On this planet, gravity faces many fluctuations, but humans spend most of the time in 1.4-1.5 gravity. During these periods (usually lasting about 5-7 days) I was thinking I'd have them increase salt in their diet to increase blood pressure so their brain would receive sufficient oxygen. I realize that increased salt means decreased calcium which would lead to more kidney stones and risk of osteoporosis. So to counteract this, I would increase the calcium in their diet (also a risk of kidney stones if they take in too much, but hey).
My question is, what other effects would this diet have/what else should I take into account regarding the increased gravity? Would their lifespan decrease(or, for the sake of argument, increase?) Are they more prone (or less prone) to certain diseases/conditions? How would the 1.5g change other organs? Would their brain maybe distort in shape and cause mental changes? I know in 0g eyeballs can become deformed (rounder) and change the person's vision for the worse, but what would the opposite do? Would it be dangerous to give birth, even when mostly submerged in water? The people are shorter (average being 5'5 for men, 5'3 for females) and stronger than we earth beings. What would have more muscle mass entail, other than more eating? Also, would the biological difference between genders cause men to be more susceptible to certain things than women or the other way around? The day cycle is almost 29 hours on this planet, and they sleep around twelve-fourteen hours since they exert more energy. So this would give their bodies more time to recuperate, but then the question becomes would lying around for longer periods of time have detrimental effects as well? And there's a 3 day period where the gravity gradually increases from 0.4g-1.3g before eventually reaching 1.5g. I assume this is better for them as it gives them a ‘break’ and slowly reintroduces them back, but I have no idea.
To specify, my question is not how would they adapt to this environment. Assume that has already happened, I just want how their body currently works to be as accurate as possible. I'm looking for any gap in my thinking and their possible solutions. I realize there is a lot of variables and questions here, but feel free to answer just one of the hundred to help me get things in order.
First post on this site, so apologies if I've made any mistakes.
Edit: I'm aware the gravity situation is not at all accurate, I'm just looking for answers relating to human biology when placed in this circumstance.