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The Science of Runner Stink: Why Some People Smell Like Ammonia Post-Run

It’s a familiar, pungent odor (associated with bleach and smelling salts) that’s hard to brush off. Here’s what’s really happening to your body.

Despite having a chaotic diet and exercise regime, I’m happy to report that my body odor remains largely the same when I work out. It’s not a great stench, but it’s consistent enough that my wife implicitly knows when I’ve come back from a run and how quickly I should get into the shower.

I consider this dependable stank a health win, since not all runners — or anyone who exercises — can say the same. Worse yet, on forums like Reddit’s r/running, panicked runners report reeking of ammonia at the conclusion of their run, a familiar, pungent odor (which is mostly associated with bleach and smelling salts) that’s hard to brush off.

After a long run and I smell..Ammonia? from running

Ammonia smell after running from C25K

Why do I smell ammonia after I’m done running? from running


Mainly because their bodies have run out of carbohydrates to burn for fuel, so they switch gears and start burning protein instead. “Proteins are made up of amino acids, and when metabolized, they can be partially converted into glucose to provide an energy source for the working muscle,” explains William Roberts for Runner’s World. However, one of the byproducts of this process is ammonia, which, in normal circumstances, would be broken down in the liver and flushed out via urine.

But because your body is now producing more ammonia than normal, the only way to get rid of it is through sweat. Though hardcore keto bros may argue this is a sign of ketosis, meaning your body is burning fat and protein instead of carbs, most medical professionals advise people who smell like ammonia after working out to hydrate and eat a few carbs (even if you’re on a low-carb diet). “If you’re smelling ammonia in sweat, something’s wrong,” explains Lewis Maharam, author of Running Doc’s Guide to Healthy Running, in an interview with Time. “Balance is the key to health, especially when it comes to what you’re eating. Going to the extreme of all protein or all fat or all carbs — none of those is good for you.”

If upping your carb intake doesn’t alleviate the problem, Maharam recommends seeking professional medical help, as it may be a sign of liver or kidney disease.

Otherwise, smelling like ammonia after one or two workouts isn’t a death sentence — again, so long as you hydrate and adjust your diet accordingly. Besides, putting your body through the stress of emergency-flushing toxins like ammonia on a regular basis doesn’t exactly put you on the path toward long-term health. It’ll mostly just make you smell like shit.