Always carry food in your backpack no matter what you're doing. This way you'll be able to regenerate health and mana passively, allowing you to heal up if you've taken damage and use spells, or passively work on your magic level.
There are some foods that are more suitable to be carried around like this. The most common are:
- Ham is arguably the best for manasitting. It gives you 360 seconds of regeneration (30%). It's the most cost-efficient if you buy from the store, and is also very easy to obtain by hunting.
- Dragon Ham is quite easy to obtain as many players leave them in spawns or dragon corpses. Not a very good food source for manasitting because it gives 720 regeneration seconds (60%) meaning you will be about half full and must remember to eat again soon (compare with ham - 90% for eating 3 on an empty belly).
- Brown Mushrooms are the best food for hunting or when you will be far from a food source for a long time. Their regeneration per oz is the best of most food that you can purchase, however they are quite expensive compared to other food and harder to obtain by hunting.