I've always been skeptical of celebrity endorsements. Buick once paid Tiger Woods $70 million to appear in its commercials, but does anyone believe he actually drove a Buick?

But one category where celebrity endorsements are effective is weight loss. It's a powerful thing to see the before-and-after pictures of famous people. You can really see the impact of whatever regimen they're promoting. Even if they later put the weight back on (as actress Kirstie Alley did), you know that at least they had some success.

January is prime time for weight-loss advertising, as millions of Americans make their New Year's resolutions. Nutrisystem just launched a series of ads featuring its new spokesperson, pop diva Janet Jackson. Meanwhile, singer Mariah Carey is touting rival Jenny Craig, taking over Alley's former gig.

And Weight Watchers is going after a relatively untapped category: men. Weight Watchers recently unveiled a high-profile campaign starring Charles Barkley, the uninhibited former NBA star known in his youth as the "Round Mound of Rebound."

'Lose Like a Man'
In addition to starring in TV ads and as the face of a special website, Barkley appeared earlier this month as the host of "Saturday Night Live," where he got in several plugs for his new employer and its new campaign, "Lose Like A Man."

Men are potentially a large target market for Weight Watchers, which has about 1 million members — more than 90 percent of whom are women. If Barkley can convince a few thousand men to join the program, at anywhere from $20-$40 a month, then he'll be worth the money they're paying him. That's probably in the range of $3 million, which is what Weight Watchers is paying another celebrity spokesperson, Oscar-winning actress and singer Jennifer Hudson.

But will men flock to Weight Watchers because a popular athlete tells them to? Hard to say. Weight-loss programs have always been a tough sell to men, who aren't raised to link their self-worth to their appearance, as women historically have been encouraged to do.

That may be changing, however, as today's men become more vain about their looks. The number of cosmetic surgery procedures on men increased by 45 percent over the last decade, according to the American Society of Plastic Surgeons. Men's grooming products showed a similar increase in sales.

So maybe men are ready to join what's been a historically female group. But there's one new member Barkley can't take credit for. I joined Weight Watchers last fall and have lost almost 20 pounds to date. And what got me in the door?

Jennifer Hudson! Have you seen her? She looks fabulous!