In our era of baby boomers and Western diet, the population’s average age and body weight—two key biological determinants of musculoskeletal health—continue their upward trend. Today, almost 3 out for 4 people over 65 suffer from osteoarthritis (OA). Along with age, obesity is the primary risk factor for developing OA. Affliction of both knee joints is the type of OA most commonly found in overweight people.
How Does Being Overweight Affect Your Joints?
Overweight and obesity affect your joints in two ways.
1. Mechanical force upon a joint
Because excess weight exerts unnatural pressure upon the knee joints, the cartilage is damaged and OA ensues. Mechanical force is most severe upon the knees and to a lesser extent, upon the hips.
2. Circulatory factors
Hand joints are not subjected to excess pressure from being overweight and yet, according to studies , obese persons are at increased risk for the development of osteoarthritis of the hand. This would imply a systemic factor that affects all joints regardless of the mechanical force they are subject to. Scientists have zeroed in on adipose (fatty) tissue as the culprit.
Adipose cells secrete pro-inflammatory cytokines, such as the peptide TNF-alpha (tumor necrosis factor.) As part of its job in regulating immune cells, this substance initiates systemic inflammation. Elevated levels of the peptide may account for the chronic inflammation that plagues obese individuals. It is believed that sustained systemic inflammation may have a degrading effect on articular cartilage, which results in OA of non-weight-bearing joints.
Can Weight Reduction Alleviate OA Symptoms?
A meta-analysis of prior OA studies was conducted in Denmark in 2007 . The aim of the review study was to determine whether weight reduction of overweight patients would result in pain relief and improved functionality. The data collected from previous RCT’s (randomized controlled trials) was analyzed extensively. The resultant finding was that a standard weight reduction regimen translated into improved functionality and pain relief for overweight people suffering from OA.
A 10% reduction in total body weight is the goal that obesity specialists recommend for obese and overweight patients. However, the meta-analysis study discovered that relief from symptoms begins with as little as a 5% reduction of excess weight.
To help achieve those targets, an effective weight loss program such as Nutrisystem and Medifast may be required, as demonstrated by The Parker Institute study conducted in Denmark . Christensen and his group assessed the effect of weight loss, by means of a low energy diet, on the function of obese, knee OA patients. They evaluated the symptoms of OA before and after weight loss, as reported by the patients using a questionnaire that addressed the severity of joint pain, stiffness and limitation of physical function. The investigators noticed that there was a 10% improvement in perceived OA symptoms for each percent of body fat reduced!
Can Weight Reduction Prevent The Onset of OA?
This question was answered by the Framingham study. Health information was collected from 1420 subjects for several decades in Framingham, England. Data was analyzed to understand how weight loss might prevent OA.
For men and women, obesity is a condition that is defined as having a body mass index (BMI) of greater than 30; overweight is defined as a BMI between 26 and 29.9; and normal weight is defined as a BMI under 26. Using these standard definitions, researchers published these findings:
When obese men lost enough weight to move into the overweight category; and when overweight men lost enough weight to move into the normal category; then the chances of the study subjects developing knee OA were reduced by 21.4%. If obese men lost sufficient weight to become part of the normal weight category, then the reduction of knee OA would be much greater.
For women following a parallel trajectory of weight reduction, the prevention of knee OA was even more significant: 33%.
The study also showed that being obese early in life increases the risk of developing OA in later life.
While it is readily apparent how mechanical stress caused by excess weight destroys cartilage resulting in knee and hip OA, scientists are now investigating how circulatory factors produced by adipose tissue, can result in deterioration of non-weight-bearing joints.
Unlike other causes of OA, obesity is a modifiable risk factor. For young people, it is important to maintain normal weight levels in order to avoid OA later in life. Apart from invasive arthroplasty – the surgical replacement of the joint – weight loss has been found to be the single most effective method for alleviating the suffering caused by osteoarthritis in obese individuals.
About The Author
With a keen interest in obesity and related diseases, such as OA, Dick French, PhD, writes articles based on recent peer-reviewed publications. He presents information about popular weight loss programs in his blog, where he also offers a BistroMD coupon and a savings coupon for Nutrisystem diet, two proven weight management programs.
1. Hand osteoarthritis in Chuvashian population: prevalence and determinants. Kalichman L, Kobyliansky E. Rheumatol Int. 2009 Apr 9.
2. Ann Rheum Dis. 2007 Apr;66(4):433-9. Epub 2007 Jan 4. Effect of weight reduction in obese patients diagnosed with knee osteoarthritis: a systematic review and meta-analysis. Christensen R, et al.
3. Weight loss: the treatment of choice for knee osteoarthritis? A randomized trial. Christensen R, Astrup A, Bliddal H. Osteoarthritis Cartilage. 2005 Jan;13(1):20-7.