This Runner Staple May Be Making You Smell

Research finds a connection between what you eat and how you smell.


Here’s the scene: you’re at your local group run when you spot the cute guy who chatted you up a few weeks ago. At the end of the run, you flag him down. He’s handsome, funny and charming. But for whatever reason, that spark is missing.


What’s the problem? It could be that he’s been carbo-loading.


Okay, stay with us here: It turns out that what you eat may affect the smell of your sweat. For runners who like to be social after a group run, that could be an issue. A study published this month in the journal Evolution and Human Behavior found that women preferred the scent of a man’s sweat whose diet was rich in fruits in vegetables. Sweat from those eating a diet high in carbs? It was deemed “less pleasant.”  


This study builds on previous research about how diet may affect mate choice. Andrea Zuniga, a researcher at Macquarie University in Sydney, and the lead researcher for this paper, says that diets high in carotenoids – which are often found in fruit and vegetables – can give our skin a healthy orange tint (it’s a subtle glow, not the bright orange of one too many tanning salon visits). In studies, this tint has been proven to be attractive to members of the opposite sex.


Zuniga wondered if a diet high in fruits and veggies might translate to more attractive-smelling sweat too. For this study, 43 males were asked to wear a cotton T-shirt for 24 hours without bathing – including one hour of exercise. The shirts were then sealed in plastic bags and frozen until a group of women was put together for a sniff test.


The researchers used men as the shirt-wearers and women as the sniffers for a few reasons. First, according to science, men sweat and smell more. Second, when polled, women tend to rate smell as a more important characteristic of attractiveness than men do. Women are also more sensitive to smell than men, generally doing better on olfactory tests.


Nine women sniffed the sweaty shirts and rated how pleasant or unpleasant the garments smelled. Actual descriptors the researchers asked the women to use included: animal, burnt/smoky, chemical, coffee, earthy, egg, fishy, floral, fruity, garlic/onion, meaty, medicinal, nutty, oily/fatty, soup, sour, spicy, sweet, tobacco, vegetative and yeasty. Each of these characteristics was then deemed either a good smell or a bad one. Animal, meaty, and oily, fishy, egg, garlic and yeasty smells were considered good, while floral, fruity, sweet and medicinal were bad.


Vegetarians, or those who had diets rich in fruits and veggies smelled the best. Men with diets high in fat and protein smelled pleasant too. But those with high-carb diets smelled the worst.


So should you change your diet in hopes of smelling better? The answer is no. According to Tara Gidus, a registered dietitian, “if you cut out carbs just to smell better and end up hitting the wall during exercise or having bad breath because of a high-protein-low-carb diet and ketosis, that won’t leave a very good impression”. (“Keto-breath”, or foul smelling breath is a well-documented side effect of your body entering ketosis during a low-carb diet. So your sweat may smell better, but your breath won’t.)


Alissa Rumsey, a spokesperson for the Academy of Nutrition and Dietetics, noted: “carbohydrates, specifically glucose, give your muscles energy during a run. Glucose turns into energy that helps contract and propel your exercising muscles. During long runs, fat is another important nutrient that you use for fuel, however, you need glucose on board in order to optimally burn fat.”


Of course, this study did find those who consumed lots of fruits and veggies smelled the best, and that’s something both dietitians can get on board with.


But it’s important to remember that this is just one exploratory study – the researchers say more research is needed.


“While previous research has found that women report how a man smells to be an important factor in attractiveness judgments, more research is needed to establish whether women actually use smell when selecting partners,” said Zuniga. “It is also uncertain how smell interacts with other sources of information about attractiveness, such as vision, touch and sound.” The study also relied on self-reported info on diet – a measure that is chronically unreliable.


Bottom line: don’t change your diet, though consider adding in more fruits and veggies. And if that cute guy at the run is a little smelly post-workout, cut him some slack. He’s probably just well-fuelled.




Related Articles