Your Brain Starts to Eat Itself During a Marathon, Study Shows

When you run a marathon, it’s not just your legs that get exhausted. Your brain gets hungry too.

So hungry, in fact, that it starts feeding on itself, according to Videnskab.

That may sound dramatic — but according to new research, it’s actually a clever way for the brain to keep itself running when energy is low.

A new study has shown that marathon running can cause a temporary drop in a key substance in the brain called myelin.

Myelin is a fatty layer that wraps around nerve fibers. It acts like insulation, helping messages travel quickly between brain cells and to your muscles.

Researchers scanned the brains of 10 runners before and two days after a marathon. The results were surprising.

They found a 10 to 15 percent drop in myelin in areas of the brain that control movement. After two months, the myelin levels were back to normal.

So, what’s going on here?

The brain uses a lot of energy — more than you might think. During a marathon, the body’s energy reserves run low.

The brain seems to tap into its own myelin as an emergency fuel source.

According to Henrik Lundell, a senior researcher at the Danish Research Centre for Magnetic Resonance, this might be a built-in survival strategy.

He explains that although myelin is important for brain function, the body can rebuild it.

The loss after a marathon doesn’t appear to cause long-term harm. In fact, the brain constantly makes new myelin, even at rest.

Lundell notes that the scanning method used in the study measures myelin indirectly.

It’s possible that other changes — like shifts in blood or fluid levels — could also explain the results.

Still, the findings open up new questions about how the brain responds to extreme physical stress.

Does this mean marathons make you dumber? Probably not. There’s no sign that thinking ability is affected.

If anything, it just shows how incredibly adaptive the brain really is — even when it’s running on empty.