The number of children admitted to hospital for obesity related problems has quadrupled over ten years.
A study looking into obesity in England and Wales found that 75% of theses problems were to do with asthma, breathing problems during sleep, rather than obesity being the primary problem.
NHS statistics for children and young people aged 5-19 years old were studied by researchers for Imperial College London.
The findings, published in PLOS One, found that the number of bariatric surgery procedures in children and young people rose from one in 2000 to 31 in 2009.
Teenage girls accounted for 75% of the surgeries.
Lead researcher Dr Sonia Saxena said: "The burden of obesity is usually thought to have its serious consequences in adulthood, but we now see it manifesting earlier, in childhood.
"It's clear that rising obesity levels are causing more medical problems in children, but the rise we observed probably also reflects increasing awareness among clinicians, who have become better at recognising obesity."
National surveys in England suggest that around 30 per cent of children aged two to 15 are overweight and 14 to 20 per cent are obese.
Children who are obese have a higher risk of health problems such as type 2 diabetes, asthma, and sleep apnoea.