ARS | Publication request: Dietary fat and not calcium supplementation or dairy product consumption is associated with changes in anthropometrics during a randomized, placebo-controlled energy-restriction trial

Submitted to: Nutrition and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 2011
Publication Date: October 5, 2011
Citation: Smilowitz, J.T., Wiest, M.M., Teegarden, D., Zemel, M.B., German, J.B., Van Loan, M.D. 2011. Dietary fat and not calcium supplementation or dairy product consumption is associated with changes in anthropometrics during a randomized, placebo-controlled energy-restriction trial. Nutrition and Metabolism. 8:67.

Interpretive Summary: Dieting interventions usually focused on weight loss as the most important change for health with little attention given to other health related parameters. One clinical marker of health status is change in cholesterol, but there are many types of fat in one’s blood that can change during weight loss and may be important for health. We examined changes in blood fats or lipids during weight loss in overweight and obese adults following 3 different weight loss interventions. All participants reduced their caloric intake by 500 calories. Group 1 group added 3-4 servings of dairy foods to their weight loss menu, group 2 added an equivalent amount of calcium via supplements to match the dairy diet and group 3 took a placebo supplement. After 12 weeks of weight loss we found that overall caloric restriction was significantly related to the changes in body weight and composition; however, after correcting for differences in caloric intake and protein, there were no differences among the diet groups in the changes in body weight, body composition, or in blood lipids. Additional data analysis revealed that dietary saturated fat, widely believed to be “bad” fat, was not associated with changes in blood lipid levels. However, the overall dietary fat composition was related to the change in body composition of these overweight and obese adults.

Technical Abstract: Insufficient calcium intake has been proposed to cause unbalanced energy partitioning leading to obesity. However, weight loss interventions including dietary calcium or dairy product consumption have not reported changes in lipid metabolism measured by the plasma lipidome. Methods. The objective of this study was to determine the relationships between dairy product or supplemental calcium intake with changes in the plasma lipidome and body composition during energy restriction. A secondary objective of this study was to explore the relationships among calculated macronutrient composition of the energy restricted diet to changes in the plasma lipidome, and body composition during energy restriction. Overweight adults (n = 61) were randomized into one of three intervention groups including a deficit of 500kcal/d: 1) placebo; 2) 900 mg/d calcium supplement; and 3) 3-4 servings of dairy products/d plus a placebo supplement. Plasma fatty acid methyl esters of cholesterol ester, diacylglycerol, free fatty acids, lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine and triacylglycerol were quantified by capillary gas chromatography. Results. After adjustments for energy and protein (g/d) intake, there was no significant effect of treatment on changes in weight, waist circumference or body composition. Plasma lipidome did not differ among dietary treatment groups. Stepwise regression identified correlations between reported intake of monounsaturated fat (% of energy) and changes in % lean mass (r = -0.44, P < 0.01) and % body fat (r = 0.48, P < 0.001). Polyunsaturated fat intake was associated with the % change in waist circumference (r = 0.44, P < 0.01). Dietary saturated fat was not associated with any changes in anthropometrics or the plasma lipidome. Conclusions. Dairy product consumption or calcium supplementation during energy restriction over the course of 12 weeks did not affect plasma lipids. Independent of calcium and dairy product consumption, short-term energy restriction altered body composition. Reported dietary fat composition of energy restricted diets was associated with the degree of change in body composition in these overweight and obese individuals.