April 6, 2009 -- A new study suggests a link between belly fat and the movement disorder restless legs syndrome, but more research is needed to confirm the association, experts say.
Study participants with the biggest bellies were slightly more than one and a half times more likely to have restless legs syndrome than those with the smallest.
A similar association was seen in participants who were obese, regardless of their belly size, compared to those who were not obese.
Restless legs syndrome (RLS) is a neurological disorder that affects as many as one in 10 American adults.
The causes are poorly understood. About 50% of people treated for RLS have a family history of the disorder, according to the National Institute of Neurological Disorders and Stroke (NINDS), but there is also strong evidence that environmental influences contribute to RLS.
Belly Fat, RLS
In several previous studies, obesity was shown to increase the risk for developing the neurological disorder, but none of the studies was designed for the purpose of examining this link, says Xiang Gao, MD, PhD, of Harvard Medical School and Harvard School of Public Health.
“We designed our study to look specifically at obesity, as measured by body mass index (BMI), and waist circumference,” Gao tells WebMD.
The investigation included 65,554 women and 23,119 men participating in two ongoing, comprehensive health studies -- the Nurses Health Study II and the Health Professionals Follow-Up Study.
The participants were considered to have restless legs syndrome if they met four diagnostic criteria for the disorder recommended by an international study group and if they had symptoms five or more times a month.
A total of 6.4% of the women in the study and 4.1% of the men were considered to have RLS.
The study revealed that:
- Obese participants -- those with a body mass index (BMI) of 30 or more -- were 42% more likely to have the disorder than those who were normal weight or underweight (BMI of less than 23).
- The 20% of the participants with the largest waist circumferences were 1.6 times more likely to have RLS than the 20% with the smallest waists.
- Being overweight or obese early in adulthood and weight gain from early adulthood to middle age was associated with a higher prevalence of restless legs syndrome.
More Study Needed
The findings, published in the April 7 issue of the journal Neurology, suggest a “modest, but significant” link between obesity and RLS, Gao says.
“We need more research to determine if obesity really is a cause of restless legs syndrome,” he says. “Both obesity and RLS are very common in the U.S., and obesity may turn out to be a modifiable risk factor.”
University of Maryland Neurologist William Weiner, MD, agrees that more research is needed to confirm that obesity and waist circumference play a role in RLS.
“This study makes the case that obesity is related in some way to restless legs syndrome, but we certainly can’t say that obesity causes it,” he says. “On the other hand, encouraging people who are obese to lose weight is certainly in their best interest.”