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Cochrane reviews show impact of lifestyle changes on obesity

Changes to diet, physical activity and behaviour may reduce obesity in children and adolescents

Ingrid Torjesen

Thursday, 22 June 2017

Two Cochrane reviews, published today, show that a combination of diet, physical activity and behavioural change interventions may reduce weight in children aged six to 11 years and in adolescents aged 12 to 17, but there are limitations in the studies and variation in the results.

The two reviews look at the effects of diet, physical activity and behavioural interventions in treating children with overweight or obesity from six years old to early adulthood. They summarise the results of 114 studies which involved over 13,000 children and young people.

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 majority of trials (65/70) involved both the child and their parents or caregivers.

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-z score (a proxy measure of body fat based on weight in relation to height, sex and age). The researchers know less about the effects of diet, physical activity and behaviour change on self-esteem and quality of life, because few of the trials looked at these outcomes.

Dr Emma Mead, who led the six- to 11-years-old review as part of her PhD at the School for Health and Social Care, at Teesside University, UK, said: “We need to do more work to understand how to maintain the positive effects of the intervention after it has finished.”

The review of adolescents** found 44 completed studies including just under 5,000 young people with overweight or obesity aged between 12 to 17 years. Most studies assessed the combined effects of diet, physical activity and behavioural change interventions, but there was variation in the content and duration of the interventions and their delivery, and the comparators used. There 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. The findings from this review also suggest a moderately improved quality of life but did not find firm evidence of an advantage or disadvantage for improving young people’s self-esteem, physical activity and food intake.

Dr Lena Al-Khudairy, research fellow from the Division of Health Sciences at the University of Warwick, UK, who led the review of adolescents, said: “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.”


* Mead E, Brown T, Rees K, et al. Diet, physical activity and behavioural interventions for the treatment of overweight or obese children from the age of 6 to 11 years. The Cochrane Library. Published: 22 June 2017. DOI: 10.1002/14651858.CD012651

** Diet, physical activity and behavioural interventions for the treatment of overweight or obese adolescents aged 12 to 17 years. The Cochrane Library. Published: 22 June 2017. DOI: 10.1002/14651858.CD012691

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