I agree that aesthetically for most people 19-21 looks best...the health benefits of being slightly bigger (but still in the healthy range) kick in once you get a bit older. The extra weight will help you manage an illness like pneumonia or a wicked case of the flu. I hang around 19.5 bmi, but plan on upping my weight till I'm closer to a 23 bmi or so when I'm in my late fifties for health reasons. I can do this because weight is one of the easiest things to control :-) Obeasts fail at such a basic level.