A pioneering policy that forces all schools to weigh pupils and send health “report cards” home to parents has halted the spiralling rise in child obesity in Arkansas, say state leaders.

The policy, introduced in the state in 2003, means schools must annually calculate students’ body-mass index (comparing height to weight), said the state’s surgeon general Joe Thompson. “Rather than relying on doctors to do it, we’ve folded it into the school system,” he said. “We now screen for vision and hearing defects and obesity risk.”

Four other US states have since enacted student weight screening legislation, and more are expected to join them.

The weight-screening programme was set up after research found that notifying parents that their children are overweight stings them into improving their children’s diet and encouraging them to exercise.

The reduction in students who are overweight or at risk of being overweight in Arkansas suggests a reversal of the trend towards greater obesity. In 2003-4, 38.1 per cent of all students were overweight, a figure which dropped to 37.5 per cent in 2005-06 Mirroring US-wide trends, the incidence of overweight primary students in Arkansas (excluding those at risk of becoming so) had previously more than tripled from less than 5 per cent in the early 1970s to almost 19 per cent in 2003-4, according to the Centers for Disease Control and Prevention, America’s public health agency. Meanwhile the proportion of overweight secondary pupils rose from roughly 6 to around 17 per cent.

Arkansas governor Mike Huckabee said that the state had “stopped the locomotive train of obesity in its tracks” in arresting a previously spiralling figure.

The crisis is particularly acute among poor and minority pupils. In Arkansas, up to 56 per cent of eight to 12-year-old Hispanic boys and up to 49 per cent of African-American girls aged 10-14 are overweight or at risk of being so.

Arkansas’s weight screening is the lynchpin of an assault on obesity that has seen school canteen staff trained in healthy food preparation - ending practices such as putting extra sugar in food.

The state has also removed vending machines stocked with junk food from primary schools and mandated 30 minutes of daily exercise for all pupils.

Stephen Phillips