The average consumer forks over between $150 to $300 a month when they sign on with a diet company that provides them with food and support in taking off unwanted flab.

On the other hand, the average celebrity weight loss endorser is paid around $33,000 a pound to dump those love handles.

To make sure stars lose those expensive inches, weight loss industry insiders say companies often also pay for personal trainers, dieticians, and whoever else they need to keep their spokesperson on the straight and extra-narrow.

“Diet companies will do whatever they can to make sure the celebrity that they hired not only looks good and loses the weight, but that the weight stays off,” explains Richard Zeeb, the former Chief Marketing Officer for the diet company Medifast, currently a marketing consultant. “It is very common to have personal trainers and nutrionists and dieticians on call whenever a celebrity wants, and whenever a celebrity needs it.”

Mariah Carey and Jessica Simpson are the latest celebrities cashing  in on gaining and losing weight while millions of Americans pay for the privilege. Carey signed on with the Jenny Craig weight loss company for an undisclosed sum, while Simpson was paid a reported $3 million by Weight Watchers before she even had her baby (due in early 2012).

FOX411: Carey Shows Off Post Baby Body.

A spokesperson for Jenny Craig said their celebrities, including Mariah Carey, receive no preferential treatment.

“Our Brand Ambassadors experience the same Jenny program as any of our other clients, including a weekly one-on-one consultation with their personal consultant, either in person or over the phone. No special treatment is provided,” a rep told Fox411.com.

Weight Watchers declined to comment.

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Jenny Craig and Carey are promoting the singer’s 30 pound weight loss since starting the program in July. But experts say weight loss figures can be blown out of proportion.

“You have to put these numbers in perspective. Mariah lost 30 pounds. That number looks huge, but she had twins,” says celebrity nutritionist Heather Bauer, author of “Bread is the Devil” and the woman responsible for Tyra Banks’ rockin’ bod. “When you have babies you drop a lot of weight fast. That number is inflated.”

Unlike some we talked to, Bauer doesn’t doubt that celebrity endorsers actually use the products they promote, but she doesn’t believe it’s all they’re using, either.

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“When you do meals in a box, you get awesome results because you are taking yourself out of your lifestyle and only eating 1,200 calories a day, so you can lose a lot of weight,” Bauer said. “Do these celebrities stick to these diets? I think celebrities who endorse these things do have two trainers a day, a chef and certain things in their lifestyle to keep the weight off.”