Weight gain has often been noted as a side effect of quitting smoking, and research has well established that nicotine can function as an appetite suppressant. A new study has now uncovered a novel mechanism showing how nicotine directly activates a protein that signals a type of fat cell to start burning energy.

A few years ago, scientists discovered a new, third type of fat cell called beige fat. This important discovery revealed an entirely new metabolic target for obesity research. Along with brown fat cells, beige fat was found to rapidly burn calories and generate heat.

Now, new research from the University of Michigan Life Sciences Institute has revealed a novel metabolic mechanism explaining how a protein called CHRNA2 specifically stimulates beige fat cells to burn energy. The study found that CHRNA2 receptor proteins are activated by two molecules – nicotine and acetylcholine.

The study found that mice engineered to be unable to make this protein displayed significant weight gain and higher blood glucose levels when fed high-fat diets. As well as potentially explaining how quitting smoking can result in weight gain this research homes in on a metabolic mechanism that could be effectively manipulated to stimulate the burning of calories, kickstarting a person's metabolism.

"Beige fat is very important in regulating whole-body metabolic health," says Jun Wu, one of the researchers on the project. "Our results in mice show that if you lose even one aspect of this regulation – not the whole cell function, but just one part of its function – you will have a compromised response to metabolic challenges."

Previous research following the initial discovery of beige fat has looked into how the body converts the more static, cumulative white fat into a healthier brown or beige fat. Several studies have found ways to help the body in this conversion process, but this new research now suggests a novel pathway for activating the beige fat itself.

The study was published in the journal Nature Medicine.