For starters, keep the focus off his fat. Start by mentioning that you’ve noticed the whole family needs to adopt healthier habits, says Dr Ellen Rome, head of the Center for Adolescent Medicine at Cleveland Clinic.

“Kids who feel teased or berated by their parents about their weight don’t cope with 
it well,” she says. “What you say and do matters.” So here’s your script: outline changes that you’ll all try to make together, such as eating more veggies and taking walks after dinner. Next, identify soft spots in your son’s routine. Does he eat breakfast? A study in the International Journal 
of Obesity found that kids who skipped breakfast had greater increases in BMI than morning eaters did. If he’s pressed for time in the morning, stock up on portable foods, like bananas and small packages of nuts, that he can eat on his way out the door. Another red flag: he parks in front of the TV every day. According to research from the Netherlands, children who watch 90 minutes or more of TV a day are 70% more likely to be overweight than those who view less.

Bottom line: set limits on everyone’s TV time. If you notice your son sliding from chubby into truly heavy territory, ask your paediatrician to help you devise a customised diet and exercise plan, or look for a dietician who specialises in paediatric nutrition.