The tiny tots at a shiny new pre-kindergarten school and day-care centre in Durant, Oklahoma, are barely aware of the small monitors clipped to the back of their collars where tiny fingers cannot reach.
The pedometers silently record every step, skip and jump the child takes each day.
Widening girths were identified as one of America's gravest health challenges more than 60 years ago and very little has reversed the trend.
A study just published by the Journal of the American Medical Association reveals it is precisely this age group that is setting an example for everyone else. It found obesity rates among 2- to 5-year-olds in America had dropped an impressive 43 per cent over the past decade. For nearly every other age bracket the rates were constant except women over 60, who are getting heavier. It is agreed that a propensity to being overweight as an adult can be established in early childhood years - it is tough not to be pudgy at 40 if you were pudgy at 4, experts say.
It is not known why so steep a drop occurred - about 8 per cent of 2- to 5-year-olds were obese in 2012 compared with 14 per cent in 2003. Declining consumption of fizzy drinks may be a help, as might mothers breastfeeding for longer. Another cause almost surely has to do with awareness initiatives like this one in Durant. And many of these sprang directly from first lady Michelle Obama's Lets Move good nutrition and exercise campaign for kids launched four years ago last week. There is also a proposed revamping of food labelling guidelines so they detail more clearly the calories per serving and raise the size of servings to bring them closer to what people are likely to eat.
The US was relegated to second spot in world obesity rankings by a United Nations report last year which gave the top slot to Mexico, where roughly one third of the population is rated obese and 70 per cent overweight. It said 31.8 per cent of Americans were obese.
The US issued strict new guidelines in January 2012 for school cafeterias, forcing kitchens to offer less carbohydrate-heavy choices and more fruit and vegetables.