It is not just poor people or “Western” countries suffering from this, UN/WHO have noticed it globally especially where there are cities.
It also increasingly affects pet cats and dogs.
Also I don’t remember “low fat/low sugar” food until well into the 1980s and kids who grew up in 1970s/80s as I did ate just as much if not more junk food. In the UK it was still permitted to advertise it on TV to the point commercial kids TV was funded by the junk food manufacturers (and probably still is in USA)
TBH I don’t think its the kids or parents fault as such, there are way too many motor cars in most city areas (other than DK, NL and bits of DE) as well as dangerous road designs and “unfriendly” urban planning which leads to road-rage and interpersonal violence (and that still affects the “nicer” European countries).
So parents end up driving their kids to and from school or other activities and only allowing them to travel unsupervised at later ages in life.
At school they have often sold off playing fields and “unwanted” buildings to commercial buyers, reducing the overall size of a school campus (unless its a posh private school which not everyone can afford and isn’t usually found in an urban area). The school day has been changed in many districts, reducing the length of break (recess) and lunch times. CCTV, electronic monitoring, and kids actually being better behaved these days makes going “out of bounds” and wandering the local area much more difficult. There are also way more tests and exams even for junior school kids.
It is hardly surprising that the kids when they get home and have done their homework often only want to play computer games or watch online TV and sit down with some junk food whilst their parents and the dog (which has given up on being walked today) are watching rubbish on normal TV and sharing similar food; the cat (who is often kept indoors or doesn’t venture as far as they used to) is blagging food from both generations. Thus everyone ends up putting on weight..
