Researchers from Deakin University's World Health Organisation Collaborating Centre for Obesity Prevention said efforts to address the public health epidemic in Australia were being hamstrung by inadequate and outdated data.

They said the federal government needed to introduce a population-wide program to monitor childhood obesity, which was ''a fundamental component of prevention''.

Writing in the journal Pediatric Obesity, the researchers said the absence of such a program meant Australia was falling behind other countries including Britain in measuring childhood obesity and evaluating strategies aiming at reducing it.

''Obesity is one of the major public health concerns facing Australia yet currently there are no routinely collected data to effectively track the problem,'' they said.

''Monitoring obesity prevalence in children provides important population health data that can be used to track trends over time, identify areas at greatest risk, determine the effectiveness of interventions and policies, raise awareness and stimulate action.''

The researchers, led by Dr Katie Lacy, said opt-out consent - where parents were informed of the program and consent assumed unless they sought to withdraw it - was the best model to ensure high participation rates and obtain representative data. They said fears that taking height and weight measurements in schools could negatively affect children's body image appeared to be unfounded, based on a statewide program in Arkansas in the US.

''In the Arkansas program, it has been shown that there were no significant increases in teasing, weight concerns, embarrassment or unhealthy dieting among adolescents after three years of measurements,'' the researchers said. They said it appeared that problems could be avoided by taking measurements privately and confidential results.

University of South Australia professor of health sciences Tim Olds, who is involved in an anti-obesity program that has taken height and weight measurements from thousands of South Australian schoolchildren, said those taking part in the voluntary program were not given individual data.

''That may avoid the pitfalls of parents overreacting or sensitising children to body image issues. We want population-level data, and this doesn't tell us much about the individual child. Kids go through puberty, and they can go from being really tubby to beanpoles in six months.''

Monash University health sociologist Samantha Thomas said more effort was needed to understand the causes of unhealthy behaviour in children rather than the ''crude measure'' of weight. ''Sometimes we can become really obsessed with numbers on a scale but what we really want to think about and encourage is healthy behaviours. Sometimes weight doesn't reflect whether a kid is engaging in healthy behaviours or not,'' she said.

A spokesman for Health Minister Tanya Plibersek would not say whether the government would consider a program to weigh and measure children in schools.