Gastric band surgery is only offered to obese patients as a last resort, and children or teenagers must meet a strict criteria before they are even considered for the procedure. To qualify, the NHS Gastric Band Criteria is that they must have a body mass index of more than 40, have reached puberty, have first tried to slim through dieting or exercise, and have a full understanding of the psychological implications.

 Some parents, when they come to us, have the idea that if their child has the surgery it will act like a magic wand

But even with these stringent rules, Government figures show the number of young people under 19 having a gastric band on the NHS doubled between 2007 and 2013, when more than 200 children had the surgery.

The Gastric Band Cost per operation for the NHS is more than £7,000.

Official statistics from the National Bariatric Surgery Register, which is compiled from surgeons’ reports, reveal that the 12-year-old boy is the youngest child to have been fitted with a gastric band within this group, although it is not recorded if the operation was publicly or privately funded.

NHS statisticians said the youngest patient they had on record for bariatric surgery paid for by the Health Service was 13.

However, many surgeons argue that the stomach bands could save the NHS money through reducing levels of obesity and associated illnesses such as type 2 diabetes, which are estimated to cost the Health Service £5 billion a year.

Dr Lucy Stirling, a clinical psychologist at King’s College Hospital, said parents whose children are facing gastric band surgery can fail to take responsibility for their child’s weight issues.

She said: ‘Parents can be in denial of the part they have played.

‘But children need to be brought up to eat in such a way that they’re nurturing their body rather than slowly damaging it.’

Paediatric consultant Ashish Desai added: ‘Some parents, when they come to us, have the idea that if their child has the surgery it will act like a magic wand.’