A person's weight would be greater at the poles (because he is closer to the center of gravity) than the equator(which is farther from the center about 13 miles).
What Are The Evidence That The Earth Is Oblate Spheroid?
It is a general mathematical law applying to spheroids of revolution. It was initially used to relate the gravity at any point on the Earth's surface to the position of that point, allowing the ellipticity of the Earth to be calculated from measurements of gravity at different latitudes.