Teachers in New South Wales are being asked to monitor and "dob in" overweight students to welfare workers, as part of a new child protection order.
Nine News Perth reports students will then be given support to help them lose weight with a diet and exercise program.
Speaking to Today, Cheryl McBride from the Public Schools Principals Forum said teachers are "basically" on board with the changes.
"If you are in the position of seeing a child becoming morbidly obese and knowing what the ramifications for that child will be in the future, teachers will perhaps feel a little uncomfortable because t's a new area but they are on board with the child's welfare," she said.
For a child to considered for the diet and exercise program, McBride said they would be "noticeably outside the norm.
She added that preschools have some pretty strong policies surrounding food and teachers would also aim to watch what students are eating at school too.
"We would be watching what they are eating as well as the size of te child," she said.
"It is a sensitive issue but if we look at the bottom line, this is about the child's welfare and we are responsible for those children six hours a day every day.
"But if a parent is perhaps not knowledgeable about nutrition or if the parent ids being guided by the child rather than the other way around or the child is becoming noticeably unhealthy then I think we absolutely have that responsibility to step in."