Childhood obesity an 'exaggeration'

Australia's childhood obesity problem is an "exaggeration" and calls for a junk food tax will do little to relieve the poverty that is its major driver, an expert says.

The rate of childhood obesity among low income families was almost double that seen across middle and high income families, said Dr Jennifer O'Dea from the University of Sydney.

She said a tax on junk foods, as called for by a rising number of health experts, would only place extra financial strain on those families when a "social justice" approach was needed.

And while not downplaying the serious health problems that flow from a life of obesity, Dr O'Dea also said the scale of this problem for Australian children has become increasingly overblown.

"People have to stop exaggerating the numbers about childhood obesity - that's not to say that it is not an issue but you know, hysteria, fear campaigns and exaggeration are not very scientific," said Dr O'Dea, who is Associate Professor in Health Education and Nutrition.

"In children and teenagers, obesity has been stable really since the late 1990s ... and around Australia, it is still about six per cent."

Childhood obesity rates in Australia, as well as in New Zealand, the US, China and many European counties, have barely budged in the past decade.

Dr O'Dea attributes much of the alarm surrounding the issue today to a sharp rise in childhood obesity in the 1980s and '90s, which was forecast to continue but had not materialised.

In Australia, for example, just one per cent of boys and 0.8 per cent of girls were obese in 1985 and this increased to 5.4 per cent and 5.7 per cent respectively in 1996.

More than a decade later, in 2008, obesity in Australian children was found to be 5.3 per cent for boys - a slight decrease - and 5.9 per cent for girls.

"Because childhood obesity increased in the 1980s doesn't mean that it will continue, and in fact it hasn't," Dr O'Dea said, noting the childhood obesity rate appeared to have "levelled off" and a new balance had been reached.

An obese person is generally considered to have a body mass index (BMI) calculation of 30 or above.

Taking in those children near but not at this level, Australia's rate of overweight and obesity roughly doubled from 1985 to 1996 (from about 11 per cent to 23 per cent) but there was almost no movement to 2008 (24 per cent).

These and other figures are contained in new book Childhood Obesity Prevention, a collection of international research on the issue and co-edited by Dr O'Dea with Michael Eriksen.

Dr O'Dea said while the evidence pointed to a plateau, it should be noted the data was not as clear cut as it seemed.

Children went through periods of rapid growth, and those with more advanced muscle development could be deemed to be overweight.

This often included children from a Pacific Islander or Maori background and Dr O'Dea said for many kids "overweight" was not the same as "unfitness".

"Our children have got taller for generations ... our multicultural society in Australia is going to produce lots of children that are different and diverse," Dr O'Dea said.

"That's something that I think everyone needs to understand."

Dr O'Dea said there was one clear trend, of childhood weight problems concentrated at the lower end of the socioeconomic scale.

She points to her research in 2000 that, in a nationwide study of nearly 5000 children and teens, found nine per cent of lower socioeconomic status children were obese compared to only five per cent of children from middle or higher income families.

"It's really an issue of social class," Dr O'Dea said.

"And that's where we need to be very careful to approach it as a social justice issue for these low income communities, and disadvantaged communities, where we see the most childhood obesity."

Serving healthy breakfasts in schools - known to stabilise and improve a child's eating pattern throughout the day - was one key way to address the problem, Dr O'Dea said.

She also called for more of a focus on "assisting physical activity in safe neighbourhoods, in school programs, in after school programs, in non-competitive physical activity where children can be encouraged to play".

"... rather than hitting these already disadvantaged parents over the head with a very big stick.

"We have to avoid this blaming and shaming and finger pointing and focusing on how the parents have failed," Dr O'Dea said.

"I've been very worried that approach will really take hold, and the tax on junk foods is a classic example of that."