it's pretty simple, actually, unless you're in the boss room. if in endless, just fight near a sack, when low on HP, eat an enemy and go sleep, get full HP and fight. if in the boss stage, you just have to be lucky to get good seeds and grind a lot of HP and stomach capacity.
It would be great, it's just that sometimes you have to search for a bag for a long time, if only there was some kind of inventory so that you could not just eat but also store useful things
You can also use "Sneak attacks", since if cleaning a couple secret rooms you would probably has like 3-24 attack power and sneak attacks always choose the highest (24 there) number to deal damage. Nice of boss.