Good news for high-mileage runners: They may be able to help themselves to an extra serving at holiday meals because variations in diet are less likely to affect them, researcher say. The new study included nearly 107,000 runners who were grouped according to the distance they run each day: less than 1.2 miles (under 2 kilometers [km]); 1.2 to 2.4 miles (2 to 4 km); 2.4 to 3.7 miles (4 to 6 km); 3.7 to nearly 5 miles (6 to 8 km); and about 5 miles (8 km) or more.