Why do I smell so bad?

If you’re a long-distance runner, you’ve probably asked yourself this question. Perhaps you’ve been asked by loved ones; my own darling is uncharacteristically indelicate when it comes to my musk after a long run.

I say long run because I’m not talking about the normal sweaty body smell that I have after 5 miles. I’m talking about the stench that I have after 20 miles in the sun. It’s entirely different from normal sweat. It’s like I’ve been bathing in vodka, like my sweat will kill bacteria and remove stubborn grass stains.

I never thought much of it. This is what my body does when it’s been pushed to the limit. It wasn’t until I came across this article on Kevin Sayer’s site that I found out that this is an indicator of something unusual.

When we go on long (long, long) runs, we deplete the glycogen stores in our livers. Dehydration, excessive strain, and low carb intake speed up this process. Eventually the body no longer can rely on carbohydrates for energy, so it turns to the fat we’ve built up. This state is called ketosis. Ketones are produced as a waste product of fat-burning, and this acid starts to pollute your blood. It’s not dangerous (see here) until the ketone levels get too high, when their acidity can damage organs. Even a slightly elevated level of ketone, however, can cause muscle damage (Eades). It’s one of the reasons why elite runners tend to be disgustingly skinny.

Exhibit A: Paul Amey, kickass triathlete

If there’s a lesson in this, it’s to eat your GU– and please, never run long mileage on a low-carb diet. Americans have developed the idea that carbohydrates are bad and fat must be lost. But runners particularly need slow-burning carbs, and plenty of them, if they want to recover quickly and minimize muscle loss.

And not stink. That too.