Authorities in Victoria are now using concerns about extreme obesity as justification for removing children from the care of their parents.

The Department of Health Services has removed at least two children from their parents' care this year over the issue.

Associate Professor John Dixon, from the Baker IDI Heart and Diabetes Institute, says the number is expected to rise in the coming years.

"We've got to understand that as the waistlines of our kids grow, we're going to have these extreme case of obesity," he told News Breakfast.

Professor Dixon says sometimes removing the child is the best option.

"It's not the obesity itself that would lead to a child being removed from their home, but it would be a range of circumstances that would make it difficult for that child to be managed in the best way at home," he said.

"[Obesity can be the result of a] whole range of environmental issues, the food, the lack of transport, all sorts of things.

"But it also can be symptomatic of dysfunctional circumstances... where there's problems; mental illness, siblings with disabilities, that really make family life for some of these children very complex indeed, and produce that rare circumstance where they may be better off out of home for a while.

"Thinking of the rights of the child, the best interests of the child, if it's counterproductive to be at home, then in very rare circumstances that child may be best off not at home."

But he has cautioned against putting the blame solely on parents, saying health services need to be improved to address the problem.

"[Parents] are putting a lot of effort into doing things about it and they don't get a lot of response from our health care professionals and services, etc," he said.

"We have very few services to manage children who are very big."

And he says parents are often reluctant to seek help for fear they might be blamed.

"You can see why parents would be reluctant to seek help when our society doesn't treat their child's problem as a disease, which it is," he said.

"Parents are often reluctant to go to the doctor or paediatrician...for fear they will be classified as being negligent or not looking after their children very well at all.

"We need to give good practical family advice to prevent obesity and to treat it when it's there."