One of the many myths in sport nowadays concerns diet: to achieve the necessary muscle growth and strength for sport - especially at an elite level - you must eat meat. It's a belief that's been around a while. Sportsmen in the 1800s, for instance, consumed huge amounts of raw eggs and steak right before competitions. Even today, surely no athlete would dream of eschewing meat in favour of a plant-based diet. Not only would this make them sick or weak, but their bodies would lack the critically important macro- and micro-nutrients required to achieve peak performances, such as protein, iron, vitamins B12 and D and calcium. Right? In the highly competitive world of elite and professional sport, a properly balanced diet is still an effective method of achieving an optimal level of fitness. Contrary to some of the more popular diets today that vilify carbohydrates, most sports nutritionists say complex carbohydrates, rather than protein, should be the backbone of an athlete's diet. Protein alone just isn't sufficient to meet the demands of competing. But eating only carbohydrates (complex or simple) isn't enough, either, because without protein an athlete will most likely become sick, lose stamina and energy. So, a balanced diet is essential. What should you eat to achieve this balance? Most elite athletes still meet their protein requirements by eating meat. But an increasing number from all sports, including swimming, skiing, cycling, running, tennis and triathlon, are choosing plant-based diets. Lisa Dorfman, the author of The Vegetarian Sports Nutrition Guide, says a vegetarian diet can be 'the body's best fuel'. Some athletes, especially women, switch to vegetarianism as a means of restricting calorie intake to become leaner for their sport. But Dorfman says being vegetarian alone isn't enough to get you into the next Olympics. Vegetarians tend to have lower protein intakes than omnivores. What's important is to know how to replace the protein grams found in meat to provide the body with enough nutrients and energy sources for healthy muscles and peak performances. According to the American Dietetic Association (ADA), the protein quality of a vegetarian diet is adequate for adults, but plant proteins aren't always as well digested as animal proteins. To compensate, the ADA recommends protein intake for vegetarian athletes of between 1.3g and 1.8g per kilogram of body weight. One of the more popular and efficient methods of achieving this amount of protein is by combining non-meat protein sources such as grains, pulses and legumes. According to Dorfman, other good sources are dairy and soy because 'they contain the same nine essential amino acids found in fish and meat, making them equally good sources of complete proteins'. But protein isn't the only nutrient a vegetarian athlete has to be concerned with. Vitamins B12, C and D, riboflavin, calcium, zinc and especially iron are vital, particularly for female athletes. The American College of Sports Medicine recommends vegetarian female runners have their iron levels screened occasionally to see if they're low. The best way for vegetarian athletes to avoid deficiencies, Dorfman says, is to consult a sports nutritionist about taking supplements. She says that, as long as the athlete plans the diet carefully, a vegetarian diet can provide all the nutrients needed to achieve peak performances. 'Being a vegetarian athlete isn't about what you don't eat, but what you do,' Dorfman says.