What: Shares of Weight Watchers International (NYSE:WTW) were up more than 20% as of 11:45 a.m. ET Wednesday after Oprah Winfrey introduced an advertisement featuring the company.

So what: Not many names can move a business like this, but keep in mind Weight Watchers stock also soared in October after it announced Oprah was joining its board and had taken a 10% equity stake in the company. Winfrey also revealed at the time she was a Weight Watchers member and stated, "I believe in the program so much I decided to invest in the company and partner in its evolution."

On Tuesday, Oprah tweeted a link to the emotional new ad to her more than 30 million Twitter followers:

Now what: The surge also comes on the heels of Weight Watchers' better-than-expected third-quarter report last month, during which Weight Watchers CEO James Chambers noted of Oprah's involvement, "The response to this partnership announcement has been terrific. The general press has taken a great interest in the news, and we have seen significant improvement in visitors to our website, which has translated into a strong response in the business, albeit during a seasonally low period."

Weight Watchers also launched a new program called Beyond the Scale earlier this month, which aims to expand its scope with a personalized approach to for each member, including new social apps and fitness tools. 

What remains to be seen, however, is whether Oprah's pronounced positive influence on Weight Watchers' results will be nearly as evident as the company shifts into its seasonally busier times of the year. For now, though Weight Watchers stock is still down around 8% so far in 2015, it has also nearly quadrupled over the last three months since Oprah revealed her involvement. As such -- and until Weight Watchers can prove this bounce is sustainable over the long term -- I'm personally content watching its progress from the sidelines.

Steve Symington has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.