There was a time when fat was in and thin was out. Obesity was the privilege of wealth and being thin meant being poor. In simpler societies, before slumming became a romantic pose, there was nothing attractive about not having enough to eat.
To be fat was to be part of the leisure class. Thin meant you were on the road to the poorhouse or to consumption, which meant your body was being consumed, not that you were the one doing the consuming.
Then agriculture was revolutionized and the values flipped. No one in the West was starving to death and the poorest man could still grow fat. By the time the social programs kicked in, weight no longer meant leisure.
With packaged foods widely available and jobs shifting from the factory to the desk, it was entirely possible to work hard and get fat.
On the other side of the aisle, exercise meant leisure time. The standard was set by movie stars who struggled to meet unrealistic standards because they had the time and disposable income to do it.
Fat no longer meant upper class gentry. Instead it meant lower class peasant. As with art, the widespread availability turned minimalism, and eventually the worthless and overpriced, into class signifiers. Conspicuous consumption of that which was widely available was lower class.
The overflowing table made way for micro portions and exotic but barely edible foods. Thin was in on the plate and the waistline.
In many Third World countries where feudalism never ended, the values never flipped. Instead of anorexia, teenage girls suffer from being force fed to make them more marriageable. The wealthy are fat and the feasts at the top never end.
In the West, weight stands in for class, at a time when explicit classism has become politically incorrect. When Europeans sneer at how fat Americans are, and American coastal elites sneer at the rest of the country for being fat, it’s a class putdown.