I'm not the admin, but I wrote part of my Ph.D. Dissertation on astronaut physiology, and they will look a little different after 100-days. They will be taller because their spines decompress in 0-gravity, their skin would be pale, and their bones would be smaller and much weaker. In fact, we risk the first astronaut to walk on Mars to fall and break a hip right out of the gate. This is where exosuits and robotic-assisted suits come in handy.
We are using increased contour makeup to make our astronauts a little aged.
Generally speaking, the astronauts look the same. They are a little taller from the decreased compression on their spines, but like half to 1 inch and not drastic like a 'long-bone' from The Expanse if you've watched that show.
The only other distinguishing characteristic is that the astronauts faces look a little puffier than they do here on Earth from the fluids in their bodies not being pulled downward from their torso and faces as much. Again its a relative difference to their Earth selves and not dramatic.
In general most of the health risks to long duration flight are not apparent in their physical appearance.
Speaking of the health risks, it appears that after more in-depth examination it is clear that astronauts experience lost visual acuity beginning several months into long-duration zero-g flights, that basically there is "evidence of pathological processes undercutting astronauts vision after their missions. Several abnormalities have been revealed, including the flattening of the back of the eyeball, folds in the vascular tissue behind the retina and excess fluid around and presumed swelling of the optic nerve."
In light of the extensive duration at zero-g of the Mars mission presenting this and other health hazards, will design changes likely be given a priority to incorporate some form of spinning habitat or will effort be made to focus on reducing the duration of the mission by using LANTR or other fission-based technology designs?