On April 27, 1993, about four years prior to her death, Princess Diana delivered a powerful speech on eating disorders. The popular royal made the case for more education and empathy for those who suffered from the disease.

“Eating disorders, whether it be anorexia or bulimia, show how an individual can turn the nourishment of the body into a painful attack on themselves, and they have, at their core, a far deeper problem than mere vanity,” Diana said.

Often called “the people’s princess,” Diana’s speech was groundbreaking in shining light on a taboo subject. At the time, it was only speculated that Diana suffered from bulimia nervosa. Her battle with the illness was later discussed in depth in the book Diana: Her True Story. During a sit-down interview with the BBC in November 1995, she spoke openly about her struggle with the disease.

“I had bulimia for a number of years. 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,” Diana said in the same BBC interview.

Diana’s willingness to speak openly about the disease had a ripple effect. A study in the British Journal of Psychology showed that the number of bulimia reports in England rose in the 1990s after she admitted to suffering from the disease. Several theories were suggested, including the publication of Diana: Her True Story and the decreasing shame surrounding the illness.

Diana’s impact on eating disorder awareness was even dubbed the “Diana Effect.” The study found that the number of bulimia reports began to wane just before her tragic death in 1997.

This year marks the 20th anniversary of Diana’s tragic death, renewing interest in the Princess of Wales. TLC is airing a three-hour telecast exploring her life, legacy, and conspiracy theories surrounding her death. Princess Diana: Tragedy or Treason premieres on Monday, July 31 at 8 p.m. ET.