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.

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

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.

If athletes push themselves too hard for too long without enough rest, they can develop a serious condition called overtraining syndrome, where their performance gets worse and just won't improve — even after taking time off.

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.

Some scores that combine health, hormone, and body measurements might help tell the difference between male athletes who are overtrained and those who aren’t — but right now, there’s only one small study showing this.