Diet education has no long-term effect on childhood obesity

An education programme which initially cut the level of obesity in children was no longer effective three years after the intervention, according to a study published online the British Medical Journal (BMJ).

The Christchurch Obesity Prevention Project, also known as the "Ditch the Fizz" campaign, was run for a year in six junior schools in Southern England from August 2001.

The study was commissioned as 10 per cent of the world's school age population is estimated to be overweight. In the UK it has been forecast that by 2010, nearly 20 per cent of boys and 25 per cent girls will be obese.

Janet James and colleagues say studies have shown the relationship between drinking soda and obesity, a link acknowledged by the World Health Organisation (WHO). The authors first said that the study provided some hope that simple interventions could reduce obesity levels.

The researchers now believe these programmes need to be ongoing, if their long-term effects are to be assessed adequately.

In the original study, over six-hundred children aged between seven and eleven were enrolled. The project's primary endpoint was to discourage children from drinking fizzy drinks and promote a healthy diet through four extra health education classes spread over the school year.

Two years after the end of the study the researchers re-measured the height, weight and Body Mass Index of the children, converting them into Z scores, which accounted for the child's age and gender and represents the deviation, compared with an average child of the same gender and age.

The researchers found that the number of overweight children had increased in both groups although the prevalence was still higher in the control group. Three years later, however, this gap was no longer significant.

The study authors concluded: "It remains unclear whether specific interventions or those which focus on all aspects of the diet and physical activity are the most successful. Perhaps the true impact of any school based intervention can effectively only be evaluated if the interventions are continuous."