Yes the typical UK kid's diet is dreadful but I still think the problem is more lack of activity than too many calories.
Lunch breaks are shorter and they don't have an afternoon break anymore so les time to play out.
The slightest rain and they get kept in.
Hardly any walk/cycle to school.
Kids aren't sent out to play all day every day of the weekends and holidays anymore.
They have more homework.
The parents dont have active lifestyles.
Ratios in swimming pools are do strict lots of kids can't go at all.
How many 8-10 year olds do you ever see going swimming without a parent?
Sport clubs etc are very expensive.
Consoles.
Kids don't walk to each other's houses to see if they are in/to play - they text them.
We need a whole cultural shift to tackle this problem, and part of it starts with ditching the extreme risk adverse parenting that has become the norm, so frequently demonstrated on mn threads.