Two beds are in BM 113, baraita says that beis din would leave two beds even for a poor person when taking a loan collateral.
Shmuel explains that he does not know how to heal only 3 sicknesses, including not walking after eating bread.
Interesting, that we not only presume that the poor person will eat bread but also that we need to make sure he exercises.
We can’t take the 2nd bed and just leave him directions to the gym.
Also, it seems that Shmuel stresses these 3 incurable sicknesses are very much along the line of the OP – unhealthy things
people do to themselves. The other two are – bad diet (bitter dates when hungry) and wearing wet clothes.