The health risks for obese children may be even greater than previously estimated, new research suggests. So why do parents let their kids get fat?

The recent start of the new school year was greeted with reports of a dramatic rise in demand for extra-large uniforms for primary school pupils.

It came as no surprise to Carol. Her two nieces were wearing size 14 skirts by the age of 11, the average size worn by a grown woman in the UK.

Her son also struggled to find a uniform big enough at secondary school as his weight crept up to nearly 20 stone (127kg) in his teens.

“You do feel judged by other people when your child gets to that size, but the harshest critic is yourself,” says the mother-of-two from Birmingham.

“I constantly asked myself ‘what am I doing wrong?’”

It’s a good question. Just over 33% of 11-year-olds are now overweight or obese and among four and five-year-olds it’s 22%, according to the most recent figures from the National Child Measurement Programme, which assesses the height and weight of primary children in England. The figures are similar in Wales, Scotland and Northern Ireland.

New research published today by the University of Oxford also suggests that obese children and adolescents have several risk factors for heart disease, including raised blood pressure and cholesterol, compared with normal weight children.

Obesity experts say parents are struggling with a multitude of problems when it comes to their child’s weight. They range from a lack of education about food, limited cooking skills and limited money to buy healthier food to longer working hours and marketing campaigns for junk food aimed at kids.

But the more sedentary lives children now lead is also creating huge problems. Last week a study suggested that up to 75% of junior school children preferred to stay at home than go to their nearby park.

Watching TV was one of the most popular activities, with 89% saying it was how they liked best to spend their time away from school, according to researchers Lightspeed. In July, scientists from University of Montreal claimed every extra hour of television that a toddler watches each week adds to their waist size by the time they turn 10.

So while the problems parents face might be increasing so is evidence about the dangers of obesity. So why do they let their children get so fat?

Katy’s son weighed over 23 stone (147kg) by the age of 15. She knew the reason - he ate too much and did too little exercise. She says she tried to help him but things only changed after he decided to help himself.

“A lot of his eating habits were out of my control,” says the mother-of-two from Buckinghamshire. “He would eat too much when he was at school and then come home and eat whatever was around, even cook big meals for himself. He wouldn’t wait for me to get home and make dinner.