yeah, Our body's were designed to live on earth. now if you go and live on a simulated planet environment like Jupiter. where we would weigh alot more, Our bodys wouldn't handle it. at first........ but after centurys of adapting. we would eventually become accustomed to the gravity. Its like when Astronauts spend alot of time in space with 0 g's, they have to get used to it, and when they come back to earth they notice a difference. they become a little weaker.
Eh... there's a valid point somewhere in there, but that example is not quite correct. Adaptations would manifest after a while, assuming we somehow survived the conditions to reproduce through hundreds of generations (which definitely could NOT happen with the gravity of Jupiter, but I understand that was just an example). And the astronauts getting weaker isn't the same type of adaptation. Back before they knew that exercise could counteract the atrophying effects of zero gravity, astronauts who had spent relatively long periods in space didn't experience
slight decreases in musculature and bone mass, it was severe and acute. In zero gravity, neither your muscles nor your bones have to bear even the slightest load, so your body just stops putting energy into maintaining them. That's something already programmed into human beings, whereas adapting over hundreds or more generations requires a change in genetic makeup.
Exercise in increased gravity would be okay, so long as it were only exercise. The body is only made to handle a small range of conditions. If you were to live your whole life in increased gravity or unnaturally added weight, your bones and muscles would adapt to a point, but in the end would not be able to cope. (In the case of increased gravity, your organs would also be placed under increased stress, and they can't really adapt at all.)
