"Amanda Wynne, of the British Dietetic Association, said: "Many things will influence height - including genetics - but nutrition is an important factor."

-- well, yeah. You've got the potential height limitations of the gene pool in question, and then you've got nutrition. These are the only things which affect stature to any great degree.

Japanese are taller than they used to be because they eat more meat but they're never going to be as tall as an equally well-nourished group of, say, Swedes or southern Sudanese.

Americans achieved modern heights early (18th century for whites) because they were well-nourished, and in particular because they ate a lot of meat.

Over several generations, a diet high in animal proteins and fats maximizes your genetic potential as far as stature goes. (It takes generations because there's a complex mechanism which switches genes on and off.) Even American-born black slaves were taller than Englishmen in 1776.

Other things being equal, Nordics will be taller than other Europeans. Things are now roughly equal in terms of diet, so one would expect the Dutch, Scandinavians and northern Germans to be taller than Americans, who include a lot of people with Mediterranean, Amerindian and Balkan backgrounds.

As for obesity, Americans are simply ahead of the curve.

Obeisity rates are shooting up throughout the developed world; South Korea now has a serious problem with it, for example. (While North Korea has killing famines.)