Strolling to the bus stop, fidgeting during a meeting, standing up to stretch, jumping off the couch to change channels and other seemingly minor physical activity can make the difference between being lean and obese, researchers reported Thursday.

The most detailed study ever conducted of mundane bodily movements found that obese people tend to be much less fidgety than lean people and spend at least two hours more each day just sitting still. The extra motion by lean people is enough to burn about 350 extra calories a day, which could add up to 10 to 20 pounds a year, the researchers found.

“There are these absolutely staggering differences between people who are lean and people who are obese,” said James Levine of the Mayo Clinic, who led the research being published in today’s issue of the journal Science. “The amount of this low-grade activity is so substantial that it could, in and of itself, could account for obesity quite easily.”

Perhaps more importantly, Levine and his colleagues also discovered that people appear to be born with a propensity to be either fidgety or listless, indicating that it will take special measures to convert the naturally sedentary into the restless.

“Some may say this is a story of doom and gloom — that people with obesity have no choice. It’s all over. I would argue exactly the opposite,” Levine said. “There’s a massive beacon of hope here. But it’s going to take a massive, top-down approach to change the environment in which we live to get us up and be lean again.”

Other researchers agreed, saying the new study, while small, provides powerful new evidence that a major cause of the obesity epidemic is the pattern of desk jobs, carpools, suburban sprawl and other environmental and lifestyle factors that discourage physical activity. And despite generations of parents’ admonitions to the contrary, people should be encouraged to fidget.

The researchers determined that each day, the lean subjects spent at least 150 more minutes moving in some way.

“If the obese people were to adopt the same activities, they have the potential to burn an extra 350 calories a day,” Levine said. “It’s huge.”