None of this means you should deliberately ditch your sense of smell as a quick weight-loss trick, but the research suggests weight loss and weight gain goes beyond how much you eat.
Mice lost more weight when they were engineered to lack a sense of smell, a new study claims. They found super-smeller mice grew even fatter on a high-fat diet, while mice with a diminished sense of smell lost weight.
"For that small group of people, you could wipe out their smell for maybe six months and then let the olfactory neurons grow back, after they've got their metabolic program rewired", Dillin said.
"Acute loss of smell perception after obesity onset not only abrogated further weight gain but also improved fat mass and insulin resistance", stated the researchers.
Potentially good news for humans is that we have less brown fat for our body size than mice do, so it's possible the effect may not apply to us to the same extent, even if the same mechanism is at work. While searching for food, the body stores calories in case it's unsuccessful.
There turned out to be differences in the two types of fat the mice carried: brown fat, which your body burns to generate heat; and white fat, which is stored for energy (and is the kind you pack on when you consume excess calories).
The smell-deficient mice rapidly burned calories by up-regulating their sympathetic nervous system, which is known to increase fat burning.
To test the results, the researchers used mice that had a sharper sense of smell, and followed their weight change.
The research builds on a similar study by Jens Brüning, Director of the Max Planck Institute for Metabolism Research, who created a super-smelling mouse.
Two rodents were fed the same high-fat diet and became obese.
After Professor Dillin's team eliminated the sense of smell in one of those mice, its weight dropped by about a third, to 33 grams.
The mice with no sense of smell appeared to boost the mice's brown fat.
"It's one of the most interesting discoveries to come out of my lab", author Andrew Dillin exclaimed.
The first mouse model was engineered to lose its olfactory sensory neurons, the cells that detect odors and relay the information into the brain, when given a certain drug. The other mouse maintained a weight of around 49 grams.
We all know that smell is an important part of the tasting process, but this is taking it to the next level.