What is the maximum amount of gravity humans can comfortably live in?

4.7

To help U understand your question. How many times your weight could U handle. Your weight say 3 times your weight. Hope this helps.

Good question. We do know this. Long term exposure to zero-gravity does bad things to the human body. muscles atrophy and bones become brittle.

Humans have been subjected to high gee forces for short periods of time during spaces launches a high gee maneuvering in jet fighters. At about 5 to 8 gees blood begins to pool in the lower extremities of the human body causing people to pass out. This is countered by gee suites which prevents blood from pooling and keeps it flowing to the brain. These suits are bulky and difficult to move around in. Fortunately, astronauts and pilots are sitting down when that wear them.

The simple fact of the matter is there haven't been any studies on the long term effects of high gee forces on the human body. We are adapted to live in a one gee environment. A high gee environment would likely have the opposite effect of a low gee environment. Stronger mussels and more bone mass, but would this be a good thing? If the heart has to pump harder, would that increase the likelihood of heart attack or stroke? Stronger bones may be harder to break, but they are also more massive and would be more difficult to move around with.

If we did find an habitable planet that we could live on without space suits or domes, I don't believe anything higher than 1.2 or 1.3 gees would be very comfortable. Evolution hasn't designed us to live in those conditions. Could life develop on a 'Super-Earth' with 2 or 3 times the gravity of Earth? Sure, I would imagine it would tend to be rather flat and squat compared to life on Earth. If it were intelligent and attempted to develop a space program, imagine the problems of escaping a gravity well 3 times greater than Earth!

How much weight can you carry around 24 hours a day without getting exhausted or injured?

Planets vary in density so diameter isn't really so much of a factor without mass.

Think about it this way. I am 150 lbs. If I were on a planet with 2gs I would weigh 300 lbs. This would be very exhausting, but I would be able to survive. 3gs would give me a weight of 450. I wouldn't want to move around much under this kind of strain. A productive and enjoyable life would be hard to come by on such a world.

Since any colony would have to put up with amazing hardships in the first decades I would doubt it would survive if the colonists got worn out walking around their dwelling let alone harvesting crops or digging wells. I would say the limit would have to be set at 2 gs and that would be pushing it.

However, as time progressed those with higher bone density and who are shorter will have greater chances at survival so over time the colonists will evolve (very quickly by Earth terms) into forms better suited for the environment. The same goes for many animals. Crops like corn might not fair so well while I would think some crops like soy bean and potatoes would be relatively unaffected, and even tall crops like corn could be genetically engineered before reaching the world to better cope with the high gravity by only sending strains with thick stocks.

I believe humans would adapt, people of earth greatly underestimate their bodies ability to learn for itself. The product of living on a planet with higher gravity may just mean shorter, denser humans.