> People in the 50s weren't slimmer because they had ironclad determination to stay such.
No. They lived in an overall healthier environment. But they were also subject to much greater social pressure to stay slim and could endure fairly intense social judgment and stigmatization for weights that we consider normal (particularly women).
"Overall healthier environment". Meaning, food was relatively scarce. No Starbucks, Dunkin Donuts, convenience store on every corner. Coca-cola was not available in 2-liter bottles or in 24 packs of cans. No Costco-sized mutlipacks of anything.
In the 1950s, malnutrition was a serious issue that many people in poor areas died from. When was the last time someone died because they didn't have access to food? Obviously, the other side of that coin is that food being so plentiful, people eat much, much more than ever before.
Then why are people scrambling for Ozempic? If it were true that "people think being fat is totally fine or desirable now" then this wouldn't be a blockbuster drug.
Weak thesis.
They smoked.
> They lived in an overall healthier environment.
They lived in a different environment. The universal appetite-reduction drug was nicotine, and the common methods of administration had a number of undesirable side effects.