Past studies have found that heavier people, especially women, are
more likely to develop osteoarthritis and often have more severe
This study goes a step further. It suggests that people with a
higher body mass index (BMI), a measure of weight in relation to
height, may have more pain than normal-weight people with the same
amount of arthritis-related damage.
“My main innovation here was that I wanted to link up BMI, OA
severity and pain to try to see what causes the pain,” Elizabeth
Weiss told Reuters Health.
Weiss, an anthropologist at San Jose State University in California,
studies the bones of past populations. She said that no matter where
and when populations existed, osteoarthritis seems to be as common
among those long gone as it is today.
Osteoarthritis occurs when the protective cartilage around joints -
such as in the hands, neck, knees and hips - starts to wear down.
When this happens, the bones begin to rub together, which can make
walking and other everyday activities painful.
According to the Centers for Disease Control and Prevention, about
14 percent of adults in the U.S over age 25 have some form of
Weiss studied modern people because she wanted to know whether knee
arthritis would have caused similar amounts of pain among past
peoples who were less likely to be overweight or obese, compared to
"I figured that if the data showed that BMI was the real culprit of
pain in knee OA patients, then past people would not have felt much
pain, and for (doctors) it would mean that decreasing BMI would help
patients feel better even if their OA was not improved,” she said.
Weiss studied the health records of almost 5,000 people between 45
and 79 years old who were part of the four-year National Institutes
of Health Osteoarthritis Initiative study.
Of the participants, 1,390 had already been diagnosed with knee
osteoarthritis, 3,284 did not have the disease but were at risk of
developing it and 122 did not have osteoarthritis or related risk
Weiss analyzed X-rays to determine the severity of patients’
arthritis and used the health records to gather information on their
BMI and pain levels during everyday activities.
She found that patients with a higher BMI reported more pain, even
after taking into account the severity of their joint damage.
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For each category of arthritis severity, pain scores were
substantially higher among obese patients than among normal-weight
patients. Scores for overweight patients fell somewhere in the
Excess weight can intensify the amount of stress on the
weight-bearing joints of the knees, and without a normal amount of
protective cartilage, moving around gets more and more painful,
Weiss said in her report. Certain hormones associated with obesity
may also play a role in the severity of both knee arthritis and
Even though osteoarthritis is a progressive disease and its effects
are irreversible, losing weight should help reduce pain related to
the condition, Weiss writes in the journal Rheumatology.
She said weight loss might be the best medicine for people with
osteoarthritis and doctors should consider suggesting the strategy
as opposed to more drastic treatments such as surgery. Other common
arthritis treatments include physical therapy as well as pain
relievers and anti-inflammatory medications.
Losing weight could jumpstart a healthy cycle, Weiss said: a
decrease in body weight could lessen pain, which in turn might make
people more likely to take on more physical activity, resulting in
even more weight loss.
It might be difficult for a person who is already experiencing a
high level of pain to become active in order to lose weight,
however. Weiss suggested trying to lose the weight before starting
“It is easier to lose weight through dietary changes than through
exercise. Small changes can sometimes make big differences,” she
said. “For example, drinking water rather than cola or finding ways
to increase activity that will become a habit, like parking further
from the store entrance or taking stairs instead of an elevator.”
Rheumatology, online June 17, 2014.
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