Professor Elizabeth Waters writes:
Childhood obesity can be prevented. If effective programs are implemented widely, it would make a significant impact on the lives and outcomes for children, adolescents, and adults.
The personal and population level costs associated with child and adult obesity include diabetes, cardiovascular problems, cancers, social concerns, and significant costs to health and other sectors.
We have just completed a major review of the evidence base to provide a contemporary synthesis of the range of strategies being implemented and evaluated worldwide to answer the million dollar question: do they work?
We found that childhood obesity prevention intervention programs, implemented through healthy eating and physical activity policies, programs, and workforce development in children’s settings, do work, reducing children’s BMI and risk of obesity.
This review was an update of the Cochrane Review on childhood obesity prevention interventions, first published in 2001, and last updated in 2005. In 2010, it was still the second most downloaded review on the entire Cochrane Library, highlighting that solutions to childhood obesity remains a major area of interest worldwide.
The Cochrane childhood obesity prevention intervention evidence review now includes 55 studies, and a range of meta-analyses, which provides compelling evidence that consistently applied policies and strategies to increase healthy eating and physical activity would make a significant impact in reducing the prevalence of childhood obesity, and stem the tide of increasing rates observed and predicted to continue to increase around the world.
Studies varied in terms of what programmes they evaluated for preventing obesity and the degree of benefit they identified. Nevertheless, taken together the review indicates that the interventions had a positive impact on average bodyweight.
Given the range of programmes included in this review, it is hard to say exactly which components are the best, however the features common are those that seek to change environments and norms, rather than just the behaviour of individuals, such as:
• Including healthy eating, physical activity and body image in school curricula
• Increasing the number of opportunities for physical activity and the development of fundamental movement skills each week in children’s settings
• Improving the nutritional quality of food supplied in children’s settings, particularly schools
• Creating environments and cultural practices within settings that support children eating healthier foods and being active throughout each day
• Professional development and capacity building activities which help to support teachers and other staff as they implement health promotion strategies and activities
• Supporting parents to make changes at home that encourage children to be more active, eat more nutritious foods and spend less time in screen-based activities. The overall effect size observed between interventions and controlled groups was -0.15 kg/m2, approximately 0.4-1.6% reduction in children’s BMI.
The implication of this is quite remarkable – were these programs able to be implemented across the population, we can be confident that this would translate into a reduction in body weight that would have substantial effects on consequent health burdens.
Whilst estimates haven’t been conducted for children, estimates of 1% reduction in BMI for adults would avoid up to 2.1-2.4 million incident cases of diabetes, 1.4-1.7 million cardiovascular diseases, and 73000-127 000 cases of cancer in the US.
Of course it is only possible to understand the benefit or harms of programs through well designed and conducted evaluations of programs, and we can only understand whether these programs are sustainable through long term evaluations and monitoring.
This review restricted its scope to studies with controlled evaluations and unfortunately, despite searching extensively in the published and unpublished literature, we were unable to find evidence that initiatives conducted by industry to improve healthy eating environments or menu’s had been evaluated using these rigorous evaluation methods.
However, the review found compelling evidence that food environments and eating policies that removed junk food and soft drink from menus resulted in reduced weight in children. It also demonstrates the value of increased investment in physical activity programs, and the need to invest in people and professional development to help evolve and sustain strategies.
Effective components now need to be embedded as standard practice within settings, and across sectors. Without it, childhood obesity is predicted to continue to rise, from 25% to 33% in 2025 in Australia alone, along with consequent health burdens, healthcare costs, and poorer long term outcomes.
With this relatively efficient investment across the population, we now have confidence that health outcomes will improve for kids, their families, and the wider population.
• Elizabeth Waters is the Jack Brockhoff Chair of Child Public Health and Director, The Jack Brockhoff Child Health and Wellbeing Program, The McCaughey Centre, Melbourne School of Population Health, The University of Melbourne
Full citation: Waters E, de Silva-Sanigorski A, Hall BJ, Brown T, Campbell KJ, Gao Y, Armstrong R, Prosser L, Summerbell CD. Interventions for preventing obesity in children. Cochrane Database of Systematic Reviews 2011, Issue 12. Art. No.: CD001871. DOI: 10.1002/14651858.CD001871.pub3.