The explosive rise in admissions from 872 to 3,806 occurred in the space of a decade between 2000 and 2009.
Over the whole 10-year period, a total of 20,885 young people were treated in hospital for obesity-related conditions.
Nearly three-quarters of cases involved problems complicated by being overweight, such as asthma, breathing difficulties during sleep, and pregnancy complications.
Teenage girls accounted for the biggest rise in obesity-related hospital admissions. In 2009, obesity is believed to have contributed to complications in 198 pregnant girls.
bariatric surgery procedures conducted to help children and young people lose weight also saw a sharp rise, from one per year in 2000 to 31 in 2009.
Three-quarters of the patients were teenage girls. Bariatric surgery is a drastic obesity remedy that involves shrinking the stomach with a gastric band, removing part of the stomach, or re-routing the small intestine to a small stomach pouch.
Researchers from England's Imperial College London analysed NHS statistics for children and teenagers aged five to 19 who had a written record of obesity. Their findings are reported in the online journal Public Library of Science ONE.
"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."
Surveys suggest that around 30% of English children aged two to 15 are overweight and up to a fifth are obese.
Children who are obese are more likely to suffer health problems such as Type-2 diabetes, asthma, and sleep apnea - a condition that causes interrupted breathing during sleep - researchers said.
In their paper, the scientists wrote:
"Our findings support emerging evidence that the childhood obesity epidemic may lead to substantial problems of obesity-related disease much sooner in children and young people's lives than previously expected."
"With levels of admissions for obesity-related diagnoses rising, there is likely to be increasing demand on health services and also greater use of more radical interventions, such as pharmacological or surgical treatment, as part of efforts to address the increasing trend of obesity that threatens the lives of many children and young people in England and globally."
"I'm not surprised by this leap, and I won't be surprised if in five years we're talking about another significant rise."
"When it comes to obesity we have taken our eyes off children to such an extent that they are now completely unmonitored and left to get on with it."
"The medical profession is not really paying too much attention to them. A lot of these young people are completely unaware that piling on the pounds will not only make them fat but give rise to these other conditions."
He said the "real tragedy" was obese schoolgirls becoming pregnant. "Girls are not only getting fat, but getting pregnant," said Mr Fry.
"The result is not only distressing for the girls but threatening for their children." Pregnancy complications linked to obesity included gestational diabetes, high blood pressure, the dangerous condition pre-eclampsia, and neural tube defects.
Obese girls gave birth to overweight babies, who started life "on the back foot" and were predisposed to obesity, Mr Fry said.
"We've got a substantial number of our children going into their secondary school life ill-equipped to know what the consequences of fatness and obesity are."
"If we're going to see the end of this problem we need to be addressing it from the word go to ensure we do all we can to stop children becoming fat in the first place."
"We need a thorough reappraisal of the way we allow the food industry to get away with stuffing unhealthy levels of fat and sugar into their food."
"We need to ban fizzy drinks and sugar-laden drinks entirely. We need to take really radical steps.".