter, tortilla chips, salsa, and some yogurt in our kitchen. A mans gotta' eat, and I'm a grazer. I also usually go for a short lunchtime ride, and pick up something to eat and more coffee (I work in a business district with a few options available). I pick up groceries on the way home almost daily to boot.

As I said, a mans gotta eat, it's cold up here, and I am pretty active around those times I'm sitting at my desk (which I do more of than I would like).

As for carrying this stuff... it really depends. Most of it goes into plastic bags I keep recycling, which get put in my panniers (I commute with two Ortlieb Backrollers). I have a thing about trying to buy as little plastic as possible, but sometimes it is unavoidable.