I heard that the bodies of astronauts really change if they’re in space a long time. Is this true?
Yes, the long-term effects of living without gravity does show up in an astronaut’s physical appearance. Skylab astronauts found that their legs became thinner, their waists became smaller because internal organs shifted upwards (not a recommended body-trimming technique on earth, however), they got taller by 1/2 to 2-1/4 inches because their spines lengthened and straightened, and the loose skin on their faces rose to give them a high-cheekbone look, while their faces became puffy and bags appeared under their eyes. Things return to normal back on Earth, however.