Shedding pounds—through diet, exercise, or surgery—consistently lowers CRP, regardless of the type of weight-loss intervention, a new review study suggests Writing in the January 8, 2006 issue of the Archives of Internal Medicine, Dr Elizabeth Selvin (Johns Hopkins University, Baltimore, MD) and colleagues report that for every 1 kg of weight loss, CRP levels dip by 0.13 mg/L.
"Our results suggest that weight loss may be an effective nonpharmacologic strategy for lowering CRP level," Selvin et al write. In an interview, Selvin elaborated: "We’ve known for a long time that CRP is related to measures of adiposity, mostly in cross-sectional studies related to BMI and weight. There have been many small studies looking at weight loss and changes in CRP, and so this study really summarizes all of the literature on those weight-loss trials."
To examine the impact on CRP across weight-loss interventions, Selvin et al identified, through a literature search, a total of 33 studies examining one or more interventions: 28 lifestyle interventions and five surgical interventions. When all interventions were combined, weight loss was associated with a decline in CRP—approximately 0.13 mg/L for every kilogram of weight loss.
Analyzed separately, both lifestyle interventions and surgical interventions produced reductions in weight and CRP level, although the magnitude of the losses was greater with surgery. Only two small liposuction studies were available for analysis—previous studies have suggested that since liposuction does not induce the same metabolic changes as exercise or diet, it may not have the same effects on CRP. In Selvin et al’s analysis, however, weight loss through liposuction was also associated with reductions in CRP levels, although, due to small sample sizes, these were not.
Intervention Mean weight change (kg) Mean CRP change (mg/L)
Diet or exercise -6.2 -0.9
Surgery -33.1 -4.5
"Our study shows that regardless of the type of weight-loss intervention, weight loss is associated with a decline in CRP." "If you lose weight, CRP levels go down."
The mechanisms linking weight loss and CRP, as well as the implications of this relationship, are still up for debate, she added.
"We know that fat cells look like they are directly involved in the production of inflammatory markers, and so the fat cells themselves induce CRP production," Selvin explained. "It’s been suggested that inflammation itself might represent one of the causal intermediates between weight and heart-disease risk, and so it’s the increased amount of adipose tissue that results in increased levels of inflammation that’s then resulting in increased heart-disease risk. So the converse is that if you induce weight loss, that decreases inflammation in the body, which could result in a decreased heart-disease risk. That’s the hypothesis, but it’s very much up for debate."
Also controversial is the role of using CRP as a screening test, she acknowledged.
Selvin believes her study findings are important from a research perspective and not necessarily for clinical practice. "In clinical practice, the debate is really whether to screen or not to screen, which really is a separate issue, and this paper does not inform that debate very much except to the extent that it really shows if you want to get CRP levels down, then weight loss is a very effective nonpharmacologic strategy."
Selvin E, Paynter NP, Erlinger TP. The effect of weight loss on C-reactive protein. A systematic review. Arch Intern Med 2007; 167:31-39.
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