American authorities are urging media outlets to stop running deceptive weight-loss advertising.

The Federal Trade Commission (FTC) wants the media to "do the right thing."

FTC chair Timothy Muris says the ads make claims and promises that are "clearly implausible and patently false."

Muris says the media should help to protect consumers by promoting truthful weight loss ads.

Muris says fraudulent diet ads are on the rise and cites a study of ads done by the FTC.

"Almost 40 per cent made a claim that was obviously false, another 15 per cent made at least one claim that was likely to be false or unsubstantiated," says Muris.

When the FTC compared ads from 1992 to ones in 2001, they found the recent ads were much more likely to contain false claims.

Many of these ads run in highly respected publications, which makes consumers perceive them as credible.

As a result, the FTC is creating a list of claims that can't be backed up by science but appear frequently. Muris says he hopes media companies will use the list to monitor their ads.

"Profit and prosperity are not at odds with ethical advertising."

He asked the companies to hire scientific consultants to review the commercials first before airing or printing them.

Since 1990, the FTC has brought 98 cases against marketers of fraudulent weight loss products.