Obesity May Increase Physical Pain Reaction

Obesity may heighten physical reaction to pain, according to a new study.

The study shows a greater physical pain reaction in obese people, compared with people who aren’t obese, even after brushing up on their coping skills.

However, subjective pain perception -- how people consciously perceive pain -- wasn’t tied to obesity in the study.

“I think the most important point of this preliminary study is that obese individuals may have a lower threshold for pain [possibly due to chronic inflammation associated with obesity], which is not evident if we rely solely on self-report of pain,” researcher Charles Emery, PhD, tells WebMD in an email.

Emery, a psychology professor at Ohio State University, worked with colleagues on the study. Their findings will be presented in Denver at the American Psychosomatic Society’s annual meeting.

Physical Reaction to Pain

Emery’s team studied 62 people with osteoarthritis, the most common form of arthritis. Participants were 50 to 76 years old. About a third of them were obese.

First, participants got a mild electrical shock to their left ankle to measure their pain reflex. The body automatically pulls away from pain; that automatic physical reaction is the pain reflex.

Obese participants had a stronger pain reflex than those who weren’t obese, the study shows.

Next, participants got a 45-minute lesson in coping skills to help them learn to better handle pain. The lesson included instruction in progressive muscle relaxation.

Then, they took the pain test again. This time, all participants had a milder pain reflex than in the first test. But obese participants still had a stronger physical reaction to pain than those who weren’t obese.

“The relaxation procedure helped both groups cope with pain,” Emery says, in a news release. “Additionally, our tests showed both groups had higher physical pain thresholds after the relaxation session. But the obese participants still had a lower threshold for tolerating the pain.”

Feeling the Pain

After both tests, participants completed questionnaires about pain and anxiety. All had similar perceptions of pain, regardless of obesity.

In other words, obese people had a stronger physical reaction to pain, but their subjective pain perception was the same as people who were not obese.

“This is important because if an obese person begins an exercise program, he may not cognitively experience pain when in fact it is hurting the body on some level,” Emery says, in the news release. “That could lead to severe pain down the road.”

Past studies on obesity have had mixed results. “Some studies say that obese people are more tolerant of pain, while other studies say they are less tolerant,” Emery says.

”Our findings show the importance of looking at objective as well as subjective measurements of how the body responds to pain stimuli,” he adds.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Charles Emery, PhD, psychology professor, Ohio State University. News release, Ohio State University.