Does Obesity Cause Pain — Or the Other Way Around?

A new study published in the journal Obesity suggests excess weight and physical pain often go hand-in-hand — even if the overweight person is otherwise in good health.

Doctors know chronic conditions like arthritis, depression, fibromyalgia, type 2 diabetes and back pain are more common among the overweight and obese, so they’ve long assumed obesity itself makes people more susceptible to conditions that cause pain.

But in a new Gallup survey of more than 1 million Americans, the relationship between obesity and pain persisted even after researchers tried to account for the influences of other pain-causing health problems.

“Being sick can cause pain, but that doesn’t necessarily take care of the relationship between obesity and pain,” researcher Arthur A. Stone, PhD, distinguished professor and vice chairman of the department of psychiatry at the Stony Brook University Medical Center in Stony Brook, NY, told WebMD.

Compared to normal-weight people in the survey, people in the overweight group — those with BMIs between 25 and 29 — had about 20 percent more pain, and people with BMIs between 30 and 34 had about 68 percent more pain. But those with BMIs between 35 and 39 had 136 percent more pain, and those with BMIs over 40 reported having 254 percent more pain.

That said, relationships between chronic health problems and pain and obesity are complex. For example, arthritis could make some people less active, possibly causing weight gain. At the same time, being overweight strains the joints, leading to joint problems that in turn create pain.

Researchers say that while obesity itself may not directly cause the pain, other studies have shown links between pain and obesity, even when there were no other chronic conditions to explain the findings.

Dr. Stone says more research is needed, but he posits an interesting alternative theory: since fat cells are known to make chemicals that increase inflammation, and inflammation is very closely linked to pain perception, “there’s the possibility that there’s some connection through that kind of process.”