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A big part of the pleasure we derive from food has to do with its smell. What's better than the smell of muffins straight out of the oven or garlic cooking on the stove? Therefore, it's no surprise that the amazing smell of certain foods can cause us to overeat them. But what would surprise many us is learning that our sense of smell can cause us to gain weight—regardless of how much food we actually consume. Puzzling though it may be, new research published in the journal Cell Metabolism, suggests just that.
Does sense of smell lead to weight gain?
In this study, scientists from the University of California–Berkeley injected mice with a toxin that caused them to temporarily lose their sense of smell. Then, they put the smell-deprived mice on either a normal healthy mouse diet or a high-fat junk-food mouse diet. After three months they compared them to mice with intact senses of smell that had been following the same diets. Turns out the smell-deprived mice on the normal diet weighed slightly less than those with a sense of smell. Interesting, right? What's even more interesting is that the mice on the fatty diet who couldn't smell weighed a whopping 16 percent less than those that could.
It's logical to assume that the smell-deprived mice were simply eating less, but the results showed that both groups were eating the same amount of food throughout the study period and all mice maintained the same amount of physical activity. In other words: Losing their sense of smell protected mice from the weight gain associated with the unhealthy diet.
What does this mean about metabolism?
The surprising results of this study suggest that sense of smell might play a direct role in physiological energy balance and metabolism. When looked at more closely, the data revealed that the mice without a sense of smell actually burned more calories in their brown fat (the good kind that is capable of converting fat to energy). They also converted more white fat (the fat you don't want) to brown fat, suggesting that the lack of smell was able to rewire the metabolism at its very core.
This newfound connection between sense of smell and metabolism is just one more reason to believe that weight is way more complicated than simply counting calories—that it's not just about how much you eat but how you interact with and perceive food. Researchers think this could be an interesting avenue for fighting obesity in humans, assuming that our metabolisms respond the same way to temporarily losing our sense of smell.