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Excess Body Weight , Joint Pain, & Arthritis
Belly fat is an engine of joint inflammation.
The most important control you have over your joint pain is controlling your weight.
These are exciting concepts, because they point to an element of control over your joints that is well within your personal reach.
To understand why this is important, we need to look at a couple of shocking statistics about how dramatically weight affects the joints.
- If you are one pound over weight, you increase the force of the load on your knees by about 4,800 pounds for every one mile you walk.
- If you are ten pounds over weight, you increase the force of the load on your knees by about 48,000 pounds for every mile you walk.
This is actually quite astounding. It means that the forces of excess weight just keep adding up. As you add more weight over more time, the demands on your joints just continue to grow. This is a bit like loading the trunk of your car with bags of sand or your pickup truck with a load of rock. Keep piling on the load and the vehicle sinks lower and lower. The shock absorbers and springs that support the car just keep groaning under the added weight. Pile up the loads over time and the shock absorbing supports wear out sooner. We can replace the shocks, springs, and struts. But we cannot easily replace the knee or the hip joint. So our response must be to get rid of the excess weight.
We can also look at this by how weight affects the rate of osteoarthritis. For every 2 units of BMI (BMI=body mass index--about 12 pounds), osteoarthritis of the knee increased by 36 percent. Studies have also shown that, since weight gain gradually increases the stress on joints, the weight you gain the decade before you have OA symptoms, particularly in middle age, plays a big role in determining if you will develop osteoarthritis.
[March, LM, Bagga, H. Epidemiology of osteoarthritis in Australia. Med J Australia 2004;180(5 suppl): S6-S10.]
It is very important to understand this last statement—that being overweight may be one of the key factors the eventually leads you to develop osteoarthritis even if you do not yet have the disorder. This was made clear by researchers in England. They studied people over age 50 from three separate clinics over a period of three years. Those who were overweight at the beginning of the study (and who did not have arthritis at the study’s beginning) were more likely to develop osteoarthritis over the next three years. In other words, being overweight or obese actually predicted who would develop arthritis in just three years time.
This study is important because it suggests that you may be able to prevent osteoarthritis by losing excess weight before you develop arthritis. Looked at it in the negative, if you are overweight and you do not take steps to reduce your body weight, your likelihood of going on to develop osteoarthritis may be much higher.
[Jinks, C, Jordan, K, Croft, P. Disabling knee pain--another consequence of obesity: results from a prospective cohort study. BMC Public Health 2006;6:258.]
Other studies looking at obesity and osteoarthritis have shown that being overweight is linked to the progression of osteoarthritis. This means that excess weight can cause osteoarthritis to continually get worse. As body weight further increases, the progression of osteoarthritis accelerates, especially osteoarthritis of the knee.
[Reijman, M, Pols, HA, Bergink, AP, et al. Body mass index associated with onset and progression of osteoarthritis of the knee but not of the hip: the Rotterdam Study. Ann Rheum Dis. 2007;66(2):158-62.]
Women are at particular risk for developing osteoarthritis. Doctors at Oxford University studied 111 women between the ages of 36 to 40 and ages 50 to 55. After factoring out many possible risk factors, body mass index (BMI) was the strongest influence on who developed osteoarthritis. Those between the ages of 36 and 40 who had a BMI greater than 25 (those who were overweight) had a higher risk to developing osteoarthritis. One of the key findings, according to the authors, was that “being overweight before the age of 40 considerably increased the risk of subsequent symptomatic osteoarthritis in women.”
[Dawson, J, Juszczak, E, Thorogood, M, et al. An investigation of risk factors for symptomatic osteoarthritis of the knee in women using a life course approach. J Epidemiol Community Health 2003;57(10):823-30.]
These are all very important ideas to understand. It suggests that the joint pain you have right now, today, could be modified by reducing your body weight. That is a tremendous amount of control. It also suggests that if you are overweight today, but you don’t have joint pain right now, you could gain control over whether you develop osteoarthritis.
