Aside from genetic issues, few things shorten a joint’s shelf life more dramatically than having to carry around too much weight. Data from the first National Health and Nutrition Examination Survey (HANES I) underscored this finding, indicating that obese women have nearly four times the risk of knee osteoarthritis as non-obese women; for obese men, the risk is nearly five times greater. But it’s not just obese people who are at risk. If you’re more than 10 pounds overweight, you’re putting an unhealthy stress on your joints. Keeping your weight down is the single best thing you can do preserve your joints.
It helps to understand the dynamics of how your joints bear weight. Because of the muscles acting across the knee and hip joints, normal walking causes a force across the joints that is equal to approximately four times your body weight. Therefore, if you are, say, 20 pounds overweight, the force across both the knee and hip joints is increased by almost 80 pounds.
Even small amounts of weight loss will decrease this force, slow down the joint’s deterioration and decrease pain. Losing weight reduces the stress on the affected joints, and can mean the difference between needing surgery or not. For a woman of normal height, for every 11 pound weight loss (approximately two BMI units), the risk of knee arthritis drops more than 50 percent!
It sounds almost too simple, but for many of our patients, weight loss is the essential first step in non-operative treatment of arthritis. And maintaining a healthy body weight now is one of the best ways to decrease your chances of developing arthritis down the road.