Is 1/6 G enough for humans to stay healthy?

Question

Micro-G is known to be detrimental to health in the long-term. However, the Moon is at $\frac{1}{6}$ G (while Mars is at ~$\frac{3}{8}$ G). Is $\frac{1}{6}$ G enough for humans to remain healthy in the long term?

(While there are many concerns that make Moon colonization difficult -- i.e. long night/day cycles resulting in large temperature swings -- please focus on the gravity/health question for now.)

This question may be answered in the long term by the Space Studies Institute's "G-Lab" program.

Answer 1

We don't have enough medical data to decide if 0.1667 g is enough or too few. To get enough data we would need hundreds of humans living at 0.1667 g for some decades.

But from what we know now it would be unhealthy to return to 1 g after years at 0.1667 g.

We don't know if a lot of training would be sufficient to keep all bones of the body strong enough for the return to 1 g. What if all bones of the arms and legs got the density needed for 1 g, but some vertebrae are not dense enough?