"Fat Monica" is an intrinsic part of Friends’ canon that it cannot seem to escape, even 25 years later
https://ew.com/tv/2019/09/04/fat-monica-friends-25-years-later/
"Even if you overlook the fatphobia that follows this character around like a shadow, you’ll find that the biggest problem with Fat Monica is how the show used her to garner cheap laughs in the laziest ways possible," says Clarkisha Kent. "Everything from how the character was designed — à la the svelte Courtney Cox in a fat suit rather than an actual person who was, gasp, fat — to how the character acted was greatly exaggerated to elicit laughs — and not much else." Kent adds: "Could the show have treated her better? Sure. But that would have deprived it of 'reliable' laughs at the expense of a fictional fat character doing normal things like eating, dancing, or simply living. Fat Monica worked in a horrendously offensive sense in that — in an era where SlimFast was popping, extremely thin models like Kate Moss were It girls, and 'heroin chic' was the prevailing fashion trend — pop culture fed a hysteria over being or becoming fat. And Fat Monica allowed people to take those anxieties about fatness, project them onto the character, and laugh at them. And be comfortable in laughing because whatever happened, they would never be as fat, sloppy, and socially inept as 'Fat Monica.'"