It’s no secret that being overweight or obese is a significant risk factor for a wide variety of health conditions. By one estimate, the treatment of obesity and the medical problems associated with it costs $168 billion each year in the US alone. And while many of these diseases have familiar names—Type 2 diabetes, heart disease, cancer, high blood pressure, high cholesterol and metabolic syndrome, to name a few—being overweight or obese can also take a significant toll on the body’s musculoskeletal system.
Based on the body of research available today, it’s useful to talk about three different ways that being overweight or obese may also contribute to chronic musculoskeletal Pain (CMP).
A Simple Matter of Wear and Tear
At one level, the problem involves a simple combination of gravity and biomechanics. Additional weight causes additional wear and tear on the body’s muscles and joints. And wear and tear are cumulative over time. This is particularly true of the knees, hips, and back. For instance:
- Osteoarthritis has grown increasingly common as the rate of obesity has increased. The American Obesity Association warns that individuals with a body mass index (BMI) higher than 25 are at greater risk of osteoarthritis. Obese women are nine times more likely to suffer from osteoarthritis of the knee, often leading to the need for a total joint replacement. However, researchers have found that losing as little as 11 pounds can reduce the risk of knee osteoarthritis by half.
- Excess weight, particularly around the stomach, pulls the pelvis forward and causes an excess curvature in the vertebrae of the lower back, causing pain and stress on the muscles and supporting structures of the back.
- Being overweight or obese may lead to bulging or herniated discs, which may, in turn, contribute to the development of nerve compression, sciatica or piriformis syndrome.
The Downward Spiral of Inactivity
It’s pretty clear that inactivity can contribute to someone becoming overweight or obese. But it’s more complicated than that because physical Inactivity is both a cause and effect when it comes to obesity. Carrying all that extra weight places a great deal of extra strain on the musculoskeletal system as well as the circulatory and respiratory systems. For those who are overweight, even short periods of exercise often cause pain, fatigue, lightheadedness and shortness of breath. They also face a higher likelihood of injury. It’s hardly surprising that these factors would discourage overweight and obese people from being physically active.
This downward spiral may help explain some dismal statistics produced by the University of Alabama’s Nutrition Obesity Research Center and published in the December 2013 Mayo Clinic Proceedings. The average obese man in the US gets just 3.6 hours of vigorous exercise per year, while the average obese woman gets the equivalent of only 1 hour.
Physical inactivity can indirectly lead to CMP, especially in the back, where inactivity is often a major contributing factor and a lack of exercise leaves core muscles stiff, weak and out of condition.
Increased Pain Sensitivity
A link between obesity and pain sensitivity has not been conclusively proven, but researchers have noticed some clues that suggest a relationship. In one recent study, overweight participants—those with BMIs between 25 and 29—reported about 20% more pain than normal-weight participants. At the same time, participants with BMIs between 30 and 34 had about 68% more pain. Participants with BMIs between 35 and 39 had 136% more pain and those with BMIs over 40 reported having 254% more pain.
However, the data are noisy, and it is difficult to control for the fact that excess weight contributes to other health problems that may actually be the cause of participants’ pain. When researchers accounted for the influences of these other health problems and pain-causing conditions, being overweight was no longer associated with being in pain. But participants who were obese still reported more pain than those with normal BMIs.
All this said, fat cells are known to produce chemicals that increase inflammation, which is very closely linked to pain perception. This means that there could very well be a physiological mechanism that translates additional body weight into additional pain sensitivity.
The Good News
So the bad news is that—for a growing number of people—more weight seems to equal more pain. The good news, though, is that the opposite also seems to be true. Losing weight appears to have an immediate effect on pain. If you suffer from back pain and are more than 10 pounds above your ideal weight, losing that weight may significantly reduce the amount of pain you are experiencing. According to Dr. Andre Panagos, co-director of The Spine Center at New York’s Presbyterian Hospital, “Although research on weight loss and back pain is minimal, in my clinic, every single person who loses a significant amount of weight finds their pain to be significantly improved.”