99% of people are just following a beauty standard, period, and most beauty standards are set based on the criteria of “it’s hard for the average person to do this.” Hence being chubby and lazy in pre-industrial times, but now that any trailer trash can be fat, thin says “I have discipline and willpower and have the time and money for a personal trainer.”
There is precedent to suggest that while it may nip at the number of super obese people, and fewer people are as fat, but in doing so, makes the quest to be super thin obsolete because there’s no status in it anymore.
When home electricity came out, the rich ate dinner in super bright light because candles became for the poors. When electricity became ubiquitous, the classy thing magically flipped it back on its head, rediscovering candlelight and dimmer switches, and calling it ambiance.