The study highlights health care costs associated with both underweight and obesity in children

The NHS incurs an estimated £340 million in extra healthcare costs every year due to weight-related health problems in children, but it is not just obesity that generates costs. New research from the University of Oxford shows that underweight children need comparable medical support to those who are severely obese, challenging assumptions about health priorities in childhood.

The study, published and funded by the National Institute for Health and Care Research (NIHR), presents the first national picture of children’s weight-related healthcare costs based on NHS electronic health records of over 268,000 children aged two to 15 years across England. It found that childhood weight problems – affecting around 2.5 million children – cost the NHS an estimated £340 million a year.

Importantly, the study shows that health care costs rise dramatically once a child’s weight is formally recorded, suggesting that identifying weight problems triggers additional medical attention – but only if appropriate services are provided.

Key findings with implications for practice

The study monitored health care use in the year before and after children’s weight was measured in GP practices, revealing additional costs (‘excess costs’) compared to children of normal weight:

• The highest additional costs are £472 a year for children aged four to five with severe obesity
• Severely obese girls cost more than boys (£253 compared to £138 per year)
• Only white children showed significantly higher health care costs across all unhealthy weight groups.
• After weight measurement, health care use was significantly higher for underweight children and moderately higher for severely obese children.

This work suggests that we may have been looking at it the wrong way. It’s not just obesity that generates costs. Underweight children may require comparable support and generate similar per capita costs for the NHS. We must consider the full spectrum of unhealthy weight when planning services.”

Dr Olu Onyimadu, lead author from the Nuffield Department of Primary Care Health Sciences, Oxford

The findings come at a critical time as the government implements its 10-year health plan, which emphasizes moving from treatment to prevention. The study provides NHS decision-makers with clear evidence on where to direct resources.

Professor Stavros Petrou, co-author and senior NIHR researcher, said:

“These figures give commissioners and practitioners the evidence they need to make the case for the need for weight management services. Early intervention across the weight spectrum can generate significant savings while improving children’s health.”

The ethnic differences revealed by the study could help make NHS target support more effective. White children consistently showed higher excess costs of being overweight or obese compared to children from other ethnic groups – insights that could help address health inequalities.

Professor Mara Violato, co-author from Oxford Population Health, added:

“With 27% of children aged 2-15 years overweight or obese, as well as children who are underweight, we see a huge opportunity for preventive care. These detailed breakdowns of costs by age and gender can help clinical and budgetary service planners determine which children should be prioritized.”

What this means for families and the NHS

The study suggests that once a child’s weight problem is identified, the NHS provides additional support, but this is only effective if appropriate services are in place. The findings strengthen the economic case for investing in both preventive programs and weight management services in primary care.

The study results indicate that for parents, concerns about their children being too thin are as important as concerns about being overweight. The study shows that when GPs identify weight problems, children tend to receive more medical support – from nutritional advice to mental health services – underscoring the importance of regular check-ups.

For commissioners and practitioners developing business cases for new services, the study provides the solid evidence needed to demonstrate value for money. As the methodology is consistent with UK clinical standards, the findings are directly applicable to NHS decision-making.

The research team highlighted that these cost estimates can now be used to assess whether specific weight management programs offer value for money, helping the NHS make informed decisions about how to fund interventions. The researchers note that BMI measurements are not routinely recorded for all children in primary care, and future research will examine patterns over longer periods of time.