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Your Nose Knows Which Foods Are Fattiest

Charles, Prince of Wales, smells before tasting some ice cream during a visit to Gloucestershire. Maybe he was sniffing for fat?
Barry Batchelor/Getty Images
Charles, Prince of Wales, smells before tasting some ice cream during a visit to Gloucestershire. Maybe he was sniffing for fat?

A lot of us can agree that low-fat ice cream is a sad substitute for the real deal. It's not as creamy, and it just doesn't taste as good.

Now researchers are saying it may even smell different.

Researchers from the Monell Chemical Senses Center have found that people can actually smell differences in dietary fat in food.

The researchers had 108 participants in Philadelphia and the Netherlands sniff samples of milk with different amounts of fat. Once the results were tallied up, it was clear that the participants could actually distinguish among the samples based on their fat content.

The study was published this month in the journal PLoS ONE.

Psychologist Johan Lundström, the study's lead author, says the findings make sense because, "from the evolutionary point of view, you need energy to survive." And fatty, high-calorie foods are a great source of energy.

In our caveman days, "detecting fat would have been very valuable for us," Lundström tells The Salt. A quick sniff and you'd know which foods had more of the calories we craved.

Lundström says he doesn't think that the ability to smell fat is a learned skill. For one thing, participants from the U.S. and the Netherlands were equally good at sniffing out fat, even though the Dutch drink a lot more milk than Americans, he says. The participants' weight didn't affect their abilities, either — overweight participants did the same as everyone else in the sniff tests.

And Lundström says he's confident in this study's results. The researchers made sure they were isolating just the fat in milk by using powdered milk rather than the farm fresh stuff.

"The only thing that these powders differed in was the amount of fat," Lundström. "Otherwise, the samples are identical." And each bottle of milk the participants sniffed had the exact same concentration of powder.

The findings build on previous studies that showed humans can smell fatty acids in their pure form. The next step, Lundström says, is to see whether we're able to isolate the smell of fat in more complex foods like burgers.

There are a lot of other unanswered questions as well. For one, Lundström says, we don't know how we're able to smell the fat.

"Fat molecules in milk are not very volatile," he says. "In other words, they are not very likely to fly around in the air so you can smell them."

It is possible that the fat molecules attach themselves to other compounds that do like to stink up the air, Lundström says.

And while the study makes it pretty clear that humans are able to smell different concentrations of fat, what's not yet known is how that ability affects our behavior, Lundström says.

Do people crave foods that smell fattier? Or do those smells help keep us from overeating? Those are the kinds of questions scientists must still figure out, Lundström says.

The answers could be key in helping us step away from that tub of Ben & Jerry's in the freezer.

Copyright 2021 NPR. To see more, visit https://www.npr.org.