Obesity and Risk for Knee or Hip Replacement
Several studies have shown that being overweight or obese may also preduct whether or not you will eventually need to have knee replacement surgery. I is important to know that this also applies to joint replacement in younger people. This implies that osteoarthrisis is not a disease of aging, by may be, in part, a disease of lifestyle or of premature aging. Looked at another way, it may be a disease of inflammation and of excessive joint stress, which can occur even when you are younger.
[Harms, S, Larson, R, Sahmoun, AE, Beal, JR. Obesity increases the likelihood of total joint replacement surgery among younger adults. Int Orthop. 2007;31(1):23-6.]
Beyond osteoarthritis of the knee, there is now also evidence that being overweight can increase the risk of needing a hip replacement as well.
To summarize, studies have shown the following with regard to excess body weight and joint inflammation:
1) Excess body weight increases the risk of developing OA if you don’t already have OA
2) Excess body weight increases the speed of progression of OA if you already have OA
3) Excess body weight is linked to a greater risk of OA even in young people
4) Excess body weight increases the likelihood of having knee replacement surgery in old age
5) Excess body weight increases the likelihood of having knee replacement surgery even in young people
6) Being overweight before age 40 increases the risk of developing OA in the future
The effect of excess weight bearing down on joints is important, but it is not the only effect of excess weight. It is now clear that belly fat secretes a vast array of inflammatory molecules, which have tremendous joint-damaging potential. This is another reason Excess weight has another dramatic effect on joints, which get very little attention. This has to do with joint-damaging substances that are produced by fat cells.
See Belly Fat Fuels Joint Inflammation
[Manek, NJ, Hart, D, Spector, TD, MacGregor, AJ. The association of body mass index and osteoarthritis of the knee joint: an examination of genetic and environmental influences. Arthritis Rheum. 2003 Apr;48(4):1024-9.]
Calculate Your Body Mass Index
Body Mass Index (BMI), which is a number calculated from the ratio between a person's weight and height, provides a reliable indicator of body fatness for most people. It is used to screen for weight categories that may lead to health problems.
If you have a BMI reading of between 18.5 and 24, you are regarded as being of normal body weight. Below 18.5 is underweight.
A BMI reading of between 25 and 29.9 is regarded as being overweight. Between 30 and 34 is regarded as obese.
A reading between 30 and 34 is regarded as obese and over 34 as being very obese.
To use the table, find the appropriate height in the left-hand column labeled Height. Move across to the adjacent given weight (in pounds). The number at the top of the column is the BMI at that height and weight. Pounds have been rounded off.
|Body Weight (pounds)|
BMI greater than 35? Go to Table 2
|Body Mass Index Table 2|
|Body Weight (pounds)|
[Overweight Men At Risk Of Osteoarthritis Of Both Hip And Knee, ScienceDaily, May 29, 2008] —
Men who are overweight or obese are much more likely need a hip replacement for osteoarthritis than men who are of normal weight, finds new research.
People who are overweight are known to be more likely to get osteoarthritis of the knee, but this is the first study to show that being overweight is a risk factor for hip osteoarthritis in men but not women.
Researchers compared the body mass indexes of 1,473 Icelandic people who had undergone hip or knee replacement with those of 1,103 people who had not had joint replacement surgery. All were born between 1910 and 1939.
They found women who were overweight (BMI>25) were no more likely to have had a hip replacement than women of normal weight, but men were. Men who were obese (BMI>30) were 70 per cent more likely to have had hip replacement surgery.
People of both sexes who were overweight were much more likely to have had knee replacement surgery and the more overweight they were the more likely it was. Men who were obese were five times more likely to have had a replacement knee and women four times more likely.
The authors say: “The study supports a positive association between high BMI and total knee replacement in both sexes, but for total hip replacement the association with BMI seems to be weaker, and possibly negligible for women.”Journal reference:
Franklin et al. Sex differences in the association between body mass index and total hip or knee joint replacement due to osteoarthritis. Annals of the Rheumatic Diseases, 2008; DOI: 10.1136/ard.2007.086868