|Van Loan, Marta|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2008
Publication Date: 5/20/2009
Publication URL: http://jn.nutrition.org/cgi/reprint/139/2/222
Citation: Smilowitz, J., Wiest, M.M., Watkins, S.M., Teegarden, D., Zemel, M.B., German, B.J., Van Loan, M.D. 2009. Lipid metabolism predicts changes in body composition during energy restriction in overweight individuals. Journal of Nutrition. 139:222-229. Interpretive Summary: Obesity is a major public health issue for Americans. Medical costs associated with obesity related diseases and illnesses are in the billions annually. Research into treatment approaches that reduce the degree of obesity can save significant medical costs associated with diabetes, hypertension, and heart disease. We explored how understanding an individual’s blood lipids or fats can be used to predict success with a weight loss regimen. Blood samples from forty-five men and women were examined for a wide variety of fats in the blood stream prior to participation in a weight loss study. Based on fasting values for blood fats predictive equations were developed for changes in body weight and composition; specifically body fat and lean mass and waist circumference. The predictive equations demonstrated that initial blood fat levels could account for 20-40% of the observed changes in body composition. These findings suggest that circulating fats in the blood stream reflect fat metabolism during a weight loss intervention and may be helpful in designing weight loss programs to maximize fat loss with weight loss.
Technical Abstract: Dietary weight loss regimens could be more effective by selectively targeting adipose while sparing lean mass if predictive information about individuals’ lipid metabolic responses to a intervention were available. The objective of this study was to examine the relationships among changes in four anthropometric outcomes—1) weight, 2) waist circumference, 3) percent lean mass and 4) percent body fat--and comprehensive circulating lipid metabolites in response to energy reduction in overweight subjects. This was a cohort study (n=45) from a larger multi center (n = 106) weight loss trial. Stepwise regression was used to examine relationships among baseline circulating plasma fatty acids of 7 lipid classes, biochemical metabolites and diet to explain the variance of four anthropometric outcomes after intervention. No predictor variables were found to explain the variance in the percent change in body weight. Circulating baseline free fatty acid 18:1(n9) explained 25% of the variance of the percent change in waist circumference. Circulating baseline phosphatidylcholine 18:0 and free fatty acid 18:1(n9) together explained 41% of the variance in percent lean mass change. Circulating baseline phosphatidylcholine 18:0 explained 23% of the variance in percent body fat change. This study determined relationships among comprehensive and quantitative measurements of complex lipid metabolites and metabolic outcomes and changes in body composition. Measurements of baseline plasma circulating metabolites explained 20-40% of the variance in changes in body composition after a weight loss intervention. The results of this study suggest that circulating lipids reflect lipid metabolism in relation to changes in body composition.