Most of the major negative effects from time in 0g are pretty easy to derive from first principles - like the loss of bone density and muscle mass. The cause is

Most of the major negative effects from time in 0g are pretty easy to derive from first principles - like the loss of bone density and muscle mass. The cause is simply a lack of muscular exertion. In 0g you don't really have much of any recourse against this except lots of mostly elastic based exercise, so astronauts on the ISS spend 2+ hours every single day just exercising, and it still isn't enough. On Mars the deterioration will obviously be lesser. And you also have much easier solutions not only in terms of working out but also passive, like the proposed body suits. Also I'd add that even the less well understood issue like vision decline generally has to do with things 'not going the right way' -- in this specific case 'stuff not going down' increasing the pressure on your ocular region (ever noticed how astronauts all seem to have kind of bloated heads while on the ISS?). On Mars (or any other body with some reasonable degree of gravity) these sort of things won't be a problem.