Being fat seems to be interpreted—at least in some society—as a sign of inferior personal virtue: being lazy, greedy, lacking self control. It is also read, perhaps more accurately, as a sign of unfortunate genetics.
In the age of GLP-1 drugs and the like, being fat shifts to partially a sign of not taking GLP-1 drugs, which makes it increasingly a sign of different traits, such as lack of spare wealth and reluctance to chemically modify your body (albeit a very imperfect sign).
I wonder if such body modifications will reach a level of cheapness, availability and acceptance that it is hard to read much of interest into being fat at all, much as it is now hard to read much into someone having a purple sweater or not. And then people can be fat in peace.

Tyrian purple is made from sea-snail mucus! Gross! But also fascinating.
One thing I interpret from fatness is that is a reflection of culture. I'm living in Rome for six weeks right now, and it's kind of startling to see a truly obese person. Young Italians are apparently extremely body-conscious, and I'll bet 95% of them are slender. Some older out-of-the-game Italians might carry a bit of extra weight, but not a lot. When you see a fat person here, it's a tourist.
I'm guessing it's self-consciousness, diet, and exercise at work. People eat better food, and fewer calories over here. They also walk everywhere, because it's expensive and a huge hassle to drive or park a car in this city.
The interpretation is pretty accurate in my case: I’m fat, lazy, greedy, lacking self-control, poor, ignorant about GLP-1 or any other such drug and uninterested in them. My genetics don’t seem to be very unfortunate looking at some other members of my family; I am entirely to blame.
Why should we be fat in peace? I don’t want to—it’s not okay to be fat.