I don't. I think they didn't have the opportunity to eat so much food because it was more expensive and going out was socially atypical.

When my Mom is around, my Dad gains weight, but when she's away, he loses weight. Why? She's not literally force-feeding him, but when she's around there's a fully stocked fridge of delicious treats that he would not normally seek out. He/we just don't have the willpower to fight that. Here is a delicious thing -- don't eat it. So much easier not to have it in the house -- out of sight, out of mind. Same for me with COVID. When I was initially hunkered-down and buying staples I lost weight. Once I relaxed and started going on snack-runs I started gaining weight. It's the (social) environment.

Those are personal examples of how the easy availability of food and snacks makes it more likely to overeat. As the culture changes to normalize overeating, people don't realize they're overeating and start to look for reasons why everyone is gaining weight, other than the obvious.

Regarding homeostasis -- if portion sizes are increasing, everyone is overeating, and there's a culture of trying to find every factor except overeating, then you don't just eat too much one day, you eat too much every day. A rising tide bloats all floats?

I find it really strange that we mostly ignore the advice of people who seem to be able to maintain a lower body weight (eat less, exercise more). Instead we are basically bombarded with complicated information from people who have weight problems. It's like you want to find out how to do car maintenance, but you ignore the people with well-running cars, and instead listen to all the people with terribly-maintained cars.

Being overweight doesn't mean you're a bad person, although socially and emotionally the consequences are brutal. Because of these brutal consequences, I think we're biased to find any way at all that being overweight is not due to our own direct actions. Hence the search for all of these super-complicated and subtle higher-order effects.

Could be wrong, but this is where I am after decades of watching incredibly irrational behaviour in myself, my family, and my friends. I'm convinced that it would be more helpful to treat this as food addiction, given the incredible mental contortions involved.

EDIT> As another example of social factors. I seem to remember it being socially unacceptable to have one's shirt untucked in a non-athletic context in the '80s. I remember when I first started going in to work with shirt untucked. I can hide 20 pounds under there without people considering me fat. But there was a time when if you did up your belt, tucked your shirt in, and had overhang of belly over belt you were considered fat.

On the one hand it's great that we're trying to be less brutal to heavier people. In an ideal future, people wouldn't be judged by their appearances at all. But in doing this, I wonder whether we're losing sight of the reality of the causes and effects.