Dieting is just unnatural and bad. It can also lead to orthorexia, an eating disorder where you become so obsessed with healthy eating that you become unhealthy, and orthorexia by proxy where you restrict somebody else's diet, normally a child.

Basically, don't diet. Eat healthy food. Don't deprive yourself...it's better to eat less cake than no cake, for example. Stay as active as your personal body allows.