I grew up in the area that I now live.
It is an area that suffers from Obesity.
The first difference is disposable income, there was real poverty still around in the 60/70/80's, where I live.
Food shopping meant potatoes, oats, veg and baking ingredients.
Supermarket foods were rubbish and expensive unlike now.
Fast food wasn't about until the 80's and as Marketing hadn't convinced us all that we should be eating it, it was rate that we ate out.
Cafés were a treat, but they served "real food".
Income changed and so did cooking and eating habits.
This means that families now stock up for the week at Farm foods/Iceland etc, pies, ready cooked foods and then cheap crisps, cakes etc.
The range of prepared plastic food/drink is vast compared to what once was.
Then the issue is that what goes into those foods has changed, this is born out by every piece of research. It is a fact that all of our food is different, even the veg we buy.
We change how we digest and use food, when we take in some of today's ingredients.
I can remember everyone either walking or riding bikes and carrying sacks if potatoes etc home, whilst growing up.
Housework was harder, if your electric wasn't on the fiddle, you brushed up, rather than hoovering. People still had mangles and twin tubs and still hand washed, when money was really tight.
In terms of some of the teen girls I see about, I think it is alco pops and what is in them, as well as other drinks that cause the fat storage the way it is.
Even the Cider pre 90's didn't have the calories and crap in. Everything was made differently, even the bread.
I google recipes and it can be a search to find one with a list of ingredients that don't contain prepared foods, such as Soup.
People were overweight, though and Heart Disease was killing Men.