Forgive me if this seems incredibly obvious to you, but it's pretty hard to eat well while traveling if you don't buy groceries. Some places like Seoul and Taipei have incredibly good convenience stores with a mix of hard boiled eggs, rice balls, sandwiches, nuts, fruits, vegetables, and other hot and cold food in them. But most countries don't - so you're going to eat a lot better if you buy groceries.
I always buy the following:
*Oatmeal: Very easy to cook and nutritious. If you don't have a stove or pot where you're at, just stir boiling water into it. Less water is better. If you add too much water and it's soupy, stir in more dry oats. Microwaving works too.
*Canned tuna: Very nutritious and filling for a small space and weight. Healthy. Protein.
*Fruit: Usually bananas if there's decent bananas around. Other fruit is okay.
*Something to put tuna on: I prefer rice, second choice is good pasta, then cheap pasta or bread.
*Something vegetable-ish: Soup is good, or just vegetables straightup. I like baby carrots to snack on.
*If I'm lifting weights, a bunch of protein. More tuna and nuts if I don't have time or space to cook.
I'm back on Mount Davis in HK, I dig the nature up here so much. After 10 days down in Mongkok and Yau Ma Tei it's good to be out in the wide open space. Thinking of going to the middle of nowhere in the New Territories, but I do like meeting people in the city. Decisions, decisions...