Can Oprah deliver New Year's lift for Weight Watchers?

If you haven't noticed, Weight Watchers stock has put on a few pounds in the last few months.

From a low of $3.67 a share in July, shares of Weight Watchers International hit a high of $28.05 in November, and are set to end the year at around $22 a share, a hefty gain of about 500 percent. And it has Oprah Winfrey to thank.

In October, the media mogul joined the board and took a 10 percent stake in the diet and nutrition company -- a move that promptly sent Weight Watchers shares soaring -- and agreed to appear in its advertising.

The first of those ads began appearing this week, with Winfrey asking viewers to join in her in the goal to lose weight.

"Are you ready? Let's do this together," Winfrey says in the commercial, which features footage of her through the years

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Winfrey's broad appeal and very public battle with dieting and weight loss make her an ideal choice to help revive Weight Watchers fortunes. But in an age in which there's an app for everything, will Winfrey's emotional endorsement be enough?

As Lisa Sasson, a professor of nutrition and food studies at New York University, told Crain's New York Business last year, "Weight Watchers is about dues-paying members attending support meetings at a time when consumers look to apps for personalized weight-loss advice and expect things to be free."

It helps, of course, that many of those app are indeed free or at least cost very little, compared to the $20 a month that Weight Watchers subscribers typically pay. But you get what you pay for, nutrition experts argue. Weight Watchers has a 50-year track record of helping people lose weight, and gadgets alone won't be sufficient in helping consumers to keep the pounds off.

With Winfrey on board, however, Weight Watchers is promising a new approach to enlist and keep more customers. Dubbed "Beyond the Scale," the new program promises to be a more holistic answer to losing weight and keeping it off.

"We're going beyond just getting on the scale," one trainer says in an ad touting the new regime. "Food, fitness, fulfillment -- all of it."

It'll take all that Weight Watchers can muster to keep its fortunes from flagging. Shares of the company may be enjoying a resurgence but they still remain well below the nearly $60 a share they commanded just three short years ago.

"The challenge with Weight Watchers is they've tried so many campaigns over the years, to some extent it may not be a question of advertising and more about the relevance of the product," branding expert Allen Adamson told Dow Jones Newswires.

It's a perception not lost on Weight Watchers CEO James Chambers, who recently told The Wall Street Journal, "We may be the greatest diet company on the planet but the consumer isn't thinking strictly in diet terms anymore."

As for Winfrey, she's already come out a winner as an investor. But it isn't only her portfolio that's benefiting. Since joining the Weight Watchers program, she reportedly has lost more than 20 pounds.