I wonder if it's the same for all of you, maybe, but as I'm
concerned, when I begin to play after say 8 or 10 hrs that my
computer is off I check the health of all my villagers in the
detail screen and then pick up all the one that the health have
droped and bring them to the food bin without never leave them
until their health are full again. This is a very long and bored
way to refill their health sometime more than half an hour to
complete.

Is it is existing an other way to do that? or I do something wrong
somewhere for them to lose health every time I comeback to the
game, the food missing is not the cause they got over 40000 units
or maybe this is normal that I have to feed them in that way?

Villagers can become injured while working, especially the builders and scientists. When a villager is weakened, switching their occupation to a less dangerous one, such as farmer or doctor, will help them recover.

Ok I'll put that tip in practice to see if that will exempt me
to feed them long time for notting.
Thanks.