Researchers from Oxford Population Health’s Health Economics Research Centre, together with colleagues from the Nuffield Department for Primary Health Care Sciences, have found that underweight children need comparable medical support as those who are severely obese, challenging assumptions about childhood health priorities. The study is published in JAMA Network Open.
The study, which was funded by the National Institute for Health and Care Research (NIHR), provides the first national picture of healthcare costs linked to children’s weight, using NHS electronic health records from more than 268,000 children aged between two and 15 years old across England. It found that childhood weight issues, affecting around 2.5 million children, cost the NHS an estimated £340 million each year.
The study shows that healthcare costs rise sharply after a child’s weight is formally recorded, suggesting that identifying weight issues triggers additional medical support, but only if appropriate services are in place.
The researchers tracked healthcare use in the year before and after children had their weight measured in GP practices, revealing the additional costs ('excess costs') compared to healthy-weight children.
Key findings:
- Four to five-year-olds with severe obesity had the highest excess costs at £472 per year;
- Girls with severe obesity cost more than boys (£253 vs £138 annually);
- Only White children showed clearly higher healthcare costs across all unhealthy weight groups;
- Healthcare use was substantially higher after weight was measured for underweight children, and moderately higher for children with severe obesity.
‘This work suggests we may have been looking at this the wrong way,’ said Dr Olu Onyimadu, lead author from Oxford’s Nuffield Department of Primary Care Health Sciences. ‘It’s not just obesity that drives costs. Underweight children may need comparable support and generate similar costs per capita to the NHS. We need to think about the full spectrum of unhealthy weight when planning services.’
The findings come at a critical time as the government implements its ten-year health plan, which emphasises a shift from treatment to prevention. The research offers NHS decision-makers clear evidence about where to target resources.
Professor Stavros Petrou, co-senior author and NIHR Senior Investigator, said ‘These numbers give commissioners and practices the evidence they need to make the case for weight-management services. Early intervention across the weight spectrum could generate substantial savings while improving children’s health.’
The ethnic variations revealed in the study could help the NHS target support more effectively. White children consistently showed higher excess costs when overweight or obese compared with children from other ethnic backgrounds, insights that could help address health inequalities.
Professor Mara Violato, co-senior author and Professor of Health Economics at Oxford Population Health, added ‘With 27% of children aged 2–15 living with overweight or obesity, plus those affected by underweight, we are looking at a huge opportunity for preventive care. These detailed cost breakdowns by age and sex can help clinical and budgetary service planners identify which children to prioritise.’
The research suggests that once a child’s weight issue is identified, the NHS responds with additional support but that this only works if appropriate services exist. The findings strengthen the economic case for investing in both prevention programmes and weight-management services in primary care.
For parents, the findings indicate that concerns about children being too thin are just as valid as worries about excess weight. The research shows that once weight issues are identified by GPs, children typically receive more medical support, highlighting the importance of regular check-ups.
For commissioners and practices developing business cases for new services, the study provides the robust evidence needed to demonstrate value for money. Because the methodology aligns with UK clinical standards, the findings are directly applicable to NHS decision-making.
The research team emphasised that these cost estimates can now be used to assess whether specific weight-management programmes offer value for money, helping the NHS make informed decisions about which interventions to fund. The researchers note that BMI measurements are not routinely recorded for all children in primary care, and future research will explore patterns over longer time periods.