School meals have been the focus of healthy eating campaigns

The advice, published by the EIS union, calls for a national health promotion training package for all teachers.

It also wants schools to educate parents of pupils who bring packed lunches on how to make them healthier.

The union calls for more funding for breakfast clubs, facilities for teachers to cycle to work, and free access to council gyms for staff.

Ronnie Smith, EIS general secretary, said: "Teachers are busy professionals, but we know that healthy teachers teach better and healthy pupils learn better.

"Our new advice is important to ensure that teachers are fully involved in new developments.

"It will help teachers keep up to date with health issues, and help education managers understand how better to involve staff, including teaching staff."

Daylight and ventilation

Mr Smith said that Scotland was making progress in providing good school meals.

However, other action needed to be taken to address the problem that one in five 12-year-olds was obese, he said.

He called for good daylight and ventilation to be considered whenever a school was built or refurbished.

And he said that good sports facilities must be readily available to all pupils.

Simple things such as fresh drinking water and facilities for preparing healthy meals in staff rooms could help improve the health of teachers, Mr Smith said.