Weight Loss: The Treatment Of Choice For Osteoarthritis?
In recent years, the increasing number of elderly people and the rise of the average body weight have resulted in osteoarthritis (OA) affecting 70% of people over 65 years of age. Being overweight is an important factor in OA. Obese people are at high risk of developing OA especially in the knee.
How Does Obesity Cause Osteoarthritis (OA)?
It is believed that obesity causes OA in two ways:
- Obesity increases the amount of force across the joints. This induces breakdown of the cartilage simply on the basis of excess force, leading to OA. This theory explains why obesity is linked to knee OA more frequently than to hip OA. However, it does not account for the association between obesity and development of OA of the hand—a non-bearing joint.
- People who are overweight possibly have a circulating factor that reaches systemically all joints (hands, hips, knees) causing cartilage breakdown and eventually OA. This explains the relationship between OA and obesity in non-weight-bearing joints, such as the hands and neck.
In support of the second theory comes the recent discovery that the adipose tissue, apart from its role as an energy storage depot, is also a major endocrine organ secreting many active substances whose circulating levels are affected by how obese a person is.
Peptides generated in adipose cells, such as TNF-alpha and leptin, initiate inflammatory processes that account for the low-grade chronic inflammation observed in obese people [1]. It has been postulated that this sustained form of inflammation may exert detrimental effects on the articular cartilage that lead to OA.
Weight Loss: Can It Improve The Symptoms Of OA?
A 2007 review study combined the results of all previous studies that addressed the effect of weight loss on OA [2]. The objective of the study was to assess whether pain and functional disability would change in patients with knee OA after weight loss. The major finding of this meta-analysis was that physical disability of overweight patients with knee OA diminished after a moderate weight reduction regime.
The study concluded that patients should be encouraged to reduce their body weight by 5-10% using a rate of 0.5-1.5 kg/week (1.1-3.3lb/week) to experience a symptomatic relief. Weight loss programs, such as Medifast and Nutrisystem, accompanied by dietary supplements, such as Joint Advance, enable patients to lose an optimum 3lb per week.
To What Extent Will OA Be Prevented If Overweight People Lose Weight?
Data from the Framingham OA study [3] showed that if men in the obesity category (BMI>30) lost enough weight to fall into the overweight category (BMI 26-29.9), and men in the overweight category lost enough weight to move in the normal range (BMI<26) the chances of developing knee OA would decrease by 21.4%. It goes without saying that the drop would be even higher if men in the obesity category lost enough weight to reach the normal reference level.
In the case of women, the rate of knee OA would decrease 33% if their weight dropped from the obesity level to the overweight level or from the overweight level to that of BMI being below 25.
Closing Remarks
To date, it is still far from clear how weight loss, obesity and OA interrelate in the molecular level. We know, however, that being overweight is an important risk factor for OA in the knees, hips and hands, whether it is the result of mechanical stress or secretion of active substances by the adipose tissue. Weight reduction is viewed as an important part of treatment for OA because it increases the function and reduces pain and stiffness. Since obesity and young age correlate with the development of OA in later life, preventive health measures focusing on lowering the incidence of obesity are of most importance.
About The Author
Matthew Denos, PhD, is a researcher with a particular interest in obesity and how it affects the development of diseases of the joints. In his free time, he maintains a blog where he reviews weight loss programs and offers a medifast coupons code, and a nutrisystem discount code.
References
1. TNF-alpha and Obesity. Tzanavari T, Giannogonas P, Karalis KP. Curr Dir Autoimmun. 2010;11:145-156. Epub 2010 Feb 18.
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, Bartels EM, Astrup A, Bliddal H.
3. Felson DT. Weight and osteoarthritis. J Rheumatol 1995; 22(suppl 43):7-9.
