Shares of Weight Watchers International (NYSE:WTW) added $2.10, or 21 percent, Tuesday after Oprah Winfrey said in a tweet that she lost 26 pounds on the Weight Watchers diet program. "I love bread," Winfrey said in a video embedded in the tweet. "I lost 26 pounds, and I have eaten bread every single day." 

The tweet came three months after Winfrey announced buying up a $43 million 10 percent stake in the company. The news doubled the value of Weight Watchers stock and brought increased attention to the beleaguered company, which had seen its revenue slide 20 percent between 2012 and 2014.

But the honeymoon didn't last long. Weight Watchers stock has withered since a late 2015 peak of $26.56, falling more than 50 percent in December and January as the Standard & Poor's 500 fell 10 percent. 

But if Winfrey's waistline has shrunk, her pocketbook has not. Tuesday's gains meant roughly $14 million in paper gains for Winfrey, who now holds a 15 percent stake in the company and maintains a seat on the company's board of directors.

Tuesday wasn't the first time that a promotional tweet from the media mogul sent Weight Watchers stock rising. A video Winfrey tweeted to her 30 million followers in late December also boosted Weight Watchers shares 20 percent — a bounce that proved short-lived.