When is the weight of the body equal to the force of gravity acting on it?

The weight of a body is equal to the force of gravity acting on it only if the body is at rest.
In other cases, body weight and gravity are not equal. For example, if the body is immersed in liquid or gas. In this case, a pushing force occurs, the action of which leads to a decrease in weight.
If a body falls from top to bottom, it has no weight at all until it hits the ground.
In order to increase weight, you need to increase the force of pressure of the body on the support. For example, when you are eating in an elevator, and it slows down dramatically, your weight becomes more than gravity, because you push harder on the floor.