This Is What May Happen When Athletes Push Their Training Too Far

You finish a tough training session, shower, get on with your day, and realize hours later that you barely ate. Maybe your appetite has been low, or your schedule has been so packed that meals have become an afterthought.

It happens, especially when training gets more intense. But if that pattern continues, your body may not have enough energy left over for everything it needs to do beyond exercise.

Researchers pooled data from 11 existing studies to compare athletes with low energy availability (LEA) with those who were getting enough energy to support their training and normal bodily functions.

The analysis included 1,006 athletes, 471 women and 535 men. Researchers looked at body composition, bone density, and several hormone and health markers.

So, what exactly is LEA? In simple terms, it's a mismatch between the energy you take in and the energy you use during exercise.

Once your body covers the cost of training, there may not be enough energy left to support everything else it has to manage, including bone maintenance, hormone production, recovery, and immune function.

Just over half of the athletes in the analysis, 50.6%, were classified as having LEA.

Those athletes tended to have lower body weight and BMI, but the researchers also found differences that aren't as easy to spot.

Athletes with LEA had lower bone density scores and higher levels of cortisol, a hormone involved in the body's response to stress. Several other health markers were also lower, while leptin, which helps regulate hunger and energy balance, wasn't significantly different between the groups.

The bone findings are particularly relevant for athletes. Your bones are constantly being broken down and rebuilt, and that process requires energy.

If your body repeatedly comes up short, bone maintenance may not get the support it needs. Over time, lower bone density can contribute to problems such as stress fractures.

Cortisol is a little more complicated. It naturally rises during exercise and other stressful situations, so a higher level isn't automatically a problem.

But consistently elevated cortisol can signal that the body is under ongoing strain and may affect areas such as recovery and reproductive function.

LEA doesn't always announce itself. You may simply feel more tired than usual or notice that your workouts aren't going quite as well as they used to.

The practical message is fairly simple. When your training load increases, your energy needs usually increase with it.

That might mean adding a snack around a workout, making meals a little more substantial on harder training days, or paying closer attention to whether you're actually eating enough throughout the day.

Getting enough protein also matters for muscle repair and recovery, but protein is only one part of the equation. Your body needs enough total energy to support all of its functions.

This meta-analysis found that low energy availability was common among the athletes studied and was associated with lower bone density and higher cortisol.