We know , weight W = mg; Here m = mass of the object and g = gravitational acceleration. The mass of an object is a constant quantity ; Thus the weight of an object depends on the gravitational acceleration. The higher the gravitational acceleration , the higher the weight of the object. And the gravitational acceleration is less where the weight of the object is less. Since the gravitational acceleration is higher in the polar region. Thus the weight of the object is higher in the polar region. Gravitational acceleration is low in the equatorial region. Therefore the weight of the object in the equatorial region is also less. Gravitational acceleration is zero in the center of the earth. Therefore the object has no weight at the center of the earth.