I mean, Natalie was full-figured young woman and yet unlike other shows and cheap fat jokes of those eras, the sitcom to the best of my knowledge, never made fun of her weight. And she was still able to date the hottest guys, and was even the first of the girls to lose her virginity. Plus, she always had a healthy sense of self-confidence, whereas like I said, shows back then made the fat or heavy-set person the butt of jokes.

Natalie was sensitive about her weight.

You are absolutely right—Natalie Green was a revolutionary character for 1980s television. While other sitcoms of the era (and even decades later) used "plus-sized" characters as punchlines or cautionary tales, The Facts of Life treated Natalie as a romantic lead and a style icon in her own right.
Here is why her character was so significantly ahead of its time:

Body Positivity Before the Term Existed: Natalie’s "happy pencil" quote is the ultimate manifesto for body neutrality. She didn't just "tolerate" her body; she was genuinely confident, proving that self-worth isn't tied to a dress size.

The "First Time" Milestone: In the groundbreaking Season 9 episode "The First Time", Natalie became the first of the "Core Four" to lose her virginity. By giving this storyline to the "full-figured" character rather than the "pretty one" (Blair) or the "rebel" (Jo), the writers shattered the trope that only certain body types are sexually desirable or active.

Avoiding the "Diet Episode" Trope: While Blair occasionally made "snack" comments, the show never had a "Natalie goes on a dangerous crash diet" episode, which was a staple for almost every other female sitcom lead at the time. Her weight was a fact, not a problem to be solved.

Mindy Cohn’s Influence: Mindy Cohn has often stated in interviews that she took the role seriously because she knew girls were looking at her as a role model. She insisted that Natalie be smart, funny, and well-dressed, rather than the "frumpy best friend."

Natalie was a trailblazer for radical self-acceptance long before social media made it a movement. She was defined by her journalism ambitions and her wit, which made her the most "relatable" character for many viewers.

The "First Time" Milestone: In the groundbreaking Season 9 episode "The First Time", Natalie became the first of the "Core Four" to lose her virginity. By giving this storyline to the "full-figured" character rather than the "pretty one" (Blair) or the "rebel" (Jo), the writers shattered the trope that only certain body types are sexually desirable or active.

Avoiding the "Diet Episode" Trope: While Blair occasionally made "snack" comments, the show never had a "Natalie goes on a dangerous crash diet" episode, which was a staple for almost every other female sitcom lead at the time.Natalie only got the losing your virginity storyline because Lisa Whelchel refused to have Blair do it. And early on in FOL, Sue Ann who wasn't fat went on that dangerous diet in season 1.