The chief inspector of schools in England will warn this week that parents should not be expecting teachers and schools to police the exercise and eating of children and parents should not ‘abdicate their duties’.

Amanda Spielman says that the issues with the country’s growing obesity crisis lie in children’s homes and parents should not be abdicating their responsibility to schools.

She also warns in her second annual report that schools cannot be a ‘panacea for child neglect or knife crime’.

Ofsted’s annual report will be published this week and will highlight growing worries that by the time children start their primary school careers, nearly one in four youngsters are either obese are overweight.

By the time these children move onto secondary schools, the figure rises to one in three.

‘Teach children about the importance of exercise and healthy eating’

Ms Spielman said: “Schools should and can teach children about the importance of exercise and healthy eating, which is in line with their core purpose and PE lessons should get children out of breath.

“But beyond that, a school cannot take the role of a health professional and, above all, the parents.”

In an acknowledgement of growing evidence that children arrive in reception classes unable to use a toilet, Ms Spielman will say: “This is disruptive for other children and difficult for teachers and has a terrible social impact on those affected.”

The chief inspector will also argue that schools should not be expected to tackle issues of child neglect or gang-related crime since this risks distracting teachers from their core purpose and also fails to resolve problems.

She says that complex matters need to be dealt with those with the ‘correct expertise and knowledge’.

‘School cannot be the panacea for a particular societal ill’

Ms Spielman says: “While a school can play a role in educating children about the dangers of knives, the school cannot be the panacea for a particular societal ill.

“Instead, the prevention of knife crime requires safeguarding partners working together to help protect children from harm, while relevant agencies tackle other criminal activity.”

Ms Spielman’s stance on the obesity crisis and the role that schools can play have been underlined by two studies published this year.

The British Medical Journal has reported that an anti-obesity programme that ran for a year and involved more than 600 primary school pupils in the West Midlands led to no improvements in their health or weight.

Also, Ofsted published the results of a study in July of 60 schools that found no link between the efforts to tackle pupils weight and obesity in a school-led programme to tackle the issue.