Ideas about dieting shift. People pick up the ideas and don't always let them go when they're debunked. Like a lot of dieters, Mom had her collection of ideas.
Which brings us to salt. One of the ideas that Mom collected was the idea that she was retaining water. Salt makes women retain water.* Therefor, Mom never used salt. She used granulated garlic instead.
If she had been born later, there would have been more salt substitutes available. But if they were more expensive than 'garlic powder',* she wouldn't have used them. If she had been born much later, she wouldn't have been put on thyroid pills.
Under-active thyroid was what women in the late fifties and early sixties were diagnosed with if they had trouble losing weight after they had a couple of kids. The trouble is that if you give someone thyroid hormones, and they're not making less hormone because if an insufficiency, the thyroid feedback circuit tells the thyroid gland to produce less, so that you have to keep raising the dose to maintain the same low level in the blood. Unless you're taking enough to shut your thyroid gland to shut down completely, the level will not rise.
Decades later, a new doctor slowly weened Mom off of the thyroid pills. There was no change in her weight from it.
Another thing that she did for while, but gave up on, was making her own salad dressing. Oils and fats were evil. So she'd shake up her own salad dressing with vinegar and garlic. No salt. That only lasted a few years.
I don't know if diet or oil-free dressings were available for purchase back then. It wouldn't have mattered. We didn't buy salad dressing on principle. It was cheaper to make your own, if you really needed it. And mayonnaise was perfectly good for most of the time.
Once in awhile we'd make our own thousand island dressing. We'd add catsup and pickle relish to mayonnaise. By the time I was in junior high, there were mix your own packets available, which we tried. They never became a regular feature.
Mom used pickle relish on other things, to add flavor. No one ever mentioned that it had salt in it.
Because oil and fat were evil, Mom used a teflon pan to cook beef liver in. It wasn't until I was in college that I learned that liver didn't need to be a grey, dry hunk of shoe leather. Oh, and to be sure it didn't stick, she'd sneak a little bit of water into the frying pan after it was partly cooked, and then put a lid on it.
Other people bread liver and fry it in actual grease, and if it's done properly, can be tasty. Actually frying it makes a world of difference.
I'm pretty sure that she was overcooking it, too. It wasn't a dieting idea, just a regular how to eat food idea. Both of my parents were squicked out at the idea of blood in meat. Well, maybe it wasn't because of the blood. But all meat had to be well done.
So, salt, thyroid, and oil. That's the big three. I don't know that she ever left avoiding salt and oil behind. She did pick up other ideas along the way. But by then, I wasn't having to eat along with her, so I paid less attention.