A long-term study has found that men who eat more fat, including more saturated fat, are less likely than men on lower-fat diets to suffer a stroke.

The finding, which is supported by two prior studies in Japan and Hawaii as well as by experiments in laboratory rats, is the latest in a series of conflicting reports in recent years about how much and what kinds of fats are most healthful.Experts say the finding does not mean it is safe to indulge in a diet of hamburgers and other high-fat foods, or even in a fatty holiday meal, which can temporarily reduce the flexibility of blood vessels and may precipitate a heart attack in susceptible people.

Rather, they said, the study suggests that the Mediterranean diet - which is not low in total fat but contains little saturated fat and focuses instead on monounsaturated olive oil, fruits and vegetables - may be the healthiest diet of all. A previous report linked a high intake of fruits and vegetables to a reduced risk of stroke.

The new study, which is being published on Wednesday in The Journal of the American Medical Association, followed the fate of 832 initially healthy middle-aged men in Framingham, Mass., for 18 to 22 years to determine the relationship between their risk of stroke and the kinds and amounts of fats they typically consumed at the beginning of the study.

During the follow-up period, the men who were eating the highest fat diets in the late 1960s were least likely to suffer a clot-caused stroke, while those consuming the lowest amount of fat had the highest stroke risk. The association between high fat intake and low stroke risk was found for total fat, saturated fat and monounsaturated fat, but not for polyunsaturated fat, which can lower blood levels of cholesterol.

The study was directed by Dr. Matthew Gillman of Harvard Medical School among participants in the ongoing Framingham Heart Study, now in its 49th year. No similar study has been completed yet in women or elderly men, and the researchers said the findings in men might not apply to them.

Dr. Scott Grundy, director of the Center for Human Nutrition at the University of Texas Southwestern Medical Center in Dallas, said the results should be considered preliminary and questioned the validity of basing such findings on a single measurement of fat intake that was then projected over a 20-year period.