In recent years fast food has been linked to the country's rising obesity rates and the increased incidence of diabetes. Findings presented yesterday at the annual meeting of the American Chemical Society in San Diego may provide a means of tempering the cuisine's ill effects: an additive that can slow the absorption of fat to a healthier rate.

Wallace H. Yokoyama of the United States Department of Agriculture and his colleagues fed a group of hamsters a diet with a fat content similar to that of typical American fast food--that is, with about 38 percent of its calories derived from fat--for four weeks. A second group of animals ate a low-fat diet with 11 percent of the total calories coming from fat. At the end of the study period, the high-fat eaters developed insulin resistance--a precursor to diabetes--whereas the control animals did not. The initial results corroborated previous findings in similar studies. But when the scientists repeated the experiment with the addition of a cellulose derivative known as hydroxypropylmethylcellulose (HPMC) to the high-fat food, the animals on that diet did not develop insulin resistance.

HPMC is already used as a food additive to modify the texture of items such as fillings, sauces and glazes. To achieve similar fat-fighting results in humans, much larger amounts (about five grams per serving) would be required, the scientists propose. The mechanism for HPMC's beneficial effects remains unclear, although Yokoyama posits that the compound works to slow down the absorption of fat by the digestive system. The results, which are preliminary, are not a panacea for fast-food devotees, however. "Obviously, the less fat you eat, the better off you are," Yokoyama says. "But if you're going to eat high-fat foods, then adding HPMC to it might help limit the damage."