Yes.
because they are fat
Yup.
Eating or drinking to much of most anything can make you fat.
If you drink too much, it can. But no it doesn't in and of itself make you fat, only overeating can make you fat.
By pooping too much
no
No pooping
Hitler had pooping problems as a kid, and medicine back then did not help pooping problems
fart like a fat person pooping its own pants
it will make you fat.
eating too much fat would make you fat/obesed
if your pooping green, that is called diaria, diaria can get serious so make sure if your a child that you tell a parent.