A few years ago in Bangkok I noticed some children emerging from school. To judge by the chauffeured cars that were waiting for them they were the children of the elite. They were all guzzling fast food and drinking sweetened drinks that they had bought immediately after being let out. Not surprisingly, many of them were fat, very conspicuously so in a nation as slender as the Thais. 

This seemed to me to be a bad augury, and so it has proved. The epidemic of obesity is now worldwide: people the size of stranded whales are now to be found every-where, albeit in still differing proportions of the population. Robert Lustig, a paediatric endocrinologist with much experience of