I agree 100% with Bunty. I was a slightly overweight child, and talking to me led to secretive eating. Weight has always been a struggle for me, but I had to come to terms with it on my own.
One of my children also was overweight. I never said a thing to him. I increased his activity rather than cut his food. My children did get unhealthy snacks, but not daily, we didn’t eat dessert, and their diets were healthy.
As a teen, my son slimmed down in his own.
I don’t think every overweight child will slim down on their own, but focusing on their weight will more likely than not have negative effects-secret eating, self loathing and self esteem issues.
I suggest a healthy breakfast such as eggs and fruit. You can’t control his other meals, so ensure he gets a lot of exercise. Perhaps you can go for a long walk together before bedtime.
I focused on activity, and I think that helped my son as a teen.
There are studies that suggest overweight children are “clumsier” and slower, physically, than normal weight children. I think that’s a chicken/egg situation. As a teen, my son became involved in American style football. The training, particularly the footwork, made him very agile. So consider that as well.
Finally, if he eats before bed, stop that over time.