We are all aware that excess weight is a risk factor for cardiovascular disease and diabetes, and currently the links between overweight and cancer are beginning to become more widely known. But did you know that carrying excess weight can also prevent your immune system from working properly?
Obesity is known to be associated with a state of chronic systemic inflammation. Fat is an endocrine organ, secreting many factors that immune cells respond to – excess fat is thought to stimulate white blood cells (WBC) that produce inflammatory molecules as a part of the normal immune response upon injury or infection. Fat cells may also produce these inflammatory molecules. Obesity’s effects on the immune system likely underlie some of its connections to chronic diseases.1
Obesity is associated with elevated numbers of circulating immune cells and total WBC,2 as well as elevated activation levels of certain WBC and suppressed immune cell function.3 In short, excess weight seems to promote a state of overstimulation of the immune system, which impairs normal immune function. Calorie restriction, on the other hand improves immune function and reduces production of inflammatory molecules.1
The current study evaluated immune cell number and activation in response to a significant amount of weight loss (average 13.5% of body weight) in type 2 diabetics and prediabetics over a 24-week period. The researchers found an 80% decrease in circulating T-helper cells (a type of immune cell); decreased activation of circulating immune cells and other WBC, and also reduced activation of adipose tissue immune cells.4
This study suggests that weight loss can reverse the damage to the immune system that occurs due to obesity. Weight loss, therefore, in addition to reducing systemic inflammation and risk of chronic disease, may also improve resistance to bacterial and viral infections by restoring balance to the immune system.
Consistent with these data, Dr. Fuhrman has noted that nutritarians often have lower than average white blood cell counts, reflecting appropriate levels of systemic inflammation and immune system activation. Lower WBC counts are reflective of excellent health and associated with longer lifespan.5 As such, those whose healthful eating habits cause WBC counts drop below the normal range should not be alarmed.
1. Dixit VD. Adipose-immune interactions during obesity and caloric restriction: reciprocal mechanisms regulating immunity and health span. J Leukoc Biol. 2008 Oct;84(4):882-92.
2. Womack J, Tien PC, Feldman J, et al. Obesity and immune cell counts in women. Metabolism. 2007 Jul;56(7):998-1004.
3. Nieman DC, Henson DA, Nehlsen-Cannarella SL,et al. Influence of obesity on immune function. J Am Diet Assoc. 1999 Mar;99(3):294-9.
4. Viardot A, Lord RV, Samaras K. The effects of weight loss and gastric banding on the innate and adaptive immune system in type 2 diabetes and prediabetes. JClin Endocrinol Metab. 2010 Jun;95(6):2845-50.
5. Candore G, Colonna-Romano G, Balistreri CR, et al. Biology of longevity: role of the innate immune system. Rejuvenation Res. 2006 Spring;9(1):143-8.
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