0114 GMT February 20, 2019
England's chief inspector for schools will argue the answer to the obesity crisis lies in the home, and parents should not "abdicate responsibility", BBC reported.
Neither can schools be a "panacea" for knife crime or child neglect, she will add in her second annual report.
Two studies have this year queried the benefit of school anti-obesity schemes.
In February, the British Medical Journal reported that a year-long anti-obesity program involving more than 600 West Midlands primary school pupils yielded no improvements.
And in July an Ofsted study of 60 schools found no link between efforts to tackle obesity and pupils' weight.
Spielman, who will present Ofsted's annual report on Tuesday, will highlight concerns that – by the time they start primary school – almost a quarter of children in England are overweight or obese.
This rises to over a third by the time they move on to secondary school.
"Schools can and should teach children about the importance of healthy eating and exercise in line with their core purpose; their PE lessons should get them out of breath," she will say.
"But beyond that, schools cannot take over the role of health professionals – and above all parents."
Highlighting the growing evidence of children arriving at reception unable to use a toilet, she will add, "This is difficult for teachers, disruptive for other children and has a terrible social impact on the children affected."
Spielman will also argue that by expecting schools to tackle gang-related crime or child neglect, society risks not only distracting them from their core purpose but also failing to solve the problems.
Such complex matters need to be dealt with by those with the correct knowledge and expertise, she will argue.
"While schools can play a role in educating young people about the danger of knives, they cannot be a panacea for this particular societal ill," she will say.
"Instead, preventing knife crime requires all local safeguarding partners to work together to protect children from harm whilst the relevant agencies tackle criminal activity."
Spielman’s comments represent a blunt message to ministers keen to tackle topical issues by placing more responsibilities on schools even as they face cuts to resources in the face of austerity. Over the summer the Home Office issued lesson plans for children as young as 11 about the dangers of knife crime, which would involve them being told it is a “myth” that they will be safer with a weapon.
Plans were also announced to educate teachers on related slang.
British Minister for Children Nadhim Zahawi said the lesson plans would “help illustrate the real impact of knife crime on young people’s lives” and that schools “up and down the country are taking advantage of them”.
With evidence that the average age of knife crime victims is falling, some National Health Service (NHS) doctors have called for school exit times to be staggered to reduce the chances of clashes.
There have been major concerns about teachers’ workloads and the impact on the numbers staying in the job. The Department for Education recently pledged to ease pressures on teachers in England after a report blamed an “audit culture” for causing stress among staff.