“I know I am not completely innocent when it comes to his weight. I have always struggled myself and have some bad eating habits, but I tried hard to change the way we both ate.”

The turning point came on a holiday last year to the US. Her son was too big to go on certain rides at a theme park. Upset and humiliated, he went on a six-week weight-loss camp and lost nearly three stone (18kg). The camp was run by Wellspring UK, one of a number of firms offering camps in the UK.

“He had always refused to go before but now he wanted to. He is a different child now, so happy and confident. Before he had no self esteem and would have temper tantrums. His whole attitude to food has also changed, he now picks the right stuff to eat.”

Some parents know they are a bigger part of the problem. Tracey says she allowed her daughter to pick up her own bad eating habits. Admitting to having a “complicated relationship” with food herself, she says she used it to bond with her daughter.

“We would snack together in the evening while watching television and treat ourselves with sweets and puddings. It was like our special time together,” says the mother-of-one from Shrewsbury.

“I could see she was carrying a few extra pounds but she seemed happy. I didn’t want to mention it because I didn’t want her to feel negative about herself.

“When she started secondary she was almost 14 stone (89kg) and by then her bad habits were hard to break. I know I am responsible and I feel awful about it.”

Despite the rise in child obesity, experts say it’s wrong to just blame parents.

“They definitely have a responsibility, but the issue is much broader than simply blaming them,” says Paul Gately, professor of exercise and obesity at Leeds Metropolitan University. He also runs weight loss camps for overweight children.

Many parents don’t realise their child is fat when it might be obvious to other people, he says. According to studies, 75% of parents underestimated the size of an overweight child, while 50% underestimated the size of an obese child.

Even more surprisingly, a similar study of healthcare professions produced nearly the same results. It was carried out by Gately and his colleagues.