People who shed kilogrammes saw only a modest improvement in knee pain, however, researchers from Monash University in Melbourne, Australia, found.
"Preventing weight gain, almost no matter what weight you start out at, is going to be the key to preventing knee problems," said Dr Susan Bartlett, who has studied joint pain and obesity at McGill University in Montreal, Canada, and was not involved in the study.
For the new study, the Australian researchers’ recruited 250 people ages 25 to 60 with no history of knee surgery, injury, or knee joint disease. More than three quarters were women, and many were obese.
Every kilo brings more pain
When the researchers checked in with participants two years after the study began, around a fifth had dropped out. Of the 196 people who remained, more than half had maintained their weight, while 14% had put on weight – 7 kilogram’s, on average – and 30% had lost weight.
For every kilogramme gained, pain scores went up by 1.9 points on a 500-point scale. Stiffness worsened by 1.4 points (on a 200-point scale), and function by 6.1 points (on a 1,700-point scale).
"The changes might be small, but if you can put enough of these changes together, it makes the difference between having symptoms that interfere with life, and keeping them more manageable," Dr Bartlett told Reuters Health.
The link between weight gain and pain was strongest in obese people, who experienced a 59-point increase in pain when they put on weight compared to just 6.4 points in non-obese people.
Weight loss leads to minor improvement
People who shed weight during the study did experience some improvement in knee pain, by 22.4 points on average. Weight loss, however, only led to a small improvement in function of 9.8 points in obese people.
In their report, published in the journal Arthritis Care and Research, Stephanie Tanamas from Monash University and colleagues say previous studies have suggested weight loss can improve knee problems. While their findings bear that out to some extent, a large drop in weight may be needed to see a benefit, the researchers add.
Dr Bartlett did point to one limitation, however. A lot of people, especially those who lost weight, may have lost larger amounts of weight and then regained it, which may have influenced the results.
Still, she said, the study shows there is a lot of value in preventing weight gain in the first place and to some degree in losing extra kilos for people who have knee problems.
(Natasja Sheriff, Reuters Health, June 2012)
Diet and nutrition