"Food! Too much of it," says Dr Tabitha Randell, a paediatric endocrinologist at Nottingham Children's Hospital and adviser to the diabetes.co.uk forum.
"Even in the middle classes, you can have too much of a good thing. People think smoothies are healthy but they're packed full of sugar. Likewise fruit juice. Plus, children who don't eat their meals will often be given crisps or sweets later or cooked separate meals. In my house the children have always eaten the same as us and if they don't like it, they will be hungry. Saying no doesn't make you a bad parent."
READ MORE: • The world's fattest child
But what if children just won't eat that broccoli? "It takes 15 tastes to like something," she says. "It might not end up their favourite food but they will learn to eat it."And while home cooking is better than takeaways, bad habits can still form, says Deborah.
"We were cooking with lots of oil, having desserts we didn't really need and eating cereal bars and drinking fruit juices we thought were good for us.
"Scarlett would eat two chocolate croissants for breakfast and when her grandfather routinely picked her up from school, he would have Coke and a chocolate bar ready. Then came dinner of pasta with cheese and oven chips. "Beige food, mostly," says Scarlett. "And always a treat in front of the telly at night."
One study just published in the journal Scientific Reports found that larger portion sizes were directly linked to overweight children and that feeding them larger meal sizes at 21 months was associated with their gaining weight between the ages of two and five.
In fact, for every additional 10 calories children consumed at meals, their odds of being overweight grew by six per cent. This chimes with a new report by the Infant and Toddler Forum (ITF) that found one in 10 parents gives preschool children adult portions and a third see nothing wrong with them eating a whole bag of crisps, even though this is twice the recommended amount of salt.
Generation screen
While weight is a balance between calories in and out, we need to be aware of other factors, says Anna Groom, a paediatric dietitian and spokesman for the British Dietetic Association.
"Increased ownership of phones, for example, means more children are not getting the recommended 60 minutes a day of activity, with some spending up to 32 hours a week in front of digital devices. Plus, parents often tell me they're worried about the safety of their children playing outside," she says.
We need to think about our own screen habits too. "That's why we encourage whole family activities, group playing in the park, bike-riding, swimming, which can give children the freedom to play but adults peace of mind." And a break from their own devices too.
