There is no doubt that our sense of smell is what makes the very act of eating pleasurable. Getting a strong whiff of our favorite food while it is being cooked definitely makes our mouth water, no matter how full our tummy may be. And scientists have found out, this is what causes all the trouble. Smelling food may make you obese.
Really smelling food can make us obese? Recently some experiments conducted at the University of California, Berkeley, have given scientists reason to believe that our sense of smell is closely related to our body weight. The experiments involved observing some obese mice that had their olfactory nerve cells temporarily destroyed using gene therapy. The results were astonishing. It showed that when put on a high fat diet, the obese mice that lost their sense of smell, lost weight despite eating the same amount as the other mice that still had their sense of smell. In turn, the latter section of mice ballooned up. Scientists also observed that, those mice that had a boosted sense of smell got even fatter than the rest.
The procedure that was used to temporarily destroy the olfactory neurons in the noses of the mice is known as the gene therapy. It destroys the nerve cells but keeps the stem cells so that the mice that lost their sense of smell would regain it as the neurons grow back in about three weeks.
No Smell, No calories
On the basis of their findings, scientists now strongly argue that the odor of what we eat plays a crucial role in whether our body chooses to store or burn the energy it gets from the food we eat. Even though it is hard to digest, the new found theory is that if you can’t smell your food, your body is probably not going to pack any calories.
The olfactory system is the part of our sensory system used for smelling. There is a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli. As we all know, the brain is the part of our body that controls our metabolism rate. So, it has to be concluded that there is a connection between the regions of the brain that stimulate metabolism and our olfactory system.
“This paper is one of the first studies that really show if we manipulate olfactory inputs we can actually alter how the brain perceives energy balance, and how the brain regulates energy balance,” said Céline Riera, a former UC Berkeley postdoctoral fellow now at Cedars-Sinai Medical Center in Los Angeles.
Recently, a related study was published in the journal, Cell Metabolism. The study shed light on how the loss of smell could have a direct implication on the loss of weight. It discussed the possibilities of interventions to help those who have lost their smell as well as those who face weight issues.
Sensory System and Metabolism
“Sensory systems play a role in metabolism. Weight gain isn’t purely a measure of the calories taken in; it’s also related to how those calories are perceived,” said senior author Andrew Dillin, the Thomas and Stacey Siebel Distinguished Chair in Stem Cell Research, professor of molecular and cell biology and Howard Hughes Medical Institute Investigator. “If we can confirm this in humans, perhaps we can actually make a drug that doesn’t interfere with smell but still blocks that metabolic circuitry. That would be amazing.”
Riera noted how mice and humans show similar sensitivity to the sense of smell. When they do not get the smell of food, the body is less tempted to eat or the body tricks itself into thinking that it has enough nutrition. While searching for food, the body takes precautions and stores calories in case unsuccessful. And once the body obtains food, it burns the calories.
However, as with all other things, there are side effects to this approach as well. The loss of smell leads to an increase in the levels of the hormone, noradrenaline. Noradrenaline is a stress response hormone that is related to the sympathetic nervous system. If the increase is drastic, it may even lead to a heart attack in humans.
“People with eating disorders sometimes have a hard time controlling how much food they are eating and they have a lot of cravings,” Riera said. “We think olfactory neurons are very important for controlling pleasure of food and if we have a way to modulate this pathway, we might be able to block cravings in these people and help them with managing their food intake.”
Further studies in this field of research, may lead to effective ways that could help obese people lose weight in a healthy way.
So, smelling food may make someone obese.