Hungry children are seven times more likely than their better-fed classmates to fight, steal, flaunt school rules and fail academically, according to a new medical study.
The study, published in the journal Pediatrics, found, not surprisingly, that 21 per cent of hungry children were dysfunctional, compared to 3 per cent of those who were properly fed.
Researchers drew no conclusion about the reasons hungry children faltered, but hypothesised that hunger caused anxiety in children, distracting them from school.
"Children in households where things are so disorganised that they are not even regularly fed are caught up in that chaos and everything they do is difficult: attending school regularly, paying attention in class and doing homework," said Dr Ronald Kleinman, a Harvard Medical School specialist in paediatric nutrition who conducted the research.
He studied 328 families with children under 12 in and around the city of Pittsburgh. Seventeen per cent of the children were classified as hungry and 49 per cent at risk of going hungry.
"These are children who are repeatedly experiencing hunger, and for prolonged periods of time. Although they may fill up enough at a sitting so that you can't tell they're hungry, those periods of time when they're running on empty is enough to disrupt their psycho-social behaviour," Dr Kleinman said.
In Dr Kleinman's study group, 29 per cent of hungry children required special education, compared with 15 per cent of children who were not hungry. Twenty-five per cent had been forced to repeat a grade in school, versus 12 per cent of their better-fed classmates. And 21 per cent required mental health counselling, compared to 5 per cent of children who were eating well.
Hungry children also were found to be more apt to fight, blame others, disobey their teachers, steal and cling to a parent.
Even among the poor, where there may be other causes for such behaviour, the problems were more pronounced among the hungry poor, researchers found.
The results come even as federal support for low-income children and their families is being scaled back in the United States.
Nationally, an estimated 8 per cent of children - or about four million Americans under 12 - experience prolonged periodic hunger, according to government statistics. About a quarter are considered at-risk for hunger.
In a separate study submitted but not yet accepted for journal publication, Dr Kleinman found that children in Philadelphia and Baltimore who regularly ate breakfast showed improved behaviour, better school attendance and higher mathematics scores than those who didn't.
The United States already spends more than $8 billion a year subsidising meals in school for children, about a quarter of it for in-school breakfasts.