Contrary to the advertising gospel of reach and frequency, a study published by the National Bureau of Economic Research found that when it comes to over-the-counter weight loss drugs, ads are a complete turnoff. And, interestingly, it found a gap in the way that men and women react to those ads.

FTC guidelines bar the use of unsupportable statements such as those that a product will generate safe weight loss of at least three pounds a week for more than four weeks, substantial weight loss for all users, or permanent weight loss. For women, the more ads making such claims they saw, the less likely they were to buy OTC weight-loss products or to diet. But upping the number of televised ads for prescription drugs increased the likelihood that women would try the advertised medication and made them more likely to diet.

When it came to print ads, women reacted a little differently. Researchers found that deceptive print ads were associated with a higher level of dieting, but not of OTC supplement use. Researchers speculated the deceptive statements could “lead them to seek substitute methods of weight-loss.”

Men are a different story. Deceptive print ads actually increased the likelihood that men would swing by the drugstore to pick up an OTC weight loss booster, but TV ads for prescription weight loss drugs made them think poorly about OTC weight-loss products.

Researchers also found that deceptive OTC print ads decreased the probability of exercise for both men and women.

The study was based on a survey of 26 magazines between 2000 and 2007 that ran print ads for OTC and prescription weight loss products and on TV ads that ran between 2002 and 2007.

Print ads appeared in every issue of the magazines, for a total of 466 unique print ads, and ran in publications including Better Homes & Gardens, Black Enterprise, Business Week, Money, Rolling Stone and Vogue, among others.

The TV ad data was based on 1,115 unique OTC weight-loss advertisements, which collectively ran almost 1.2 million times.