( CNN ) -- Just what is it that separates a champion athlete from the also-rans ? Natural talent , hard work and determination are all essential , but athletes and coaches are becoming increasingly aware of the crucial role diet plays in sporting success . Olympic athletes are fueled by high-carb diets . Dr Samantha Stear is national lead for performance nutrition at the English Institute of Sport ( EIS ) and helped make the Beijing Olympics Britain 's most successful games for a century . `` A good diet is n't going to turn a mediocre athlete into a champion , but a champion eating a bad diet may just miss out , '' she told CNN . Training is the key to improving athletic performance , and the right diet is the key to sustaining a punishing training regime . Your body uses glycogen stored in the muscles to provide the energy needed for exercise , and the body makes that glycogen by breaking down the carbohydrates you eat . So carbohydrates are the vital fuel needed for training , and the more training an athlete does , the more fuel they need . Sprinters will often train for just an hour a day , whereas an endurance athlete will train for three hours or more . To sustain that level of training , sprinters need to eat around 5g of carbs per kg of body weight every day , whereas endurance athletes need at least 7g per kg . For Jamaican sprint sensation Usain Bolt , that means consuming some 450g of carbs a day , whereas , while Ethiopian distance demon Haile Gebrselassie would need at least 380g . Despite doing less training , Bolt would have to eat more carbs simply because he weighs more . So what 's the fuel of choice for these elite athletes ? `` In general , endurance athletes are better about getting a variety of carbs , just because they have to eat so many they get bored . They 're good at mixing up pasta , rice and potatoes , '' says Stear . Because `` strength-and-speed '' athletes do less training than endurance athletes , they have to watch their weight . Stear says sprinters often favor low glycemic-index carbs to help them keep their weight in check . What is the glycemic index ? Carb consumption becomes crucial when athletes are training more than once a day . Stear says it 's essential that athletes refuel between training sessions , otherwise they risk fatigue , which can weaken their immune system and make injury more likely . She also stresses the importance of refueling immediately after training , when the body restocks glycogen at a higher rate . When it comes to this kind of rapid refueling , athletes load up on high glycemic-index carbs , which the body can better convert to glycogen -- and then to energy . But man can not live by bread alone . Protein is needed for building and repairing muscle and is essential in the diet of athletes and non-athletes alike . Surprisingly , the protein recommendations for elite athletes are much the same as for regular folks . A confirmed couch potato needs about 0.75g of protein per kg of body weight per day , while someone doing regular activity -- about an hour of a day -- needs some 1.2g/kg . Endurance athletes need about 1.3g/kg and strength and speed athletes , with their extra muscle volume , need about 1.5g/kg . Even once the competition has begun , nutrition has a role in keeping the body working at its best . In endurance events , from distance running to tennis , the main danger for an athlete is dehydration . `` In a marathon the runners need to refuel and rehydrate and one of the best ways of doing that is with a sports drink . They provide carbs for fuel and there 's salt in there to help with electrolyte loss and help with the absorption of the water , '' says Stear . As well as eating the right food , athletes use a host of ergogenic aids to maximize performance . For example , some athletes use buffers such as sodium bicarbonate and sodium citrate to neutralize the lactic acid that builds up in the blood during exercise , fending off fatigue , while others choose to have a caffeine boost on race day . Stear says the EIS uses over 100 ergogenic aids to aid performance , as well giving athletes assorted anti-oxidants , fish oils and amino acids to boost their immune system . Diet is a serious business at the EIS , which employs 18 nutritionists . Although performance nutrition was only brought in to the set up in 2005 , it has clearly had an impact on British sport . At the 2004 Olympic Games Britain won nine golds -- at the 2008 games team GB won 19 . While nutrition alone can not take the credit for that remarkable improvement , when London hosts the Olympic Games in 2012 , the competitors will be all too aware the right diet could be the difference between gold and silver .
The right diet can be the difference between a gold and silver medal . Food intake is the key to sustaining a punishing training regime . A sprinter like Usain Bolt needs to eat 450 g of food each day . Rehydration with energy drinks is essential during endurance events .