Its figures show that 21.3 per cent of Scots children born in 1998 were overweight by the age of three and a half, while 8.8 per cent were obese and 4.5 per cent severely so. These findings have prompted child-health experts to demand a “whole system approach” to tackling the country’s weight problem.

Evidence from the Child and Adolescent Health Research Unit at Edinburgh University indicates that young Scots are some of the highest consumers of crisps, chips and sweets in Europe. Surprisingly, they are also among the most active. Dr Candace Currie, the unit’s director, says: “It is not simply a case of boosting exercise in schools. We are not getting the balance right between activity levels and energy consumed. We need to target the problem at a population level.”

Successful efforts have been made to integrate exercise into schools, such as Class Moves from Holland consisting of relaxation and exercises. It is now used by 64 per cent of Scottish primaries. These run alongside SportScotland’s primary sports co-ordinator scheme and the national Active School project.

But Ian Young, who has been seconded to the World Health Organisation to compare young Europeans’ health, is convinced exercise is not enough. He says policy-makers need to take a systemic approach including banning junk-food advertising to children and building recreation facilities in new housing schemes.

He says: “This is not about lack of knowledge - our research shows that 90 per cent of Scottish 12-year-olds know what they should be eating and that exercise is good for them. It requires a cultural change, and the infrastructure to transfer that knowledge into action.”