This is just a smokescreen, the real problem is junk food sweets, crisps, fizzy drinks etc , TV and games consoles.
all consumed, played and watched from the comforts of their own nice cosy warm bedrooms.
Until you get kids off of these you wont stand a chance in hell to get them playing sport out in the open , especially in winter let alone summer.
Its like asking a middle age couch potato to lose weight and keep it off, it require a change of lifestyle and for the vast majority it doesnt happen.