The Impact of Obesity on Arthritis Outcomes

Obesity may affect risk of developing osteoarthritis and rheumatoid arthritis, and it has been linked with increased disease activity and adverse clinical outcomes.

According to the Centers for Disease Control and Prevention, obesity affects more than one-third of Americans, and it has been associated with a range of negative health outcomes, including cardiovascular disease, diabetes, and cancer.1 A large body of evidence has also linked obesity with osteoarthritis (OA) and rheumatoid arthritis (RA), suggesting that it may both influence the pathogenesis of the disease as well as clinical outcomes, disability, and quality of life.

“There is a high degree of interaction between obesity and arthritis, with over 80% of obese patients having some form of joint disease,” according to John Morton, MD, MPH, FACS, chief of bariatric and minimally invasive surgery at Stanford University School of Medicine in California. “Increased weight upon joints, impaired bone and cartilage metabolism, and heightened inflammation associated with obesity are all contributors to this interaction,” he told Rheumatology Advisor.  

Obesity & Osteoarthritis

The relationship between excess weight and OA is well-established. In fact, obesity appears to be the top modifiable factor that influences OA risk, with one study reporting that individuals whose body mass index (BMI) was higher than 30 kg/m2 having a nearly 7-fold increased risk of developing knee OA.2

Two recent meta-analyses found a dose-response relationship between increasing BMI and incidence of both knee and hip OA. Specifically, for each 5-unit increase in BMI, the risk of knee OA increased by 35%, and the risk of hip OA increased by 11%.3,4

“Obesity is a major risk for degenerative arthritis of the lower extremities, especially knees and hips, due to excessive mechanical loading,” Eric L. Matteson, MD, MPH, chair of the Department of Rheumatology at the Mayo Clinic, Rochester, Minnesota, told Rheumatology Advisor. The joints are subjected to force of up to 10 times one’s body weight during physical activity such as walking, and of course, the higher the weight, the greater the joint load will be.

Other findings indicate that obesity greatly increases the odds of needing arthroplasty–and at much younger ages. Findings of a prospective study published in Rheumatology attributed 69% of total knee replacements and 27% of total hip replacements to excess weight and obesity, with further research suggesting that obesity may impede recovery from arthroplasty.2

Obesity & Rheumatoid Arthritis

More recently, attention has turned toward an apparent connection between obesity and rheumatoid arthritis. “There is evidence that obesity is a risk factor for development of RA, and this is more evident in women than men,” said Larry W. Moreland, MD, the Margaret Jane Miller Endowed Professor of Arthritis Research, and chief of the Division of Rheumatology and Clinical Immunology, at the University of Pittsburgh School of Medicine.

“Adipose tissue is an ‘active’ organ in that it [produces] pro-inflammatory molecules such as cytokines, and there are possibly other factors that have not yet been clearly identified as to why obesity has now been identified as a risk factor for developing RA,” he told Rheumatology Advisor.

A significant treatment challenge that remains is the standard dose of RA medications may not attain the same concentrations at sites of inflammation in obese vs non-obese patients, thus rendering them less effective. In recently published data, obese patients with chronic inflammatory rheumatic diseases demonstrate an altered response to disease-modifying antirheumatic drugs (DMARDs) and tumor necrosis factor (TNF) inhibitors.5

“Control of the underlying inflammatory disease is essential to [improving] function and well-being in patients with inflammatory arthritis,” said Dr Matteson. “As well, rheumatologists are part of the patient’s multidisciplinary health team, and must work with other healthcare providers in managing medically-complicated obesity by making appropriate referrals and limiting the use of glucocorticoids which [further] contributes to obesity and its complications.”

Addressing & Supporting Patients’ Weight Loss

The first step for clinicians is to open up the conversation. “Measure each patient’s BMI and start the discussion about treatment,” Dr Morton advises. “There is a continuum of care from counseling to medications to endoscopic intervention to bariatric surgery. You can access these services through accredited centers such as those certified by the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program,” he said.

Research shows that healthcare providers’ support in facilitating weight loss can indeed improve patients’ efforts.6 Equally important, however, is taking a compassionate, non-stigmatizing approach, as studies have also found that clinician empathy increases patients’ motivation to engage in behaviors that lead to weight loss.7 

A website offers several helpful resources for healthcare providers, including tips on starting the conversation about weight as well as information on motivational interviewing and behavioral strategies that can help patients modify their lifestyle habits.

Even slight reductions in body weight can improve pain and mobility in patients with arthritis. “However, it is very difficult for morbidly obese patients to lose significant amounts of weight and maintain their weight loss,” said Stanford Shoor, MD, clinical professor of medicine and rheumatology at Stanford University. “Asking people to lose even 10% of their body mass is difficult both to accomplish and maintain. Setting a goal of 5% over 4 to 6 months allows the opportunity for patients to achieve success and maintenance,” he told Rheumatology Advisor.

In previous research on patients with knee OA, a 5% reduction in body weight led to improvements in joint pain, which is a major barrier to physical activity in such patients, and a 10% weight reduction correlated with moderate-to-large improvements.8

Increasing Activity and Reducing Pain

Exercise programs should be carefully paced and designed to progress gradually. For example, patients with knee OA should start with stationary biking and isometric exercises performed at a low intensity level, and increase the duration of number of exercises very gradually. Pain should be controlled to not only enable more exercise but more daily activity in general.

“Even the best exercise program cannot fully replace the ability to rise from a chair and walk stairs–the common, everyday activities that help to maintain strength in the lower extremities,” and pain can “reduce such ‘maintenance’ activity, further weakening the leg muscles and adding to the cycle of inactivity-pain-inactivity,” Dr Shoor explained.

In addition to pharmacologic pain control options ranging from over-the-counter and topical anti-inflammatory drugs to narcotic analgesics, he suggests that clinicians consider non-traditional strategies such as acupuncture, fish oil, curcumin, glucosamine, and chondroitin, as well as psychological approaches like cognitive behavioral therapy, meditation, relaxation, and hypnosis.

“In some instances, and with the proper eating and exercise habits, bariatric surgery allows morbidly obese patients to ‘jump start’ their weight loss and exercise programs,” added Dr Shoor. In a study reported in 2015 in Arthritis Care & Research, patients with RA who lost a significant amount of weight after bariatric surgery had reductions in disease activity, serum inflammatory markers, and RA-related medication use, with another study finding a reduction in OA symptoms after bariatric surgery.9,10

“Obesity remains a common medical issue, and continued efforts to address its causes and ways to manage it are of highest interest to clinicians,” Dr Moreland stated.

Summary and Clinical Applicability

Obesity may affect risk of developing OA and RA, and it has been linked with increased disease activity and  adverse clinical outcomes. Weight loss and exercise can reduce symptoms and pain, and reducing pain can help increase general activity and exercise.

Related Articles


  1. Adult obesity facts.  US Centers for Disease Control and Prevention website. Accessed October 13, 2016
  2. King LK, March L, Anandacoomarasamy A. Obesity & osteoarthritis. Indian J Med Res. 2013; 138(2): 185–193.
  3. Jiang L, Rong J, Wang Y, Hu F, Bao C, Li X, Zhao Y. The relationship between body mass index and hip osteoarthritis: a systematic review and meta-analysis. Joint Bone Spine. 2011; 78(2):150-5
  4. Jiang L, Tian W, Wang Y, Rong J, Bao C, Liu Y, Zhao Y, Wang C. Body mass index and susceptibility to knee osteoarthritis: a systematic review and meta-analysis. Joint Bone Spine. 2012; 79(3):291-7.
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