Hamburgers appear on a grill in Washington on Aug. 4, 2011. Most grillers recommend a mixture of 80% beef to 20% fat, but Craig “Meathead” Goldwyn, author of “Meathead, The Science of Great Barbecue and Grilling,” prefers even more fat, up to a 70:30 ratio. (AP Photo/Carolyn Kaster, File)