Weight loss also causes hair loss, but I'm much happier at 50 lbs lighter. Woo Hoo! FYI, those dieting and seeing excess hair in the drain and in your brush might try Biotin suppliments.
Biotin is good, however a total B complex is better (including biotin). I tried biotin by itself and suffered from restless leg syndrom. When I cut out the biotin and started taking a B complex (with all the B vitamins in it), the restless leg syndrom went away.