A skyscraper barely changes your weight
Gravity weakens with distance from Earth’s center. At the top of a skyscraper, you are slightly farther from the planet’s center than someone at street level, so Earth pulls on you a little less strongly. The difference is real, but for an ordinary building it is far too small to feel: your body does not stretch, float, or undergo any meaningful physical change.
The reason is scale. Earth is thousands of miles in radius, while even a very tall building adds only a tiny amount to that distance. Because gravitational strength falls off gradually with distance, moving up a building changes it by only a fraction of a percent.
The air is a separate question
Outside, air pressure generally decreases with altitude because there is less air above you pressing down. But a skyscraper’s upper floors are enclosed, and ventilation and climate-control systems regulate indoor air. They do not expose occupants to the thin air found at comparable heights in the open atmosphere.
So the main bodily difference is essentially imperceptible: a person on a high floor weighs an immeasurably tiny bit less than the same person at ground level. The building changes your distance from Earth, but not enough to make your body notice.
