The thing is, with health, if the effect of you action are not immediat, you are much less likely to do the right thing.

E.g : i know that if a drink a lot of raw milk i generally get a migraine. But it happens 24 to 48 h later. So i still drink milk from time to time because i'm not punished immediatly. It's future me's problem.

I imagine they'd put off eating as long as they could, and then give into the hunger.