Attempts to tackle to tackle childhood obesity at an early stage through offering behavioural, parent-focused interventions alone do not solve the problem.

That is the conclusion of a study – which the authors claim is the most comprehensive individual participant data meta-analysis ever conducted in the field – that was published last week (10 September) in The Lancet.

The lead author is Kylie Hunter, who is based at the University of Sydney’s National Health and Medical Research Council Clinical Trials Centre. The large international team says it used gold-standard methods but found no evidence that parent-focused obesity prevention interventions affect child BMI Z score at age 24 months (or within six months either side) or most of secondary outcomes. [BMI Z scores are used to classify the different degrees of weight status in children and adolescents].

Dr Hunter and her colleagues conclude: ‘Our findings indicate that existing early, behavioural, parent-focused interventions alone are insufficient to address childhood obesity.’

Global problem of obesity

Globally, some 37 million children under five years are said to be overweight or obese, with childhood obesity having major lifelong health impacts. To prevent the condition, many authorities argue that it is crucial to intervene early, before overweight or obesity first develop in early childhood.

The World Health Organization recommends the adoption of a lifelong approach to reduce the risk of obesity, starting during pregnancy. It calls for the provision of guidance on healthy diet, sleep and physical activity in early childhood for parents/caregivers.

In response, many governments have made early parent-focused programmes a key strategy for obesity prevention.
Examples include community parenting classes, home visits or sharing information via SMS/email/app with a focus on building parent’s skills and knowledge on topics such as nutrition, physical activity and sleep.

However, there has been limited evidence on the effectiveness of such programmes, putting policymakers in a challenging position and resulting in decisions to implement potentially resource-intensive programmes, despite gaps in the evidence. 

In comments made to publicise the study findings, Dr Hunter said: ‘Obesity is in large part driven by environmental and socio-economic factors that individuals are unable to change. Parents play a vital role, but our study highlights that they cannot be expected to reduce childhood obesity levels alone.’

Dr Hunter added: ‘Broader, coordinated action across society is needed to make healthy choices easier for everyone, regardless of where they live. Alongside support for parents, we need to see coordinated policies which improve affordability of healthy foods, increase access to green spaces, and regulate unhealthy food marketing to tackle childhood obesity.’

More than 70- researchers involved

The authors formed a global collaboration (TOPCHILD) of more than 70 researchers across 47 institutions, combining data from 31 trials set across 10 countries. Investigators from all trials worked together and shared their individual participant data resulting in a large dataset of 28,825 participants to examine the impact of obesity prevention programmes designed to help parents foster healthy nutrition, sleep and activity patterns in their toddlers.

‘Alongside support for parents, we need to see coordinated policies which improve affordability of healthy foods, increase access to green spaces, and regulate unhealthy food marketing to tackle childhood obesity’ [Kylie Hunter, lead author]

To be included in the meta-analysis, programmes needed to commence sometime between pregnancy and 12 months of age and to measure a child weight-related outcome. The authors also disentangled detailed information on the content and delivery of interventions in a complementary piece of research led by Flinders University.

Of the 31 trials contributing data, there were 17 trials with individual participant data which assessed BMI at approximately two years of age (a total of 9,128 participants). These trialled different intervention approaches included

• a trial in the UK assessing a programme in which eight weekly sessions were delivered in children centres to groups of eight to 10 parents to target behaviours including food provision and movement
• an Australian trial in which women with their first child received eight home visits spread over two years with advice on topics including breastfeeding, timing of introducing solids, screen time and physical activity
• a trial in the US in which primary-care providers set dietary, physical activity or screen time goals with parents, aided by low-literacy booklets, at seven visits from two to 18 months

With a high level of certainty, the meta-analysis found that the early childhood obesity prevention programmes had no effect on BMI of the children at approximately two years old.
 
All children need ‘healthier environments’

Senior author Anna Lene Seidler, who is based at the University of Rostock in Germany, said: ‘There are several potential explanations for why current parent-focused programmes to prevent obesity in toddlers are not effective. One reason could be that the first year of a child’s life can be overwhelming and stressful for parents, leaving them with limited capacity to fully engage in behavioural changes. Once children enter broader social settings such as early childcare and school, programmes which create healthier environments for children directly in these setting may be more effective.’

Professor Seidler added: ‘Additionally, the families most affected by childhood obesity – often those in lower socioeconomic groups – are also the least likely to be reached by parent-focused early programmes. They often simply do not have the resources or time to attend and adhere to these programmes, particularly in the current cost of living crisis. Policy level changes aimed at creating healthier environments for all children are more likely to reach these families.’

Study limitations

Among the study’s limitations, Dr Hunter and her colleagues acknowledge that seven of the 17 trials were rated as having a high risk of bias due to missing data and/or that data were missing at different rates for participants in the intervention group compared to those in the control group. However, when these studies were excluded from the analysis, the results remained the same.

To access the full version of the article – titled Parent-focused behavioural interventions for the prevention of early childhood obesity (TOPCHILD): a systematic review and individual participant data meta-analysis – see: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)01144-4/fulltext

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