Plus, if you're in a chain, pretty much everyone pigs out, and leaves with a coffee or something.

When I travel with my son for athletic events, there are often crews coming in Sunday night. Those guys outeat the teens, and the teens EAT, and walk back to the rooms with fruit, muffins, etc.

Personally, I would draw the line at taking enough for dinner too. It would be embarrassing for me to be caught with baggies/containers of food. If you're eating a bigger breakfast, taking say a muffin, fruit, yogurt with you, it shouldn't be expensive to buy keep a few groceries in your room. Especially since you don't eat very much.

You might try befriending the breakfast crew and eventually ask what they do with stuff like cartons of yogurt or individual drinks they've put out when the close down. You could also look for chains that put out afternoon cookies or snacks, if you're back in time. I've actually stayed at some when traveling that had a mini munchies happy hour in the evenings a few times a week. Typically it was pizza, few appetizers. Nothing exciting, but was free.