In my late secondary school days, here eight years ago, my best girl friend wore size 2 jeans, have a 25 inches small waist then an as small bust so she alterned between Small & Medium size tops. She was aged of 17 years old at this time, barely weighed up 112lbs and still stand up 5 feet 5 inches: four months ago yet then a roughly 28-51lbs more later, time same as many signifiant up-and-downs through the weight spectrum sculpted her figure such than she once admitted experiencing a lot of struggle to fit her biggest dresses (of size 12 - which means, in standard basis of 36-31-41) because of her now child-bearing hips same as her well-spoiled, soaring-up arse.
At now 25 years old, she spurts 8 and 10 size jeans (since her waist line past from 28 to 30 inches since then) , most of time M-size leggings or L-size baggy sport trousers for hide them, started back to exercice a bit more after years of slack semi-sedentarism for trim down her soft-skinny midriff as her natural ability to slim down from the belly with belittle to not effort seems to be on the wane with age, then alternate between M & L-size tops because of her slighty fuller breasts.
Though, at her heaviest (over 170lbs) last year ago, she could hardly made the littiest move into her obviouly outgrown pair of size 12 skinny jeans (though at the point she was at this very moment, even size 14 pants might been relativelly underrated) without be obligated to walk up with a ponderous, somewhat waddling sway as the fabric of her garment outstressed tightly against her flesh, their seams seeming on the verge to tear apart at any instant. Surprizingly, she still had a 30 inches waist then a belly on the way to curve out a burgeoning convave shape, only noticeable at sideway position: all the excess fat was mostly stocked in a proportional way into her chest and especially lower body frame. This is only since this present year she tend to stock a little more into her midriff area instead her bosom.
After putting some serious thought into this question. I would say the last time my waist size matched my age, was when I was 36 YO & weighed 180-185 lbs. Since then, I've gained close to 200 lbs, with most of the extra lbs going straight to my mid section, balloning my belly & the size of my waist as well. That being said, I'm happy to report that currently, I'm 55 YO, weigh close to 375, my belly is bigger, fatter than ever with a 62" waist!!!
My waist is around 46", but I'm 64 years old. Bummer, eh! I do keep older clothes too. Some of my old military uniform pants are super tight to try on, but provide quite a turn on! Sorry for the pun. I like try on and pose in old tight clothes, it make feel fatter than I am.