Most science fiction writers have taken to heart the fact that the human body deteriorates rapidly without gravity. Spider and Jeanne Robinson postulate permanent adaptation to weightlessness in the Stardancer trilogy (Although they call it a good thing). C.J. Cherryh bases an entire novel around people needing to spend periodic times in gravity in Heavy Time.
They could all be wrong.
Bear with me here. Fish exist in a buoyant environment. Water tanks are used by NASA to simulate zero gravity. They do have to work against resistance, but not against gravity the way we do. Same goes for whales and dolphins. This implies that it is possible for the cells of an earth-based being to 'permanently adapt to weightlessness'...but what if it is possible for them to fully and reversibly adapt to microgravity?
What if we could switch our cells into a 'buoyancy mode' where they can function without gravity when we went into space, and then back when we land on Earth. No deterioration. No need to be incredibly fit to go into space, no need for exercise up there beyond normal maintenance (if you're a couch potato, you're not going to get fit without a bit of work). No re-adaptation when returning to Earth. What a beautiful pipe dream...
...and it could be within reach. French researchers took a sample of lab rats and...poor rats...suspended them by their tails to simulate the effects of weightlessness. Half of them were given a specific substance. The other half were not.
The untreated rats showed bone loss, muscle atrophy and the beginnings of insulin resistance. The treated rats? Remained perfectly healthy.
Furthermore, the specific substance they used is one that has been consumed, albeit in far lower doses than needed for protection from gravity effects, by humans for centuries. All testing has indicated that this substance helps lower blood pressure and reduce the risk of heart disease. Of course, in the doses required, side effects might show up.
But it does seem as if gravity pills (or patches, or shots) might be possible, thanks to this 'miracle substance'.
What it is might be guessed by the fact that this research happened in France. It is, in fact, resveratol. That's the stuff that makes red wine good for you. And it appears as if it may be practically tailor made to make long distance space travel no longer bad for you.
Think I'll go raise a glass to Bacchus now.