The review, which looks at obesity trends over the past 50 years, today and into the future shows that recent data suggests obesity prevalence rates are stabilising across many developing countries, including Australia. However, researchers say the severity of obesity may continue to worsen and lead to an up-swing in the rates of severely obese adolescents. The review also shows that unless there is a sudden and unexpected decline in childhood obesity, large numbers of currently obese youth will grow up to be obese adults with major health risks.
The review, which is published in the Journal of Paediatrics and Child Health, shows that whilst childhood obesity is not a new issue, it has doubled in prevalence since the 1980’s. Prevalence rates of overweight and obesity for five – 15 year old Australian children were steady from 1900 through to 1950 at around five per cent, steadily increasing from 1950 through to 1980 when they sat around 10 per cent. Since 1980 this number has increased to over 25 per cent.
Lead researcher, A/Professor Matt Sabin says the last 50 years has seen unprecedented improvements in the health of children, however this is not the case for childhood obesity.
“Childhood obesity can truly be called a ‘new morbidity’. Childhood obesity has become a global crisis and is one of the world’s most pressing public health issues.”
Despite an increase in obesity and an increase in research in the area, little progress has been made due to the complexity of the issue. Positively, there is growing evidence of the effectiveness of whole-of-school and community-based interventions which promote improvements in children’s eating and activity patterns.
Director of Murdoch Children's, Professor Kathryn North, said conditions such as obesity have increased in epidemic proportions.
“Community based disorders such as obesity are a growing issue and we are developing strategies to treat these problems through evidence based research. However, the best solution to is always prevention. That’s why with our major campaign, Step-a-thon for Kids, we’re focused on disseminating health and wellbeing messages to Australian children from a young age,” Professor North said.
“This national initiative encourages children to keep active and support other kids. Step-a-thon is a way to create and encourage a healthy community, to help address these problems before they begin. Instilling the simple message of getting active while kids are young is vital.”
Currently the Institute is undertaking a number of innovative obesity studies including one which is looking at ‘set-points’ for weight regulation and whether this differs in adults and children.
“Every adult has a weight that is normal for them. This is referred to as their ‘set-point’ for weight. Individuals have been shown to have a physiological protection of this set point, explaining why most obese adults who diet eventually regain weight,” A/Professor Sabin said.
“Our research is investigating whether set points for weight, and their physiological defence, are flexible in early life and whether young children who get on top of their weight will not have this physiological rebound when obesity treatments are finished.”
It is well documented that while most obese adults can lose weight in the short term, the majority can’t maintain their lower body weight in the long term. This is because the body vigorously defends its own set-point for weight, through many interlinking physiological pathways. Several studies have shown that this set point for body weight is strongly maintained, despite variability in energy intake and expenditure. While the set point for body weight in adults appears to be maintained at a relatively stable level for long periods, this trend is not seen in children.
“We have exciting clinical evidence that young children, unlike adults, do not exert the same physiological protection of body-weight, and that it’s possible to easily modify their future weight trajectory so that they don’t grow up to be obese adults. The research study will now test this; if true, then the findings will have major implications for the way in which we prevent and treat childhood obesity,” A/Professor Sabin said.
The study will take groups of young children and adolescents who have either succeeded or not in their efforts to lose weight. Researchers will then give children a test meal and see how their physiology differs in terms of the drive to consume and store calories. Ultimately, they aim to show absolute differences in hormone levels that defend the weight set-point between obese children and adolescents who have lost weight.
Later this year, obesity researcher Professor Melissa Wake will also launch a new project which aims to test the ‘Nudge theory’. The Nudge theory is a concept in behavioural science which argues that positive reinforcement and indirect suggestions to try to achieve non-forced compliance can influence the motives, incentives and decision making of groups and individuals. An example of an implemented ‘nudge’ is rumble strips to slow driver speeds on approaching intersections.
The study will implement a range of home based ‘nudge’ modifications which will tackle established obesity in children and families by continuously supporting healthier eating and activity choices. Examples of nudge interventions include introducing smaller crockery, rimmed plates, a traffic light system for food storage, visible fruit placement, placement of food storage containers and nudge messages on shopping lists, among others.
“Nudge theory directly and continuously targets the minute-by-minute choices that underpin people’s daily behaviour. Combining multiple proven individual ‘nudges’ could sustainably reduce BMI,” Professor Wake said.
In a bid to get Australian children active and support their awareness of the importance of health and wellbeing, Murdoch Children's developed Step-a-thon for Kids. Step-a-thon, which encourages school kids to increase their activity levels was first launched in 2013 and has seen over 30,000 primary school aged children take part.
In two years Stepathon has raised over $1.4 million for research programs at the Institute.