Paperbackwriter, I agree with your thoughts about being brought up as a baby boomer- no cappuchino wherever you go, no prepackaged ready made sandwiches and portion sizes being smaller. I only went in cafes when on holiday, no meals out at all, just mum's home cooked meals and I walked or cycled everywhere. But ..... Despite all that . I used to be fat! No dressing it up - I was fat!
Now I have a cappuchino most days, eat out maybe once a fortnight, drive everywhere then amble around my destination and I am less than 9 stone.
So in my case that theory of the good old days doesn't always stack up. There again, maybe it's just me, I have always been an oddball!
Seriously though, I think it was the daily stodgy sweet home cooking that did it for me and exercise had v little/ no impact.
Nowadays I do minimal exercise ( joint issues) but only have puddings as an occasional treat. I think in general the diet of today is way healthier than that of the 50's.