In brief This study describes the diets of female swimmers and assesses the effects of a liquid supplement. The self-selected diets provided more than the recommended dietary allowances (RDA) of food energy and six nutrients and less than the RDAs of vitamin D and iron. Consumption of the liquid dietary supplement increased the intake of all nutrients except cholesterol and increased the frequency of food intake. More frequent food consumption may improve performance by increasing alertness, avoiding hunger discomfort, and decreasing the rate of lipogenesis. A liquid dietary supplement is one way to improve the nutritional quality of athletes' diets and increase the frequency of food consumption.