This is not from the 70s but ....
Profs: Human race must become Hobbits to save planet
British men 3'3" tall would meet UK carbon pledges
Public-health researchers in London have come up with a new plan to save the planet: wealthy westerners should all reduce by several inches in height by starving their children. This would not only save food, but make people much lighter, meaning that cars and buses would use less fuel.
http://www.theregister.co.uk/2009/04...e_bmi_foolery/