Good nutrition is one of the elements of training and conditioning necessary for optimal performance. The athlete should consume a diet composed of a wide variety of foods to help ensure that nutrient needs are met, whereas maintenance of ideal competitive weight is the indicator of adequate calorie intake. The best diet is one that considers physiological, sociological, and psychological factors--an individualized diet. The precompetition meal should consist of foods the athlete likes, tolerates well, and usually eats. The main nutrition consideration during the all-day meet is fluid replacement, and swimmers should be encouraged to drink ample water, especially when in a hot environment. Foods and beverages the athlete likes, taken in small amounts throughout the day, can ward off hunger, provide needed calories, help maintain blood glucose levels, and meet fluid needs. Although vitamins and minerals taken at levels in excess of the RDA have been shown not to benefit performance, use of high levels of supplements is not uncommon among athletes. Athletes are often unaware that some nutrients can be toxic when taken in excess.