Changes in plasma lipids and other cardiovascular risk factors during 3 energy-restricted diets differing in total fat and fatty acid composition

Background: The well-established relation between changes in dietary fatty acids and plasma lipids has been determined in energy-balance states. Wheth er this relation is altered in states of energy restriction and active weig ht loss is not clear. Objective: The objective of this 12-wk study was to compare the time course of lipid changes and other cardiovascular risk factors in 3 energy-restric ted diets (all 6500 kJ) with different total far and fatty acid composition s. Design: Sixty-two subjects with a body mass index tin kg/m(2)) >24 were str atified into 1 of 3 parallel dietary intervention groups: 1) a very-low-fat (VLF) diet (10% of energy from fat, 3% from saturated fat), 2) a high-satu rated-fat (HSF) diet (32% of energy from fat; 17% from saturated fat), and 3) a high-unsaturated-fat (HUF) diet (32% of energy from fat; 6% from satur ated fat). Results: After 12 wk, LDL cholesterol decreased by 0.66 +/- 0.11 ((x) over bar + SEM) and 0.68 +/- 0.12 mmol/L (approximate to 20%) with the VLF and H UF diets, respectively, compared with a decrease of only 0.24 +/- 0.11 mmol /L (7%) with the HSF diet (P < 0.02 between groups). Diet affected the time course of changes in HDL cholesterol with both high-fat diets, resulting i n smaller reductions in HDL cholesterol at weeks 1 (P = 0.0004) and 3 (P = 0.02); however, these differences were no longer apparent by 12 wk. Overall weight loss was 8.6 +/- 0.4 kg (9.7%) and waist circumference decreased by 7.3 +/- 5 cm (8%) for the combined groups, with no significant differences between diets. Conclusions: Significantly greater decreases in LDL cholesterol during acti ve weight loss are achieved with diets low in saturated fatty acids. Change s in HDL cholesterol between diets appear dependent on both the fat content of the diet and the duration of energy restriction.