input: [Recommendation] Fuel up [Why] 
output: Athletes have different calorie requirements, depending on the intensity of their training and performance. Calorie restriction can have many negative effects, so be sure to get enough fuel through calories. Calorie requirements for athletes depend on the intensity of their training and performance. The athlete who trains to exhaustion on a daily basis needs more fuel than one who performs a milder regimen two or three times per week. Calorie requirements can be as much as 23 to 39 calories per pound of body weight per day for the training athlete who exercises vigorously for several hours per day.3 , 4 Many athletes compete in sports having weight categories (such as wrestling and boxing), sports that favor small body size (such as gymnastics and horse racing), or sports that may require a specific socially accepted body shape (such as figure skating). These athletes may feel pressured to restrict calories to extreme degrees to gain a competitive edge.5 Excessive calorie restriction can result in chronic fatigue, sleep disturbances, reduced performance, impaired ability for intensive training, and increased vulnerability to injury.6