How Fat Affects Osteoarthritis
Osteoarthritis (OA) has always been the most common type of arthritis, but today, rates are higher than ever. They’ve risen right along with increases in obesity, according to Stephen Messier, PhD, who directs the JB Snow Biomechanics Lab at Wake Forest University in Winston-Salem, North Carolina.
“The increase in the prevalence of OA is directly attributable to the rise in obesity,” he says.
Why Fat Matters
Why? Extra pounds are hard on joints. The more you weigh, the more stressed and damaged your joints can become. For example, the knees of healthy-weight people absorb about 1.5 pounds of force with every step. If you add OA to the mix – with the joint misalignment that often goes with it – your knees take even more of a beating. When you go up and down stairs or squat to pick something up, the pressure increases exponentially. You can see why a lifetime of movement can take a toll.
Yet if joint stress is the only cause of arthritis, then why is hand and finger arthritis so common?
“Obviously, you don’t walk on your hands, so there must be something that causes the joint to break down more rapidly than it might otherwise,” says David Felson, MD, a professor at Boston University School of Medicine.
That “something” is a group of inflammatory chemicals called adipokines that fat cells produce and release into your body. In short, fat creates inflammation in your joints in addition to the excess stress it puts on them. For people with OA, obesity is a one-two punch.
OA gets worse faster and is more severe in people who are obese than in those who weigh less. Studies have also shown that people who are overweight or obese are more likely to need a hip or knee replacement. They also tend to have more complications and poorer outcomes after the surgery.
In a 2018 study, researchers at NYU Langone Health in New York City reported more complications in obese patients than in average-weight patients undergoing total joint replacement. They also found the complication rate increased as weight went up. The goal, the researchers say, is to reduce weight and inflammation before deciding on surgery. In some studies, people who dropped a lot of weight after bariatric surgery decided they didn’t need a hip or knee replacement after all.
Other Health Problems
People with OA are more likely to have additional health problems (doctors call them comorbidities) including diabetes, high blood pressure and depression. According to the CDC, nearly half the people with arthritis have heart disease, too.
The same fat-related inflammatory proteins that contribute to OA are involved in all these disorders. Exercise is among the best ways to prevent heart and blood sugar problems, but many people with OA, especially if they’re obese, struggle to get enough physical activity. The combination of inflammation and lack of exercise creates a cycle of weight gain, disability and poor health.
Why Weight Loss Matters
The good news is that most or all of these problems can be remedied by dropping a few pounds. Losing just 10 percent of your body weight can cut arthritis pain in half. Losing 20 percent can cut arthritis pain by another 25 percent or more, Dr. Messier says. It may also slow or even stop disease progression. The bonus: Healthy weight loss can also lower blood pressure and reduce the risk of diabetes and heart disease.
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