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The possibility of getting chronic daily headaches may be another reason for watching your weight. A new study shows that excess weight may increase the frequency and severity of headaches.

"Obesity is a risk factor for chronic daily headaches," says Marcelo E. Bigal, MD, PhD, a neurologist at the Albert Einstein College of Medicine in New York and a researcher on the study.

"Not only do obese people develop chronic headaches at a higher rate," he says, "but they have more severe headaches, more nausea, and miss more days of school and work than nonobese people."

But there is some good news: Headache medications work just as well for obese people as they do for people of normal weight.

"Yes, obesity is a risk factor, but we can treat these headaches," Bigal tells WebMD.

The study was presented at the annual meeting of the American Academy of Neurology.

Weighing In on Headaches

The study involved more than 30,000 men and women who reported at least one severe headache in the previous year. Based on telephone interviews, the researchers obtained information on the participants' headaches, height, and weight.

Based on their BMI (body mass index -- an indirect measure of body fat), participants were divided into four weight groups: underweight, normal weight, overweight, and obese. Two-thirds of the participants, whose average age was 43, were women.

Among the findings:

--Obese participants were 30 percent more likely to complain of chronic daily headaches, defined as more than 15 headaches that lasted at least four hours per month.

--Chronic daily headaches occurred in 4 percent, 5 percent and 7 percent of the normal, obese, and morbidly obese participants, respectively.

--Thirty-three percent of the obese people missed more than four days of work in one year because of their headaches, compared with 27 percent of both overweight and normal-weight people.

--Obese people were 22 percent more likely to report severe pain more often than those of normal weight.

The duration of headaches did not differ significantly among the groups.

Middle-aged obese women were at highest risk of daily debilitating headaches, says Bigal.

"After three months of treatment, there was no difference in headache frequency or severity between obese people and nonobese people," he says.

'Fascinating' Findings

Christina E. Peterson, MD, medical director of the Oregon Headache Clinic in Milwaukie, Ore., called the findings "fascinating, very fascinating."

About two years ago, other researchers reported a link between obesity and migraine headaches, she says. "This came as a real surprise to the headache community as no one thought obesity was a risk factor," she tells WebMD. "Now this study comes along, confirming the link."

Peterson says many of the older medications used to prevent and treat headache, including Elavil and Depakote, may promote weight gain, while a newer drug, Topamax, may suppress appetite.

"We will now have to factor all this in when thinking about what therapy is best for our patients," she says. "We may have to avoid some of our more standard therapies if we want to avoid that drift toward chronic daily headaches."

The next step, she says, are studies to find out why obesity causes headaches and whether diet and weight loss can prevent or reverse them.

By Charlene Laino, reviewed by Brunilda Nazario, MD

SOURCES: American Academy of Neurology 57th Annual Meeting, Miami Beach, Fla., April 9-16, 2005. Marcelo E. Bigal, MD, PhD, neurologist, Albert Einstein College of Medicine, New York. Christina E. Peterson, MD, medical director, Oregon Headache Clinic, Milwaukie, Ore.