Athletes utilize numerous strategies to reduce body weight or body fat and to increase stamina prior to competition. Personalized nutrition in athletic populations aims to optimize health, body composition, and exercise performance by targeting dietary recommendations to an individual's genetic profile. Additionally, athletes’ nutritional requirements may vary widely depending on sport, position, timing of season, and training vs rest day. Bodily hydration during sporting activity is one of the best indicators of health in athletes and can be a limiting factor for sport performance. Treatment for athletes is primarily to increase energy availability and often requires a team approach including a sport physician, sports dietitian, physiologist, and psychologist. Maximizing athletic performance is a passion that athletes, coaches, athlete support professionals, and sports scientists share. A thorough understanding of the basics of all aspects of human physiology and the ability of the body to adapt to the environmental stress of exercise training is the foundation we use to explain the incredible athletic and sport performances that are commonplace in today’s world.