The term “USBBW” (Ultra Sized Big Beautiful Woman) was adopted in the U.S., circa 2010, and refers to women Size 32 up to 600 lbs.
It is in between the weight classes of "SSBBW" (Super Sized Big Beautiful Woman), which is 350 lbs and up. And the current highest weight class (as of 2021) of "USSBBW" (Ultra Super Sized Big Beautiful Woman), which is 600 lbs (272 kg) and up.