PLASMA-LIPID RESPONSE TO HYPOLIPIDEMIC DIETS IN YOUNG HEALTHY NONOBESE MEN VARIES WITH BODY-MASS INDEX

Lipid response to dietary fat is highly variable among individuals of a population. The aim of this study was to establish whether being ove rweight is one of the factors that determines this response. Forty-one non-obese healthy men were divided into two groups according to body mass index as follows: controls, <25 kg/m(2); overweight, >25 kg/m(2) but <30 kg/m(2). After consuming a saturated fat-rich diet (SAT diet: 38% fat, 20% saturated) for 4 wk, subjects were switched to a low fat diet [National Cholesterol Education Program (NCEP)-I diet: 28% fat, 1 0% saturated] for 4 wk and then to a monounsaturated fat-rich diet (MU FA diet: 38% fat, 22% monounsaturated) for 4 wk. Data were analyzed by Student's t test and two-way ANOVA for repeated measures. After consu ming the NCEP-I diet, the overweight subjects had a smaller decrease r elative to the SAT diet period in plasma total cholesterol [-0.30 vs. -0.67 mmol/L (-7 vs. -16%), P < 0.02] and low density lipoprotein-chol esterol concentrations [-0.24 vs. -0.55 mmol/L (-9 vs. -21%), P < 0.04 ] than controls. However, in the overweight subjects, the MUFA diet pr oduced a greater decrease in plasma triglycerides than in the controls relative to the SAT diet period [-0.36 vs. -0.03 mmol/L (-26 vs. -4%) , P < 0.006] and to the NCEP-I diet period [-0.29 vs. 0.01 mmol/L(-22 vs. 1%), P < 0.01). Plasma cholesterol concentrations changed to a les ser extent, and triglyceride concentration to a greater extent, in ove rweight but non-obese young men than in those of normal weight in resp onse to changes in dietary fat composition. Our data suggest that in t he diet treatment of obese hyperlipemic subjects, It is more important for them to lose weight than to change the fat composition of their d iets.