As if losing weight wasn't hard enough already, a study by UC Berkeley researchers suggests that just smelling food can make you gain weight. Or at least, smelling food may make mice gain weight.
In their study, researchers Andrew Dillin and Celine Riera observed three groups of mice with various senses of smell. A control group with a normal sense of smell, and then "super-smellers," and mice without a sense of smell.
The two researchers fed all the mice a high-fat diet and noticed a correlation between sense of smell and the amount of weight the mice gained. The "super-smellers" gained the most weight, while those with a normal sense of smell gained up to 100 percent body weight, and those that couldn't smell at all gained only 10 percent on average.
The study also found that obese mice who had their sense of smell removed were able to quickly slim down to a normal size without a change in their diet.
Riera explains that after eating, a person's sense of smell decreases to make food less appealing and prevent us from overeating. If a person was eating with an already lessened sense of smell, the brain may be tricked into believing that it's already been fed and burn the calories straight away rather than store them as fat. Riera explains in the journal Cell Metabolism that the study proves outside influences can affect the brain’s function when it comes to appetite and metabolism.
The researchers hope that the study could be utilized to combat rising levels of obesity in humans. But they'd need to prove that it works on humans, and that comes with risks.
“People that don’t have a sense of smell can get depressed, because the sense of smell is very important for behavior,” Riera explained. “They lose all pleasure of eating.”
Riera went on to add that people who lose their sense of smell through disease, such as Parkinson's, can quickly drop to dangerously low weights.
The mice who had their sense of smell removed also had increased levels of the hormone noradrenaline, which can lead to heart issues if levels are too high.
Dillin, an expert in stem cell research, believes that the safest method of applying this to humans, if it was found to be beneficial, would be to destroy olfactory neurons in the nose but leave their stems cells intact. This would mean that a person's sense of smell would be restored within three to eight weeks. Dillin thinks that using this method on obese patients, along with a diet, could help weight loss.