May 11, 2012 -- quicklist: 1title: text: When legendary beauty Elizabeth Taylor packed on the pounds, she found herself the butt of late-night jokes...but today, she might find herself making millions off endorsements.
As the success of celebrities like Valerie Bertinelli and Kirstie Alley shows, waging a public battle with the bulge is no longer a detour from stardom.
Celebrities "are able to monetize just getting fat and losing weight," explained Jo Piazza, author of the 2011 book "Celebrity Inc.: How Famous People Make Money."
The key, Piazza said, is teaming up with a weight-loss company. Bertinelli became the face of Jenny Craig and lost 50 pounds in the process.
"I believe in Jenny Craig. They've gotten me to where I am today," the former "One Day at a Time" star said in a 2009 interview with ABC News.
After shedding the weight, Bertinelli went on to become a best-selling author with the book "Losing It: And Gaining My Life Back One Pound at a Time" and scored a starring role in the cable sitcom "Hot in Cleveland."
Piazza said celebrities take home anywhere between $500,000 and $2 million for endorsing diet programs. New mom Jessica Simpson reportedly signed a Weight Watchers deal worth $3 million.
"Jessica has not been shy about gaining weight with this pregnancy," Piazza said. "But I think that she hasn't been shy about it because she knows that she's going to do a diet endorsement deal when all of this is over."
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quicklist: 2title:text: Piazza estimated that Valerie Bertinelli's earning equaled roughly $60,000 for each pound she lost. On average, she said, celebrity diet endorsers earn about $33,000 for every dropped pound.
But they don't do it alone. Piazza said that, unlike your average dieter, celebs often have the benefit of personal chefs and personal trainers.
Stars like Bertinelli have kept the weight off...but putting it back on doesn't mean disaster for celebs either. Case in point: Famous yo-yo dieter Kirstie Alley.
Alley signed on to work with Jenny Craig in 2005. She went on to lose 75 pounds, according to a Jenny Craig spokesman, but then gained it all back and then some.
Today, Alley is svelte once more after competing on ABC's physically grueling dance competition, "Dancing With the Stars" last year and starting her own grassroots fitness campaign, "100 Days of Dance."
What's more, Alley started her own weight-loss program, called Organic Liason, consisting of weight-oss products, dietary supplements and online tools such as a menu planner.
"Now, instead of just being paid by Jenny Craig, she's making all the profits," Piazza said.
Piazza suggested Alley regained the weight she lost with Jenny Craig on purpose.
Said Alley, "I wish I was that smart, I'd be a billionaire by now."
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quicklist: 3title:text: While female celebs fronting weight-loss products have included singers like Jennifer Hudson (for Weight Watchers) and actresses like Bertinelli and Alley, former athletes seem to be preferred weight loss role models for men.
Piazza calls retired quarterback Dan Marino, a spokesman for Nutrisystem, a "breakout star."
"Athletes are aspirational to men. Every man secretly thinks that he's Dan Marino in his prime -- he just has to lose about ten pounds to get there," Piazza said.
In contrast, ads by "Seinfeld" star Jason Alexander for Jenny Craig just didn't have the same impact, Piazza said.
"Jason Alexander's ads were hilarious, but frankly, men don't want to lose weight to look like George Costanza," Piazza said, referring to Alexander's "Seinfeld" character.
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quicklist: 4title:text: Charles Barkley is one of the latest former athletes to jump on the weight-loss bandwagon. The retired basketball player-turned-sports commentator said he's lost 42 pounds while being a spokesman for Weight Watchers.
"I can't believe I'm getting' paid to lose weight!" he told "20/20" correspondent Deborah Roberts. "This is the greatest country in the world!"
Watch the full story on the latest episode of "20/20" online.media:16322827caption: use