This thread has given me a good old blast of the past feeling.
I was a teenager in the eighties. I was considered tall at that time (5ft 7 and a half). I was not overweight. I was a size 14 which was the biggest size you could be without being a 'oversize' and nobody wanted to be that. In fact you couldn't buy size 16 in most shops, certainly not the ones aimed at teenagers. you could buy bigger sizes in M&S, BHS etc
It stuck in my mind that a size 12 which I could never fit into was around a 26 waist and my own which was a size 14 was 28 inch. I just checked the internet and it corrects me saying a size 12 was a 26.5 inch waist.
A size 14 was a 36 bust, 28 waist and 38 hips.
I think since vanity sizing came in everything is 2 sizes bigger than it was traditionally (although perhaps it has gotten even bigger now I would have to check). Traditionally there was never any size below an 8 (which is why we now have size 4's because these will be the people who used to be classed as an 8)
So I wear a size 18 now adays because I am without a doubt fat (trying to address that but definately fat). In the 'olden days' I would have been a 22.
This is what makes me realise I really, really do have a weight problem.
With everyone getting fatter our prespective of what is the right size has changed and myself included deludes myself 'oh well I can squeeze into an 18 so that is not too bad then' when in fact I am a size 22 and that conjures up imagines of women who were very fat indeed.
Humans do seem to have got taller in general since then because at 5ft 7 and a bit I no longer seem to be considered that tall. However we are all definately much fatter.