A Food Lover's Guide To Fat

Maybe. maybe not. a low-fat diet used to be considered one of the best steps that women could take to protect against breast cancer. Then along came 89,494 nurses, participants in a huge study of diet and health headed by Walter Willett, chair of the nutrition department at the Harvard School of Public Health. In 1992 Willett and his colleagues published the startling results of the breast-cancer phase of the study: researchers found no relation between how much fat the nurses ate and their incidence of breast cancer. Suddenly, fat was out of the picture as a risk factor for breast cancer; Harvard said so.

Since then, however, a few nutrition scientists have begun to warn against taking the nurses' study as the last word. Several note that most of the nurses' diets got more than 30 percent of calories from fat, a level that critics say isn't low-fat at all. ""Even the people, including me, who think fat is likely to be important in breast cancer think you have to go to 20 percent,'' says Greenwald.

Other researchers are looking at the possibility of more subtle, and in some ways more troubling, relationships between dietary fat and breast cancer. ""It's possible we've been studying dietary factors too late in life,'' says Tim Byers, chief of the chronic-disease-prevention branch at the division of nutrition in the Centers for Dis-ease Control. ""We have indirect evidence that nu-trition early in life may be more relevant.'' The is-sue is what's called ""overnutrition'' -- the high-fat diet of American kids, the same diet that makes second-and third-generation Asian-Americans taller than their parents. Many studies have shown an association between height and breast cancer: tall women have a greater incidence of the disease. A relatively early age at menarche, or first menstruation, is also associated with breast cancer. Both of these factors are determined in part -- although only in part -- by childhood eating patterns. Nobody advises restricting the diets of children under 2, but many experts now say that older children should aim for the same goal as adults: 30 percent of calories from fat.

Is cutting fat the best way to lose weight?

The percentage of fat you eat doesn't seem to make much difference.'' (Walter Willett)

""Obesity is caused by too many calories. Fat's a good place to begin.'' (Marion Nestle)