The U.S. Federal Trade Commission on Jan. 4th announced fines and penalties of $25 million against the makers of four popular diet pills for false advertising claims, but the pills -- Xenadrine EFX, CortiSlim, One-A-Day WeightSmart and TrimSpa -- will remain on store shelves.

The fines were imposed as part of a settlement with the makers of the popular pills, which have combined sales totaling hundreds of millions of dollars.

Some of the fines could be returned to consumers who purchased Xenadrine EFX and CortiSlim, but purchasers of the other two pills, whose marketers paid civil penalties, will not see any refunds.

Consumers who purchased Xenadrine EFX and CortiSlim directly from the marketers will be contacted by the FTC about getting their money back, while people who bought the pills in stores should watch for a public notice on the FTC Web site telling them how to recoup money.

In announcing the settlement, FTC officials did not pass judgment on the effectiveness of the products.

But they did say that company marketing claims -- typically including a promise of weight loss even in the absence of dieting and exercise -- were not supported by sound research and fell afoul of the truth-in-advertising laws that the FTC oversees.

The largest fine was levied against the marketer of Xenadrine EFX, a New Jersey company that will pay at least $8 million and as much as $12.8 million. FTC Chairman Deborah Platt Majoras said Xenadrine had a study showing that people who took a placebo lost more weight than those taking the pill.

The FTC's investigation also found that people who appeared in the before-and-after pictures in many Xenadrine EFX ads actually lost weight by engaging in rigorous diet and exercise programs.

A $12 million fine was assessed against the California marketers of CortiSlim. Majoras said that beyond promising that all users would see permanent and fast weight loss, CortiSlim's TV infomercials were "deceptively formatted" to appear as talk shows rather than ads.

The Bayer Corp. will pay a $3.2 million civil penalty to settle FTC charges that it marketed One-A-Day WeightSmart with unsubstantiated claims including that it increases metabolism.

The New Jersey marketers of TrimSpa will pay $1.5 million for having inadequate scientific evidence to support claims that TrimSpa causes rapid and substantial weight loss.

Some of the products marketed their claims through celebrity endorsements. Anna Nicole Smith, for example, has endorsed TrimSpa.

"Testimonials from individuals are not a substitute for science," Majoras said. "And that's what Americans need to understand. If you want to lose weight, focus on diet and exercise. Paying for fad science is a good way to lose nothing but cash."