Analysis of obesity in children by NHS Quality Improvement Scotland shows that children grow steadily fatter throughout primary until the age of 12 when one in three is now classed as overweight.
Thirteen years ago, the United Kingdom expectation was that around 15 per cent of children at any age would be too fat, 5 per cent of them would be obese and 2 per cent severely obese.
But deteriorating diets are pushing up figures dramatically. Now, 21.3 per cent of children are too heavy by the time they reach three-and-a-half, with 8.8 per cent in the obese category and 4.5 per cent severely obese.
By the age of eight, 23 per cent are overweight and by 12, some 33 per cent are far too heavy, with 18 per cent in the obese category and 11 per cent severely obese.
A year after the Scottish Executive outlined its pound;24 million strategy on healthy school meals, the figures released this week through the 2003 clinical outcome indicators report only reinforce the message that schools are facing an even more daunting task to reverse ingrained and dangerous patterns of eating and drinking.
But local authorities say they are beginning to see some positive signs through joint strategies with health agencies after the Hungry for Success report was published last November.
Highland is persuading all schools to phase out vending machines that push fizzy drinks and sweets and replace them with healthy options as part of its "Your Choice to Healthy Living" campaign. Most are well on the way to removing machines that can earn schools several thousand pounds a year.
The national report ducked an outright ban on vending machines as "unrealistic" and preferred a softly-softly approach. But critics argue that the crisis in children's health demands far tougher Executive action.
Bruce Robertson, Highland's education director, said the healthy options were popular with pupils. Forthcoming fitness figures are likely to be as shattering as the evidence on diet but pupils are responding to the new agenda.
"Our aim is to have pupils as our ambassadors for change when the family goes to Tesco for shopping," he said.
Since Highland's revised policies on healthy eating were introduced in the spring with the help of pound;540,000 from the Executive, school meals are up 12 per cent in primaries and secondaries.
The council now has 30 breakfast clubs and 58 school nutritional action groups to drive home the message. It is further piloting free milk for all primary pupils in Caithness, while the free fruit for children in the early years costing pound;85,000 is proving equally successful. Mr Robertson said the council has also issued advice on balanced packed lunches as part of its new community school initiative.