April 1, 2005
UW study shows weight loss reduces markers of inflammation associated with increased risk of heart problems
In otherwise healthy obese women, weight loss is associated with significant decreases in biomarkers associated with cardiovascular risk, according to an article printed in the April 6 edition of the Journal of Clinical Endocrinology and Metabolism.
The article is based on research by Dr. Kevin O’Brien, associate professor of medicine at the University of Washington and colleagues at the University of Cincinnati; the researchers noted that these effects were proportional to the amount of weight lost, but did not depend on what kind of diet the women in the study used to lose weight.
“We measured levels of serum amyloid A (SAA) and C-reactive protein (CRP) in the study subjects, since elevated levels of these inflammatory markers are associated with increased cardiovascular risk,” O’Brien said.
“These proteins are also associated with inflammation. We knew prior to this study that levels of CRP decrease with weight loss, but it was not known whether SAA also goes down with weight loss.”
The researchers were also investigating whether the composition of the weight loss diets themselves would affect SAA and CRP levels. Blood levels of the chemicals were measured at the beginning of the study. The 41 participants were then placed on either a low fat diet or a very low carbohydrate, Atkins-type diet. After three months, the study participants who lost weight had significant decreases in both SAA and CRP. The decreases in SAA also correlated with reduction of insulin resistance.
“The dieters on the very low-carbohydrate diet had a significantly greater decrease in SAA, but their weight loss was also significantly greater,” O’Brien said. “The effects on the inflammatory markers were proportional to the amount of weight lost.”
Weight loss among the obese study participants was also associated with improvement in blood pressure readings: a reduction of about a point in both systolic and diastolic pressure for each kilogram of weight lost. Blood triglycerides went down about five points for every kilogram lost, emphasizing that the benefits of even modest weight loss extend to more traditional cardiovascular risk factors.
O’Brien pointed out that concerns persist about the long-term safety of very low carbohydrate diets.
“We were surprised that the levels of the inflammatory markers declined among the women who were on the very low-carbohydrate, high-fat and high-cholesterol diet, which we had expected would raise these markers,” O’Brien said. “Since the participants in this study were obese, the results may be quite different for someone who is only 10 to 15 pounds overweight, as their metabolic response to dietary fat and cholesterol may differ.”
He cautions that losing weight on extreme diets may, in the long run, work against people trying to improve levels of inflammatory markers, triglycerides and blood pressure if they are not able to sustain these dietary changes. Achieving sustained weight loss and its accompanying health improvements requires changes that can be maintained for the long haul.
“The findings of this research suggest that longer-term studies of the effects of weight loss and dietary composition on inflammatory markers are warranted,” O’Brien added.