Every year I go to Ren Faire, hang out with people who are wearing the same garb they made 25 years ago or more as spring chickens, wear my home-made garb that's maybe 4 years old and a different gender ago, and become a little more radicalized against the fashion industry.
I see old pictures of my faire aunties and uncles from back when it started in the mid-1990s and they might be wearing the exact same shirt this year 150 lbs. heavier with age moving everything around. The faire owner when she was 8 months pregnant was still in her usual garb with the bottom laces loosened.
I wore about a size 32 pant and a woman's large shirt when I made my Venetian robe, and now I wear a size 42 pant with an XL men's shirt and medical transition totally changed my fat distribution. Still fits fine. I really should get around to improving the sleeves, though. I have a shirt I bought around 17 that has ample room for me two decades older. Heck, I wore the skirt I bought with it during setup because I didn't pack shorts and I was so hot it was skirt, underpants, or sweltering to death. (Did get me misgendered by the tall lad who hung our tent light, but he was cool about a correction, so well worth it.)
Meanwhile I'm quietly anxiety spiraling that I won't fit into the nice outfit I put together (mainly through thrifting) for my friend's wedding because post-industrial mass-market clothes (even nice ones that last) are intentionally hostile to human bodies in order to both artificially drive new sales as people grow out of clothes and because fatphobia views weight-gain as a punishable offense that must be systematically discouraged. These clothes want to make me feel bad to sell me something.
A lost spring chicken of a faire participant wandered into our yard last year and we adopted her. She had a great time so she came back this year in a fast-fashion costume dress that was cute, and we helped her wear it well (because you never dis someone's garb and you never offer advice for improvement without permission, but also girl let me introduce you and your boy to ladder lacing because it will make both your bust and boots so much more comfortable and elegant), but it was not structured or supported, and offered her no liberation from a bra.
I was in and out of all our bins on Sunday after our tent flooded and we had to dry everything. So I kept seeing the blue linen side-laced kirtle dress I'd made, some of it hand-stitched at the faire. I made proper lacings eyelets by using an awl to stretch the fiber weave away from the hole without breaking, and stitching around the edge to hold them back. Much, much stronger, but also a pain in the ass and I was still sewing it the night before I had to wear it.
Our new lass was about my hight and I noticed she had a high waist that her dress was fighting. It's a sentimental piece of clothing to me, but I kept asking myself if it's highest use was sitting in my costume trunk or finding a new person to love, cherish, and use it. I think I wore a medium in women's sizes when I made it. The lass was sure it would be too small, and indeed it didn't fit with the existing laces (the spiral style that are tied in at both ends). But I told her before giving up we should undo the bottom of the lace and just let it pull out to where it wanted to be, and then see how she felt. And sure enough the exposed shirt was a little wider than you'd intentionally make it, but it fit her so well and she looked so much more pretty when her clothes weren't fighting her to be their size (hight and girth and curve locations) and instead changed to accommodate her real body just as it was. That thing was more comfortable and safe than any bra I ever wore (with literally 10lbs. of tit's being corralled) and back in those days I was raising shade tents with supports the size of telephone poles being raised into place with humans holding ropes, put up big heavy canvas pavilion tents (sometimes in the wind and rain) in that dress because it was so much more comfortable than my mundane clothes. Next year I will bring more of the blue cording I used for the ties and we'll get properly fit. Might even still have the blue linen in my stash to make expanded side panels.
Your body isn't wrong. Your clothes are intentionally being made to make you feel wrong so you either buy more clothes to accommodate weight fluctuations, or succumb to the diet industry selling you snakeoil. We don't have to keep having this horrible relationship with our clothes. We can look back to far more sustainable, comforting, elegant, and humane ways of making clothes that last and change with your body. That are fit to your body in the first place. There are solutions all over the world, but the imperial juggernaut Western clothing manufacturers keep pressuring people to abandon them and treat them as not "fashionable". Fuck that.
Clothes should be made for your human body. Your body should not be shamed for not fitting industrial sizes or for changing thinner or fatter over time. This too is both body positivity and fat liberation.