Smoking cigarettes, even with its health risks, has long been used as a way to shed pounds. Now scientists have discovered how the habit suppresses appetite, pointing the way for potential weight-loss drugs.
Nicotine, the addictive substance in cigarettes, quells appetite by latching to certain brain receptors that crank up the activity of a system of neurons influencing food desire, according to a study in the journal
Science. Scientists identified this pathway as the hypothalamic melanocortin system.
In experiments with mice, the researchers determined which nerves in the brain are affected by nicotine, suggesting a pathway for weight-loss drugs, said Marina Picciotto, the study’s lead author and professor of psychiatry at Yale University in New Haven, Connecticut. Drugs might be developed that mimic the effects of nicotine on the brain’s appetite system, now that researchers know where to aim, she said.
“Whether it works for weight gain in humans hasn’t been studied,” Picciotto said in a telephone interview. “It does work in mice.”
One of the substances she used in the mice to stimulate weight-loss, cytisine, is used as a smoking-cessation drug in Eastern Europe, she said.
Nicotine seems to have a long-term effect on weight-loss, with smokers keeping off the pounds they lost when they started until they quit, Picciotto said. Smokers have a “notably lower” body mass index than non-smokers and generally gain about 5.5 pounds (2.5 kg) when they quit, according to the report.
Smoking to Stay Lean
“You know what’s worrying?” Picciotto said. “In surveys, the number one reason teenage girls start smoking is to stay lean.”
Smoking is the leading cause of preventable death in the developed world and kills 443,000 and sickens 8.6 million each year in the U.S., according to the Centers for Disease Control and Prevention.
About 68 percent of American adults are overweight or obese, raising their risk of diabetes, heart disease, high blood pressure and cancer, according to a 2008 National Health and Nutrition Examination Survey. Almost 34 percent are obese.