I don't eat a lot while traveling but do drink water constantly. On a much earlier thread (2010?) that talked about
fasting I tried it and discovered I felt very good going without much food for 8 hours or more. But it's
very very important not to get dehydrated.
I know that's not the question you asked
Locally when I'm out and about
I carry a small baggie of home roasted nuts and a biscotti
cookie but I rarely need it even when away from home for 4-8 hours and playing 2 hours of cardio sports. It's really the water that I need most vitally or I go downhill quickly.