Underweight children cost the UK’s National Health Service (NHS) about the same per child as those with obesity, according to a new study. The findings were published in JAMA Network Open.

Researchers from the University of Oxford analyzed electronic medical records from more than 268,000 children aged 2 to 15 across England to estimate the NHS’s “excess costs” in the year before and after a child’s weight was recorded as abnormal. They found that children who are underweight — just like those with obesity — tend to use healthcare services more frequently after their weight issue is formally identified.

The study showed that for children with severe obesity, additional NHS expenses reached £472 per year for those aged 4–5. Moreover, only white children showed a consistent increase in healthcare costs across all forms of abnormal weight.

The authors stress that while public health programs often focus on combating obesity, underweight children also require attention, as they similarly contribute to higher healthcare resource use.