Some physically active people are at risk for Relative Energy Deficiency in Sport or RED-S. This often unrecognized disorder can include low energy availability (inadequate caloric intake); with or without disordered eating; amenorrhea (lack of menstrual periods); and low bone mineral density.
It's important to know that, in the context of Relative Energy Deficiency in Sport, disordered eating includes both intentional and non-intentional under-consumption of calories. This can occur both as a function of poor eating habits and as a function of too intense exercise.