Oprah Winfrey announced she was leaving WeightWatchers on Thursday and giving away all her stock – a move that follows the TV talk queen revealing that her recent dramatic weight loss was due to taking new weight-loss drugs.

A statement from Winfrey issued by the company said that the talkshow host, a public face for WeightWatchers since 2015, would donate all her shares in the company to the National Museum of African American History and Culture “to eliminate any perceived conflict of interest around her taking weight-loss medications”.

According to the company’s financial statements, Winfrey’s stake in the company was valued at more than $18m. The company said that Winfrey, 70, will still continue to work with WeightWatchers as an advocate for weight health and obesity issues by “elevating the conversation around recognizing obesity as a chronic condition, working to reduce stigma, and advocating for health equity”.

An apparent conflict between WeightWatchers, which promotes a non-medical, points-based approach to food intake, and the talkshow host came in December when she told People magazine that she integrated GLP-1 drugs, brands that include Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound, into her existing “holistic approach” of “regular exercise and other lifestyle tweaks”.

Winfrey said she was “absolutely done with the shaming from other people, and myself”, adding that she had “released my own shame” about using a prescription weight-loss drug.

She said her weight fluctuations had “occupied five decades of space in my brain, yo-yoing and feeling like, why can’t I just conquer this thing, believing willpower was my failing”. “It was public sport to make fun of me for 25 years,” Winfrey added. “I have been blamed and shamed, and I blamed and shamed myself.”

The US Food and Drug Administration (FDA) has said that weight loss drugs, which disrupt the stomach’s hunger signals to the brain, should be prescribed only in combination with, not as a replacement for, diet and exercise programs.

WeightWatchers, founded in Queens, New York, in 1963 has already made moves into the clinical space of the $142bn weight-management industry.

Last March it announced the acquisition of Sequence, a company that, it says, “pairs clinically-proven medications with access to board-certified clinicians, registered dietitians, fitness coaches, and a care coordinator” to achieve customers’ weight loss.

According to the FDA, 39% of Americans are obese, and another 31% overweight and 8% are severely obese. “In general, rates of obesity are higher for Black and Hispanic women, for Hispanic men, in the South and Midwest, in nonmetropolitan counties, and tend to increase with age,” the administration says.

According to JP Morgan, the market for GLP-1 drugs, which can cost $1,000 a month, will exceed $100bn by 2030. Total GLP-1 users in the US may number 30 million by 2030 – or about 9% of the overall population.

“The increasing appetite for obesity drugs will have myriad implications, boosting sectors such as biotech and creating headwinds for industries such as food and beverage,” the bank’s report said.