What: Shares of weight management services specialist Weight Watchers International (NYSE:WTW) surged as high as 20% on Tuesday after positive comments from a Wall Street analyst.

So what: Weight Watchers shares have fizzled during the past couple of weeks after their 20% Oprah-fueled pop last month, but a bullish report from ITG Investment Research today suggests that the company's partnership with the media queen is paying off where it counts most: subscriber growth. Of course, the shares have quickly slimmed down from its Tuesday highs, and are now only up about 3% at the time of this writing, giving investors plenty of frustration over yet another short-lived Oprah-centered surge. 

Now what: ITG now expects Weight Watchers to post about $260 million in sales in Q4, above the average analyst estimate of $257 million, on new membership growth of roughly 35%. "The improved trends can perhaps be partially attributed to the ownership deal with Oprah that was finalized in October," said Tomlinson. Given the company's still-heavy debt load and volatile shares, however, I'd wait for more concrete proof of Oprah's influence before jumping in.