The reviews summarise the results of 114 studies, which involved over 13,000 children and young people.
They are the last two reviews in a series of six that covers surgery, drug therapy, interventions targeting parents only, and lifestyle interventions for children of pre-school age, that will inform ongoing work by the World Health Organization.
The childhood review looks at evidence from 70 studies conducted in over 8,000 six to 11 year olds from Europe, the USA, Canada, New Zealand, Australia, Japan and Malaysia. Most studies compared behaviour-changing interventions with no treatment or usual care.
The quality of the evidence was low but suggests that compared to no treatment or usual care, interventions incorporating combinations of diet, physical activity and behaviour change may have a small, short-term effect in reducing children’s weight and body mass index.
However, the review of adolescents found there here was moderate quality evidence that combinations of diet, physical activity and behaviour change reduce an adolescent’s weight by about three-and-a-half kilos, and low quality evidence that these interventions may reduce body mass index by just over one kg/m2.
These effects were maintained in longer term trials which lasted for up to two years.
More research
The researchers said they could not definitively explain the variation in the results of the studies. They could not find differences in the results when looking at different types of intervention, the setting of the intervention or whether parents were involved in the interventions. Both reviews highlight the need for more research to explore the variation between the study results more fully.
Dr Emma Mead, who led the six to 11 years old review, said: "We need to do more work to understand how to maintain the positive effects of the intervention after it has finished, and understand which interventions work best in lower income countries, and for families from different socio-demographic backgrounds.”
Dr Lena Al-Khudairy, who led the review of adolescents, added: “Approaches that combine several interventions can be effective to tackle overweight and obesity in teenagers, but we still need to know more about what specific components are most effective and in whom, and importantly learn more about adolescents’ views about the interventions.”
Source: Cochrane Reviews
DOI: 10.1002/14651858.CD012651.pub1
"Diet, physical activity and behavioural interventions for the treatment of overweight or obese children from the age of 6 to 11 years. Cochrane Database of Systematic Reviews 2017."
Authors: Emma Mead, et al.
DOI: 10.1002/14651858.CD012691.pub1
"Diet, physical activity and behavioural interventions for the treatment of overweight or obese adolescents aged 12 to 17 years. Cochrane Database of Systematic Reviews 2017."
Authors: Lena Al-Khudairy, et al.