How Obesity Affects Osteoarthritis
Learn how carrying excess weight when you have OA increases your risk for other health problems.
Being just 10 pounds overweight puts an extra 30 to 60 pounds of pressure on the knees, making it more likely to develop osteoarthritis (OA) or make the disease worse. Carrying extra bodyweight in OA does more than create a harmful load on joints. Excess fat also acts in non-mechanical ways to speed the destruction of cartilage and joints. Fat is chemically active and constantly releases inflammation-causing proteins and other biochemicals, such as tumor necrosis factor-α and interleukin-1.
Inflammation and OA
Hand OA is about twice as common among obese people as it is in leaner individuals. Being obese also increases the chances that, once you have OA in a joint or joints, you will develop more OA elsewhere. Obese people with OA in one knee, for example, are five times more likely than healthy-weight people to develop OA in the other knee.
Excess fat tissue not only creates a constant state of low-grade inflammation throughout the body, but by placing a mechanical load on cartilage and bone, it “activates” those structures, prompting them to release inflammatory proteins and other factors that cause joint destruction, says van der Kraan.
The Link with Metabolic Syndrome
Some researchers, in fact, call the combination of obesity and metabolic syndrome “metabolic OA,” a distinct and dangerous subtype of OA. When these combine, it is a warning sign that should prompt a close look for heart disease, says Francis Berenbaum, MD, head of the department of rheumatology at the Pierre and Marie Curie University in Paris, France, who is studying age-related joint diseases and metabolism.
“When OA is linked to the metabolic syndrome it aggravates cardiovascular diseases linked to metabolism, such as atherosclerosis, probably through an increase in obesity-related inflammation,” he says. “Additionally, the risk for pain, worsening of OA and the need for [total joint replacement surgery] increase with each component of the metabolic syndrome a patient has.”
Excess Weight is Disabling
Compared with healthy-weight people with OA, Dr. Batsis and his colleagues found that people with OA who were obese needed to take more medications, walked more slowly, were much less likely to be physically active and were at significantly higher risk after six years of developing disabilities that interfere with daily life.
People who were overweight rather than obese in their study had declines compared to those with a normal BMI [body mass index] but less than the group with obesity. This gives doctors reason to encourage lifestyle modification in patients under their guidance so they can safely and effectively lose weight to prevent long-term physical decline and disability risks.
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