Ok so let me tell the early history of this shyt since I grew up in the 80's and early 90's. Back then it was cool to be fit. If you watch those videos from the 80s and 90s those women had tight bodies with maybe just a little hump of nubian booty. It was taboo to have too much azz or titties and it was seen as ghetto/low class. Also people generally worked less in the 80's you still had a 40 hour workweek, so most moms had enough time to still prepare a meal. Growing up in the 80s McDonalds was like an occasional treat, not an everyday thing. Also the 80's was kind of a fitness boom, you had the rise of home fitness systems, a lot the major gym chains came up in the 80's and you also had the popularity of drugs that hyped, you up and kept you from eating (ie Cocaine). Remember those styles were basically tight jeans, spandex, bike shorts, tanks etc. If you were a big woman coming up in those days you had 2 options in terms of dress wear loud crazy looking clothing or dress like a dude that was it.
Now let's fast forward a few years. In the early 90's it was still cool to be fit but there had started to have a backlash. Feminist started to say that fashion was having an unhealthy effect on the average female image. A lot of women women were starving and purging themselves to look like models and it started to get national attention. Oprah also rose in popularity due to the fact that she represented 'everyday' women and not just black either. Obviously Oprah was battling weight issues, that coupled with the fact that she was so viciously made fun of made her a sympathetic figure. Tyra Banks in a lot of ways represented the change, Tyra was considered 'curvy' but if you saw those pictures today you would say she was skinny but really, she was thick by model standards, models in general rounded out a few pounds and the 12-year old boy aesthetic was getting less popular. Also too by the mid 90's you had the continuing rise of commercial hip-hop which brought about models that were wider in the hips and azz and had bigger breasts. Actually this was the time period where 'thick' became a real word. There was a skyrocketing rise in the the viability of plus size female fashion and the curvaceous figure, by the late 90's more so with the rise of Southern hip-hop and the increased use of curvier models. It wasn't cool to be fat but it wasn't the end of the world either.
Let's fast forward another decade or so, 'thick' has expanded in definition and basically encompasses most overweight women, I saw a woman who weighed 200 pounds and considered herself skinny. Women like Beyonce have popularized the turn bootylicious and have made it an all-encompassing term. Furthermore online dating has made large women feel more empowered than they ever have been in any point in history, they not only get to considered as objects of desire but they can have just as high standards as their thinner counter parts. I mean you have sex symbols like Drake (nh) shouting them out in songs, you have blogs congratulating them on not changing, and large woman have successfully taken fat shaming out of the American lexicon for the most part. In today's society there is no penalty for being an overweight woman, aside from health. She can find clothes more easily than ever, she can find a man more easily than ever (should she want that), she has more access to food and entertainment than ever, and an entire subculture dedicated to her worship.
In fact this mentality is spreading as more countries have more access to food, water and entertainment this will become the norm though not at the same level as it is here.