FRIDAY, Feb. 10 (HealthDay News) -- There's a clear link between obesity and pain, suggests a new study that finds the heaviest people suffer the greatest discomfort.

Researchers examined data from more than 1 million people who were asked about their health, pain and well-being in telephone surveys conducted between 2008 and 2010. Thirty-eight percent of the participants were overweight and 25 percent were obese. Those who were obese were classified into one of three obesity levels as defined by the World Health Organization.

Compared to people with low to normal weight, pain rates were 20 percent higher for overweight people, 68 percent higher for those in the Obese 1 group, 136 percent higher for the Obese 2 group, and 254 percent higher for the Obese 3 group.

The researchers also found that as people age, excess weight is associated with even higher levels of pain.

The study was published recently in the online edition of the journal Obesity.

"Our findings confirm and extend earlier studies about the link between obesity and pain. These findings hold true after we accounted for several common pain conditions and across gender and age," Arthur Stone, vice chair of the department of psychiatry and behavioral science at Stony Brook University School of Medicine, said in a university news release.

"We wanted to explore this relationship further by checking to see if it was due to painful diseases that cause reduced activity, which in turn causes increased weight," Joan Broderick, an associate professor in Stony Brook's Department of Psychiatry and Behavioral Science and School of Public Health, said in the news release.

"We found that 'pain yesterday' was definitely more common among people with diseases that cause bodily pain. Even so, when we controlled for these specific diseases, the weight-pain relationship held up. This finding suggests that obesity alone may cause pain, aside from the presence of painful diseases," she said.

Musculoskeletal pain was the source of some of the pain, according to the report, but it wasn't the only cause.

Researchers say there are other possible explanations why many obese people suffer from pain, including that the excess fat may trigger processes that result in inflammation and pain. Depression is another possibility.

More research into the pain-obesity connection is needed, they said.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about pain.