An estimated 12 million Americans -- including half a million children -- are affected by the disorder, which causes a "creeping, itching, pulling, creepy-crawly, tugging, or gnawing" sensation in the limbs, according to the Restless Legs Foundation.
"My legs felt like they were being shocked and they would practically move on their own," said Kathy Page of Sedalia, Mo., who suffers from the condition.
"It is hard to explain the immense need to move your legs," she told ABCNews.com. "It's a feeling that if you don't move them and move them now you will just go insane."
"It's a very real condition," said Georgianna Bell, RLS Foundation executive director. "It's something you must have a prescription for -- not just something you pick up over the counter."
Researchers at Harvard University School of Public Health took surveys of 88,000 men and women and found that those who were generally obese -- with a body mass index higher than 30 -- were at 40 percent higher risk of developing restless legs syndrome.
But those with a high waist circumference had an even higher risk -- 60 percent, according to the study that was published in the April issue of "Neurology," the medical journal of the American Academy of Neurology.
Scientists think that the levels of dopamine -- which control both movement and the pleasurable feeling from eating -- may be involved.
Restless legs syndrome affects about 5 percent to 10 percent of the general population, affecting sufferers' work, relationships and health. At its worst, the syndrome can cause anxiety and depression, according to sleep experts.
Often symptoms are worse at night or when resting and resolve upon moving. RLS can also cause difficulties falling or staying asleep. Many also have periodic leg movements -- jerks that occur every 20 or 30 seconds throughout the night.
According to the Harvard study, the higher risks seem to lie in lower levels of dopamine, the chemical in the brain that transmits signals between nerve cells and controls movement.
Though scientists don't exactly know why, lower dopamine levels are associated with Parkinson's disease, as well as restless legs syndrome.
Dr. Xiang Gao, one of the co-authors of the study, says some studies suggest that obese people have lower dopamine receptor levels in the brain.
"Since decreased dopamine function is believed to play a critical role in RLS as well, this could be the link between the two," said Gao, a research associate at the department of nutrition at Harvard School of Public Health.
The study points to a "significant risk" for those who are obese, Gao told ABCNews.com, "especially with the high prevalence of obesity."
"Forty percent is significant for public health because right now 30 percent of all Americans are obese," he said.
Gao said doctors might consider weight reduction programs for patients who suffer from restless legs syndrome, though the study points out an association between the two, rather than a cause and effect.
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.