What is RED-S? RED-S stands for relative energy deficiency in sport. VIS Expert™, Emily Kraus, explains that RED-S is caused when athletes do not eat enough food to meet their energy needs. This leads to various health and performance consequences, such as bone injuries and the loss of a normal period.    For women in sport, low energy availability can occur intentionally or unintentionally. Let’s dive in and learn more about ways to identify this disorder.