Can Your Sense Of Smell Impact Your Weight?

July 17, 2017

blog_smellSometimes clinical research studies can seem really far out there, like the one that attached long weighted sticks to the rear ends of chickens to gain insight into how dinosaurs walked the earth. Or hilariously obvious, like the Journal of American Medicine’s “Study shows a beneficial effect of electric fans in extreme heat and humidity.” Hmmm…


There are still others that fall somewhere between the two, like a recently published study out of The University of California – Berkley centered on how the sense of smell impacts weight and metabolism in mice. The researchers found that mice with impaired olfactory abilities (i.e., could not smell well or at all) demonstrated the increased ability to lose and control their weight versus their full-smelling counterparts, who showed weight gain.

While the researchers expected to find a correlation between impaired smell and weight control (the more obvious part of the study), they were surprised about the mechanisms working behind the scenes that produced the outcome. One of the most unexpected findings was that the impaired mice became fat burning machines and experienced no deterioration in health status without reducing their fat consumption.

One of the theories behind the results is linked to the role the sense of smell plays in survival. In the animal kingdom, the ability to detect smells can mean life or death. If a predator is right around the corner, its scent is usually the first clue. But without the benefit of a sense of smell, animals (in this instance, mice), must rely on other means to stay alive. They naturally kick into a high state of alertness for longer periods of time. This in turn raises their noradrenaline levels higher compared to mice with a full or enhanced sense of smell. With elevated noradrenaline, their bodies essentially become fat burning machines.

Another theory is that sensitivity to food smells naturally decreases after eating a meal. The lack of the ability to smell may actually trick the mice’s brain into thinking they have already eaten.

Like most research studies, the results lead to even more questions. And when the subjects of the original research are mice, the logical big question is what kind of application might this have on humans struggling with weight, if any?

This is where the “far out” aspect of the research comes into play. In order to produce a valid sample of smelling-impaired mice, the researchers temporarily removed their sense of smell through gene therapy. This of course brings up all sorts of ethical questions (for both animals and humans), as well as whether humans would be willing to give up their sense of smell in the first place! In addition, it is thought that persistent increased noradrenaline levels in humans would increase the risk of heart attach. There have also been many cases where people who lost their sense of smell as a result of injury or aging experienced weight loss, but it is possible that the reduction may have been the result of depression.

While we are far from the reality of “no-smell weight loss” solutions for humans, the one immediate benefit we might take away from this research is the awareness of the relationship between smells and food. By understanding that there is a direct relationship between our ability to smell and weight gain, we can stop ourselves for a moment when seduced by the aroma of baked bread or a breakfast with bacon. It is in that one moment of awareness we can say to ourselves, “I know how this works. You can’t trick me, body!” and make a choice as to how much we eat. Ultimately you are in control of your choices and not at the mercy of your biology.






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