What we eat doesn’t simply determine our internal health, it may determine our sexual attractiveness to the opposite sex.
A study by psychology researchers from Macquarie University found that men who eat a diet rich in fruit and vegetables smell more attractive to women than men who eat a high-carb or high-fat diet.
While it may sound outlandish, it makes evolutionary sense, says co-author, Dr Ian Stephen.
“We’ve known eating fruit and vegetables makes you look more attractive,” explains Stephen, who studies evolution, genetics and psychology.
A healthy diet keeps our waistlines in check but fruit and vegetables also contain yellow/red pigments, carotenoids, which are good for our immune system and reproductive system.
“They get deposited in the skin and give us a slightly golden colour that makes us look more attractive,” Stephen adds. “We also knew that odour is important for attractiveness too. Especially women smelling men, odour seems to be particularly important.”
The hypothesis is that men and women tend to value different characteristics in the opposite sex and as well as what we eat, our genes (“in particular a genome … which essentially codes for your immune system”) affect the way we smell.
“People who have genes that are good for your immune system tend to be perceived as smelling better … in the literature there has been a whole load of thinking around whether these immune genes are particularly valuable for women, so it’s possible that women are particularly sensitive to the way men smell because of this reflection of genes,” Stephen explains.
So Stephen and his colleagues decided to put the pieces of the attraction puzzle together.
“Seeing as we know that diet influences how we look and is important to health, we thought we would see if that’s something that would work in odour as well,” Stephen says.
If it worked, it would help to prove the “evolutionary theory” that beauty is not “arbitrary” and only in the eye of the beholder, Stephen said.
“For this evolutionary paradigm to work, it has to be the case that what we find attractive is related to some aspect of our underlying health and underlying fertility and so-on,” he explains.
To test the theory, 43 non-smoking Caucasian men aged between 18 and 30 filled out detailed dietary questionnaires and had the pigment in their skin measured by a spectrophotometer.
“Essentially the yellow components of your skin colour is a really good predictor of what you’ve been eating in terms of fruit and vegetables,” Stephen says.
The men were then given plain, white T-shirts to wear for 24 hours (without deodorant or aftershave) and instructed to go for a run and work up a sweat before delivering them back to the researchers.
After cutting out the smelly armpits of the shirts, the researchers gave the cutouts to the 10 female participants to smell and rate.
“They made a couple of different judgments on the odours, rating how attractive/pleasant they smelled and used a smell description inventory often used by sommeliers where you essentially rate how chemically it smells, how floral and how burnt it smells,” Stephen says.
“Whatever you eat contributes to the chemicals that come out of your skin and the way you smell is essentially a product of the chemicals that come out of your skin through sweat and sebum.
“The bacteria that live on your skin then digest those chemicals – it’s essentially a metabolic output of the bacteria is what you smell and that is affected by what they eat.”
Men who ate more fruit and vegetables smelled more floral and more attractive than men who had been eating more refined carb-heavy food (which smelled more musty and less pleasant or attractive).
Of the fruit and vegetable-intake men, those who ate a lot of fish smelled less attractive than those who ate more meat, eggs or tofu.
“I’m not too sure what I make of that – it’s an interesting one,” Stephen says of the fish finding.
Certain inconsistencies aside (we also do not know if the odour/attraction factor applies to same-sex couples) essentially, our smell reflects our diet, which affects our appeal.
Stephen believes that not all evolutionary health traits go together, which may explain the huge diversity of beauty among us.
“Skin colour could reflect your diet while voice reflects testosterone levels while body fat might reflect some other component,” he says. “It’s possible to be healthy in some ways and unhealthy in others.”
He adds that more research is still needed to solve the age-old question of attraction, but they are satisfied with their results.
“We answered the question that we set out to answer,” he says. “The answer was that there does seem to be a connection between odour and how attractive people smell and the underlying health of the diet they are eating which suggests that people are using odour as what we would call a valid cue to health – we use it to judge people’s health and there is some relation to how healthy they really are.”
And the message for us all?
“Attractiveness is very closely related to health and if you want to improve how attractive you are there are things you can do about it and those are the same, boring things doctors always say which is eat some fruit and vegetables and do some exercise.”