Where, $$W$$ = Weight
$$m$$ = mass
$$g$$ = Acceleration due to gravity
Since, mass is constant all the time, so,
$$ W \propto g $$ ........2
And we also know that ,
$$ g = G \dfrac{M}{R^2} $$
Where, $$G$$ = Gravitational Constant
$$R$$ = Radius of earth
$$M$$ = Mass of earth
So, $$ g \propto \dfrac{1}{R^2} $$ .......... 3
From equations $$2$$ and $$3$$ , we get ,
$$ W \propto \dfrac{1}{R^2} $$
Since $$R$$ is minimum at poles , and weight is maximum at poles and similarly since $$R$$ is maximum at equator, so weight is minimum at equator.
Hence, we weigh more at poles than at equator