Sports nutrition is the specialised nutrition that fuels professional and serious amateur athletes, designed to provide enough energy for very active lifestyles and the nutrients that support tissue growth, repair, and recovery. It periodises eating around training: carbohydrate to fuel sessions and refill glycogen, protein timed to maximise muscle repair, fluids and electrolytes to replace sweat losses, and micronutrients to cover the elevated demands of heavy training. Body composition goals add further precision. The field blends physiology, biochemistry, and practical feeding, since the perfect plan fails if the athlete will not eat it. From the marathoner’s carbo-loading to the lifter’s protein targets, sports nutrition turns food into a performance variable.