There is alot of really good food that is also traditional travelling food, and some of it not all that heavy really.

Wine. Crusty Bread. Cheese.
Currants. Dates. Figs. Honey.
Sausages. Olives. Nuts.

Fortified wine and be watered down before drinking,
so a 1 litre or 2 litre wineskin can go a very long way.