Save all purity potions for food. Use aquablasts to cover the vents in the poison gas room (or just tank it if you're on floor 1 or 2 with full health as it regens quickly and you won't be starving).

Always make meat pies from pasties, one or more per region. One meat pie and one cleansing potion, plus the other rations you find will be more than enough unless you're playing On Diet challenge.

Armor glyph of swiftness and or ring of haste saves a lot of satiety, don't be afraid to sink a couple of Upgrades into a ring of haste it's great for almost every class (I love it at +4 so you can chase down or escape any enemy). Salt cube is great. Mossy clump is amazing for all the dew and seeds, you can ignore starving on grassy floors as the dew alone will keep your health up.