I'm partial to Cliff bars.

A variety of flavors so everyone can get something they like. But even my favorites are not so delicious that I'm tempted to gorge on them if I'm not really hungry. They also don't seem to increase thirst like some bars. They are heavy enough to satisfy hunger for a good time without being too heavy.

A Cliff bar and a half liter or more of water makes a minimalist meal. Two will get me through a day. One in the mid-AM for energy and another shortly before tucking in at night so I can sleep well has got me through a few tight times. Can't say I felt full but it definitely took the edge off and kept my feet moving.

At $1 each, pretty much anywhere, you could do worse. A few retailers give you a discount if you buy a box of six.

The Ricola herbal coughdrops are also a good call IMO. When food and water are scarce soothing the dryness can be very comforting. Lots of relief in a small package.