Doctors and head teachers are calling on the government in England to look at providing free breakfasts to children on free school meals.
They say such a move would help tackle health problems linked with poverty and boost academic achievement.
The call comes from the Royal College of GPs, the National Association of Head Teachers and the Royal College of Paediatrics and Child Health.
A Guardian survey said half of teachers questioned gave food to pupils.
The newspaper's research involved 591 teachers in the UK.
Of those, half said they had taken food in to school to give to pupils who had not had breakfast. One in six said they had given pupils money to buy lunch.
Steve Iredale, a head teacher from Barnsley, said he had taught at six schools and had been aware of this going on in all of them.
"We have all done it, in all types of school. You find a way: keep biscuits in the office, bread in the office. Occasionally you see a distressed child who is hungry."