Alimentación, movimiento y sueño
Under-fuelling and lost periods (RED-S)
Revisado: 4 de octubre de 2026
Solo en inglés por ahoraIf you do not eat enough to cover the energy you use, your periods can become irregular or stop. Lost periods are a warning sign worth getting checked.
What RED-S is
Relative energy deficiency in sport (RED-S, also written REDs) happens when, over time, you do not eat enough to cover the energy your body uses, including for exercise. It affects men as well as women. A related, older term, the female athlete triad, describes three linked problems: not eating enough for your activity, missed periods and weak bones. RED-S is a broader idea that covers many effects on health and sports performance.
How it can happen
RED-S can happen without anyone meaning it to. You might start training more without eating more, or train more while also eating less. It is more likely in sports where being thin is seen as an advantage, such as distance running, gymnastics, figure skating, dance and rowing. Training a lot in one sport from a young age, or feeling pressure to lose weight, can add to the risk. Sometimes it is linked to an eating disorder, and sometimes it is not.
Effects on periods and bones
When energy is low, a part of the brain called the hypothalamus can slow or stop a hormone that the cycle depends on. Oestrogen levels drop. Cycles may get longer or less regular, and periods may stop altogether. Low oestrogen, poor nutrition and too little calcium or vitamin D can cause bone loss. This makes stress fractures (tiny cracks in a bone) more likely. Over time, bones can become weak enough to break easily (osteoporosis).
Other effects
RED-S can affect your health and your sports performance in many ways, not only your periods. Broken bones and other sports injuries can become more common. Mood can be affected too, and low mood, anxiety or depression can come with RED-S. These signs are worth taking seriously, even if your periods have not stopped.
Treatment and recovery
Treatment means closing the gap between the energy you take in and the energy you use. That usually means eating more, training less, or both. Getting enough calcium and vitamin D also helps protect your bones. Care often comes from a team, which may include a doctor, a dietitian, a mental health professional and a coach or trainer. If disordered eating is part of the picture, treatment will include support for that too. Recovery takes time, so it helps to start early.
When to see a doctor or nurse
Losing your periods is a warning sign, not a normal part of training. See a doctor or nurse if your periods stop or become irregular while you are training or eating less. Also go if you are 15 or older and your periods have not started, or if you have a stress fracture or keep getting injured. Logging your periods and activity in Ciclo can help you spot changes early and show a doctor what has happened.
This is general information, not a diagnosis. If your periods have stopped, talk to a doctor or nurse.