A report in the American Journal of Public Health finds teenagers who smoke heavily were likely to grow up to be overweight.
There's still no evidence cigarettes directly cause obesity. But researchers say the possible connection is something people should consider.
Smoking has long been linked to thinness not obesity.
But in this report 35 percent of the women who'd been heavy smokers ended up being fat around the middle as adults.
Doctors caution more research is needed to confirm the results.