Carl's Jr. and Hardee's ads starring nearly naked women have become a part of American culture, according to Andy Puzder, CEO of the chains' parent company.

"People watch for the ads, and want to know when the next one's coming out," he says.

Some of the women were relatively unknown before they appeared in the ads. Others, such as Heidi Klum and Padma Lakshmi, were already famous. The 64-year-old chief executive says the ads "cut through the clutter" and make an impression on the younger men the burger chains court.

CKE Restaurants, the parent company of Carl's and Hardee's, is privately held and doesn't disclose financial results. But it says sales were up 5 percent at established locations in the second half of its last fiscal year.

The newest ad airs Monday and stars Sports Illustrated model Samantha Hoopes eating "The Most American Thickburger," which includes a beef patty between a split hot dog and potato chips.

-- Associated Press