In 1988, Oprah Winfrey tugged a red wagon filled with fat across the stage of her television show to represent the 67 pounds she said she had lost on a liquid diet. Just a few years later she renounced dieting, but her fluctuating weight and the bias she has experienced because of it have remained frequent topics of discussion for both Ms. Winfrey and the media in the decades since.

Now, Ms. Winfrey, 69, has once again joined the discourse around diet, revealing on Wednesday that she had started taking a medication to manage her weight. Her announcement comes as demand has soared for new drugs like Ozempic, Wegovy and Zepbound that can help people lose weight, in part by suppressing appetite.

“The fact that there’s a medically approved prescription for managing weight and staying healthier, in my lifetime, feels like relief, like redemption, like a gift, and not something to hide behind and once again be ridiculed for,” she told People Magazine. Ms. Winfrey said she had decided to start taking a weight loss medicine after hosting a panel discussion, which she said had disabused her of the myth that weight hinges solely on a person’s self-control.

“I realized I’d been blaming myself all these years for being overweight, and I have a predisposition that no amount of willpower is going to control,” said Ms. Winfrey, who did not name the drug she was taking. A representative for Ms. Winfrey did not respond to a request for comment.

In the past year, Ozempic and drugs like it have upended conventional wisdom around willpower, weight and stigma. Perhaps no one more prominently embodies the cultural conversation around those issues than Ms. Winfrey.

“We can see Oprah as a crystallization of a broader struggle that many of us have with our bodies, going up and down in weight, when in reality our bodies are just comfortable at a higher weight than is deemed socially acceptable,” said Kate Manne, an associate professor of philosophy at Cornell University and author of an upcoming book on anti-fat bias.