Nicotine’s Effect on Brain Cells Found to Explain Why Smokers Gain Weight When They Quit Smoking

A new animal study helps explain why many smokers gain weight when they quit smoking. The answer lies in nicotine’s effect on brain cells that usually tells a person to stop eating once they feel full.

A person who quits smoking gains an average of 10 pounds, the Associated Press reports.

Nicotine latches onto a number of receptors on the surface of brain cells, leading to addiction. In a study of mice, Yale University researchers found that both nicotine and a related drug called cystine activated a different receptor in the brain, than the one that triggers addiction. This receptor is in a region of the brain that regulates appetite. Lead researcher Marina Picciotto reports in Science that nicotine binds to this receptor, which then sends a signal to the rest of the brain that leads to a feeling of fullness, similar to the signal the brain sends after eating a large meal.

Mice that received a drug binding to this receptor ate half the amount of food as mice who didn’t receive the drug in the two hours after they received the drug. Their body fat decreased by 15 to 20 percent over 30 days.

In a news release, Picciotto said the findings might one day lead to a new treatment to suppress appetite during the beginning stages of smoking cessation.