As the previous posters said, we were a lot more active in the 1970s (and 1980s and 1990s.) As children we were out probably 8 to 10 hours a day in the school holidays running about, playing games and sports, and cycling. And even at school we did a lot of PE - and running about in the playground, and a lot cross-country, rounders, netball, and badminton etc. And I am not even sporty! These things were mandatory then. I NEVER see/hear of all the children doing this on a regular basis now.
We even had a few hours of playing outside on a school day (after school) some of the year, and I used to go swimming with my dad a lot. AND I used to spend half my waking hours on my bicycle.
In addition to this, when I was a young adult in the late 1980s and 1990s I used to cycle 3 miles to work every day, (and back,) and when I worked a mile and a half away I used to walk to work (and back) every day. I think very few people do this now. People drive or take the bus or train. Many people don't even work close enough to walk or cycle. Also, every young mum I know in my village drives everywhere. I don't see them going for walks. Same with most people.
But I do notice that even when you watch old episodes of FRIENDS from 30 years ago - 1994. the girls (Monica in particular) are whippet-thin. And yet at the time - when we watched it , they just looked - well - normal if you like.
Also, the 'fat' bloke out of the Full Monty (Mark Addy) was the chubster of the group (late 1990s,) and now when you see The Full Monty, he just looks like he's got a dad-bod. He doesn't even look 'fat.' Many people were so thin then that anyone even just 2 stone overweight was classed as a fat person, and called names.
My daughters are 5 foot 5 and 5 foot 7, and quite slim and athletic. They're a size 8 to 10, with a 27 to 28 inch waist, and wider hips than girls had 30 years ago, and they have fuller breasts... They're classed as slim/athletic girls..
I had 22-23 inch waist when I was their age. (I'm 5 ft 4,) and a 28 inch waist would have been cast as chubby then. It's so odd. We've changed and we've evolved - but certainly yes, 30 to 40 years ago, people were smaller and women had thinner waists and thinner arms/smaller bums/smaller breasts. I don't think people eat any worse though. Some people eat a bit unhealthily now, but then they did in the 1970s/1980s/1990s too.
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