| In NetHack, a ring of slow digestion will put your natural rate of food consumption at zero. Hunger effects from the other ring you're wearing still apply, as does added hunger from teleportation, etc. Rings of slow digestion cannot be eaten by anything, and slow digestion cannot be gained as an intrinsic.
This is another one of those NetHack items that would be nice to have in real life.
As a side note, I think that "slow digestion" is a misnomer. Digesting food slowly probably wouldn't help much, because nutrients would be absorbed accordingly slowly and you would starve. Slow metabolism or efficient digestion (or even food multiplication) would have been better titles, I think. | 
