Understanding the Relationship between Chronic Pain and Obesity

Both chronic pain conditions and obesity are major and increasing public health concerns, and the connections between the two have been firmly established in the medical literature. But as the prevalence of obesity worldwide—and particularly in the United States, where obesity estimates far exceed the world average—continues to grow, a deeper understanding of this connection could potentially benefit both practitioners and patients. A recent large-scale study shows that up to 69% of adults were overweight, with about 35% in the obese category.

A recent review article in The Journal of Pain Research looked at the accumulating evidence strongly suggesting that pain and obesity are “significantly related to each other, and obesity is potentially a marker of greater functional and psychological complications of chronic pain.” The study covered the connection between obesity and chronic pain of many types, including osteoarthritis, migraine, lower-back pain, and even vitamin D deficiency—as well as offering a look at the factors that may contribute to sustained weight loss.

A host of clinical research articles suggest that the conditions are significant comorbidities, adversely impacting each other—along with many other interacting factors.According to the study authors, “Overall, research suggests that obesity makes chronic pain more problematic in general. Obesity is related to greater physical disability and psychological distress in chronic pain patients.Compared to non-obese patients, obese back pain patients appear to be more func­tionally impaired, have greater comorbid problems, and have more radicular symptoms than non-obese counterparts.”

One of the factors leading to increased incidence of chronic pain in obese patients is the heavy weight on joints and the spine. Higher body mass index is associated in arthritis research with greater defective change in knee cartilage and joint space widths. A separate recent study indicated that obese individuals exert significantly greater disk compression force while lifting compared to normal weight individuals, and there are strong links to obesity and degenerative disk disorder. The study also looks at the role of vitamin D in obesity and chronic pain. Low levels of vitamin D appear to be more common in obese people, and poor skeletal mineralization due to vitamin D deficiency may lead to complaints of achiness in the joints and muscles including knee osteoarthritis.

Research suggests that obesity is not only a risk factor for osteoarthritis but also may complicate recovery from joint replacement surgery. Obesity in chronic joint pain may also be related to greater consumption of analgesics; one study noted that obesity was related to daily consumption of analgesics, and obese patients were more likely to be taking strong opioids than normal weight patients.

Among the clinical implications outlines by the review, the authors note that a study of approximately 800 women estimated that the risk of developing knee OA can be reduced by 50% if a person loses as little as 5 kg. Several other studies have shown a direct link between weight loss and joint pain, joint stress, chronic pain, and even migraine pain.

The study authors caution that, “The aforementioned factors are presented as the potential link between obesity and pain. However, some cautionary words need to be in place. None of these factors are likely to explain the entirety of the relationship on their own”