In the study, which was supported by a grant from the National Institutes of Health and the National Institute of Neurological Disorders and Stroke, none of the participants had diabetes, arthritis or were pregnant.
Of the groups, 6.4 percent of the women and 4.1 percent of the men were identified as having RLS.
Kathy Page has suffered from RLS most of her life. Though medication controls some of the symptoms, at their worst, she has a "complete inability" to lie still and relax.
"Imagine an itch on the bottom of your foot when you have socks and tightly tied shoes," said the 53-year-old. "You just can't get them off fast enough to get to the itch. Now imagine that magnified 50 times and you sort of get the idea."
Page, who lives on a farm and works as a purchasing agent for an electric cooperative, said she finds the Harvard study "interesting." She is not a diabetic or taking anti-depressives.
"I have never connected it with my weight gain, but the fact is I have gained a lot of weight," she told ABCNews.com. "I have not studied this information completely but it certainly does make one wonder if there is a connection. Obesity can cause many problems that we know."
One of the challenges related to RLS is many do not understand the disorder.
Doctors can sometimes confuse RLS with other neurological conditions like peripheral neuropathy or nocturnal cramps, according to Alon Avidan, director of the Sleep Center at the University of California Los Angeles.
In children, it can be mistaken for Attention Deficit Hyperactivity Disorder.
"Some [doctors] are not aware of the disease and some have never heard of it," Avidan told ABCNews.com. "Mainly it's lack of education how to treat it and many confuse it with other disorders. People are also afraid to commit patients to treatments that may involve long-term therapy and are not aware the drugs are quite effective."
Doctors prescribe dopamine agonists like Requip or Mirapex, which can have side effects, like daytime sleepiness, nausea and drop in blood pressure. Some patients also experience "rebound" effects, making the symptoms worse.
Avidan said the obesity connection was "new to me," although he acknowledged the importance of dopamine in RLS.
"It's not well understood why an area of the brain stops manufacturing dopamine," he said.
While some studies show embryonic cells can promote dopamine function in the brain, those therapies are not yet available to the public, according to Avidan.
"Right now the best therapy is to give chemicals they are missing," he said. "But it's not the entire puzzle."
Scientists say more research is needed to confirm whether obesity causes RLS and whether keeping a low BMI score and small waist size could help prevent the disorder.
But the study has "potential significance," according to Dr. John Winkelman, who sits on the board of the RLS Foundation and is medical director of the Sleep Health Center of Brigham and Women's Hospital in Boston.
"We already know RLS is associated with a variety of other bad outcomes," he told ABCNews.com. "Sleep disturbances increase the risk of anxiety and mood disorders."
Winkelman has published a paper on a similar association between RLS and cardiovascular disease. "But we need more longitudinal studies to help determine which way the arrow points," he said.