While it is known that osteoarthritis is the most common type of arthritis and that prevalence increases with age, it's important to recognize what might be modifiable risk factors for osteoarthritis. One such risk factor is being overweight.
Overweight Is Risk Factor for Knee Osteoarthritis
Overweight people are at high risk for developing osteoarthritis, especially knee osteoarthritis. As a matter of fact, studies have consistently shown that overweight women have 4 times the risk and overweight men have 5 times the risk of developing knee osteoarthritis when compared to people who are normal body weight.
Overweight Also Increases Risk of Hip Osteoarthritis
Overweight people also have a higher risk of developing hip osteoarthritis, though the correlation is not as strong as it is with knee osteoarthritis. For example, it has been estimated that the force of 3 to 6 times a person's body weight is exerted across the knee while walking. In other words, being 10 pounds overweight increases the force on the knee by 30 to 60 pounds with each step taken while walking. The force across the hip is, at most, 3 times body weight. Other factors are likely contributing to the risk of hip osteoarthritis that are more significant than being overweight.
The Association Between Overweight and Hand Osteoarthritis
Unexpectedly, studies have also shown an association between being overweight and the risk of developing hand osteoarthritis. While it is obvious that being overweight increases the stress load across the knees or hips, possibly hastening the breakdown of cartilage, a systemic factor (pertaining to the whole body or a specific body system) may also be involved.
The Benefits of Weight Loss
Can we assume then that weight loss would dramatically reduce the risk of osteoarthritis? According to data derived from the Framingham Osteoarthritis Study, if obese men (Body Mass Index 30 or higher) lost enough weight to fall into the overweight category (BMI 26-29.9) and men in the overweight category lost enough weight to fall into the normal range (BMI less than 26), the rate of knee osteoarthritis would decrease by 21.4%. Similarly for women, if obese women (BMI 29 or higher) dropped into the overweight category (BMI 25-28.9) and women in overweight category dropped into the normal range (BMI less than 25), the rate of knee osteoarthritis would decrease by 33%.
Overweight osteoarthritis patients who lose weight experience relief from osteoarthritis symptoms, such as pain and stiffness. The amount of weight loss needed to completely alleviate symptoms and prevent disease progression is not known.
Are Doctors Recommending Weight Loss?
Since overweight is tied to the risk of developing osteoarthritis and weight loss is connected to symptom relief and improved function -- are doctors recommending weight loss and weight control to their patients? A telephone survey conducted by the Centers for Disease Control and Prevention (CDC) in 2005 revealed that of more than 31,000 overweight or obese people with arthritis who could have been advised by their doctor to lose weight, only about 45% were advised by a doctor or health professional that losing weight may help their symptoms. The researchers determined that arthritis patients who were advised to lose weight were 4 times more likely to try than patients who were not advised to lose weight.
If you are overweight, bring up the subject of weight loss with your doctor, especially if your doctor hasn't already started the conversation. Eat a healthy diet, improve your level of physical activity, and find the motivation you need to make necessary changes.
Weight and Osteoarthritis. David T. Felson. American Journal of Clinical Nutrition. March 1996. Are Doctors Advising Their Overweight Patients to Lose Weight? Arthritis Foundation Research Update. May 2007. Osteoarthritis and Weight Management. Susan Bartlett, PhD. Johns Hopkins Arthritis Center. Accessed 1/29/2008.
Weight and Osteoarthritis. David T. Felson. American Journal of Clinical Nutrition. March 1996.
Are Doctors Advising Their Overweight Patients to Lose Weight? Arthritis Foundation Research Update. May 2007.
Osteoarthritis and Weight Management. Susan Bartlett, PhD. Johns Hopkins Arthritis Center. Accessed 1/29/2008.