填空题. A．average B．tracking C．represses D．fuel E．at the expense of F．plummet G．presumed H．for the sake of I．consumed J．nutrition K．tedious L．suppresses M．strenuous N．nuisance O．performance Recreational runner Carrie Johnston usually doesn't feel hungry after a good sweat. Exercise 21 Johnston's appetite, but she knows she needs to make up lost calories following a workout. "When I come home from a good run, I force myself to eat supper," says Johnston, a dietitian at McMaster University in Hamilton. However, Johnston says many female athletes let good eating habits go and risk health 22 thinness. Johnston, who works in the bone-marrow transplant unit at McMaster, has a background in sports 23 . In 1997, while a student at the University of Guelph, she worked with Prof. Heather Keller on a study for her thesis on the eating habits of female athletes. The 24 person with eating disorders is driven by a desire to look svelte, says Johnston. But her study focused on athletes who eat less to lower weight and body fat based on the belief that it will improve 25 . The study involved 26 22 elite female athletes between ages 15 and 25 over three months. "Years ago when we didn't know any better it was thought that being lighter meant running better," says Johnston, adding that's still the mentality of many competitive runners, as well as other athletes like gymnasts and swimmers. Johnston's study subjects 27 400 to 700 fewer calories daily than recommended for their 28 training. Even when training more as they got closer to competition, they failed to take in more food 29 for energy. Initially, race scores tend to improve when a runner loses some weight, but then they hit a peak and 30 , says Johnston.