Diana Spencer. Most fans of the show likely know her as Diana, Princess of Wales, a cultural icon and humanitarian, but when we first meet the future royal in the series, she’s 16 and dressed as a "mad tree" for a school production of A Midsummer Night's Dream. In real life, just five weeks after Diana's 20th birthday (and reportedly only 13 dates with her fiancé), Lady Spencer married 32-year-old Prince Charles—the heir to the British throne—in a global wedding spectacular.

But beyond the grandeur of the event and the elegance of the dress, there was a very private crisis happening in the young royal's life. As The Crown documents, Diana was living with bulimia nervosa, an eating disorder that, she revealed in recordings featured in the documentary Diana in Her Own Words, started after her engagement to the Prince of Wales.

“I’d shrunk into nothing," she says in the documentary. Her waist whittled down from 29 inches the first day she was measured for her wedding dress to 23-and-a-half inches on the day of her wedding. The night before her wedding, she was "sick as a parrot" after a “very bad fit of bulimia.”

“I felt I was a lamb to the slaughter, and I knew it," she says.

The public first learned of Diana's eating disorder in 1992, when biographer Andrew Morton published Diana: Her True Story. Diana herself had been the source for details about her illness. “The bulimia started the week after we got engaged,” the princess recorded herself saying. "My husband put his hand on my waistline and said: 'Oh, a bit chubby here, aren't we?' and that triggered off something in me. I remember the first time I made myself sick, I was so thrilled. I thought, ‘this is the release, the tension.’”

In 1995, Diana spoke directly about her bulimia in an interview with BBC journalist Martin Bashir. “I had bulimia for a number of years,” she said. “And that's like a secret disease. You inflict it upon yourself because your self-esteem is at a low ebb, and you don't think you're worthy or valuable. You fill your stomach up four or five times a day—some do it more—and it gives you a feeling of comfort. It's like having a pair of arms around you, but it's temporarily, temporary. Then you're disgusted at the bloatedness of your stomach, and then you bring it all up again."

This kind of openness, from someone whose every move was followed by the press, had a major impact on the stigma surrounding eating disorders.

Lauren Smolar, the Senior Director of Programs at the National Eating Disorders Association, tells ELLE.com that what followed is what people in the eating disorder community call "the Diana Effect": "By sharing her story, Princess Diana encouraged people who recognized their own symptoms in her experience to seek diagnosis and treatment," Smolar says.

Diana was a champion for those struggling with eating disorders. In a keynote address in 1993, she shared that she had met with young people living with the illness:

On a recent visit to The Great Ormond Street Hospital for Sick Children, I met some young people who were suffering from eating disorders. With the help of some very dedicated staff, they and their parents were bravely learning to face together the deeper problems, which had been expressed through their disease. With time and patience and a considerable amount of specialist support, many of these young people will get well. They and their families will learn to become whole again. Sadly, for others, it will all be too late. Yes, people are dying through eating disorders.

Smolar says Diana might've been one of the first public figures to speak about her eating disorder, and her courage and influence helped other celebrities do the same. "When high-profile figures speak up about their own struggles, it really helps people who are suffering feel less alone," Smolar says. "When people with EDs see their experience is one that other people also deal with, and that there are treatment options available, they are more likely to seek help." Smolar points to TikTok influencer Charli D'Amelio, who revealed her eating disorder and shared a link to NEDA's helpline in September. "The helpline was noticeably busier than usual and we had a 300 percent increase in website traffic," Smolar says.

And just as Diana did not shy away from telling her story, neither did the popular (albeit fictionalized) Netflix show.

"I was very determined that I didn’t want it just to be alluded to—I didn't want it just to be a flushing of the toilet or her wiping her mouth," Emma Corrin, who portrays Diana, told Vogue. "I wanted you to see her experiencing it because she was so candid about her struggles with the media, which I think was incredibly ahead of her time."