Indulging in even the occasional saturated fat-filled mealcan be harmful to your health and lower your body’s ability to fight heart disease, say researchers in Australia. In a recent study, they examined the effects when healthy 18 to 40 year olds ate just one piece of carrot cake and drank a milkshake. Researchers found that even one fatty meal diminished the ability of “good cholesterol,” or HDL, from protecting the participants’ arteries from the build-up of fatty plaques that can clog blood vessels.