Not eating enough calories or carbs can lead to serious health and performance problems in athletes, like burnout and hormonal issues.

If athletes don’t eat enough calories or carbs, especially during intense training, they might not recover well—and fixing that could stop them from feeling overly tired or burned out, which people often think is overtraining.

Some athletes who are told they're just overtrained might actually be low on fuel — their bodies aren't getting enough energy or carbs — which can look like overtraining but is really a different condition called RED-S.

To diagnose overtraining in athletes, doctors need to rule out other health issues like low nutrients, infections, or energy deficiency, because those can cause similar symptoms and often happen at the same time as overtraining.

If athletes train too much and don’t eat enough, they might be misdiagnosed with overtraining when the real issue is low energy from not fueling properly.

Low energy levels in athletes might help explain why some get overtraining syndrome, but it's not the only reason — other factors like brain fatigue and body inflammation could also play a role.