We studied the independent and combined effects of exercise training and
weight loss on blood
lipids under fixed diet and exercise conditions. Twenty-one obese sedentary men were randomly allocated to one of four treatment groups: (1) inactive and constant weight (control), (2) exercise training and constant weight, (3) inactive and
weight loss, and (4) exercise training and
weight loss. There were three study periods: a 3 week baseline period inactive and on an isocaloric diet, a 12 week treatment period, and a 3 week weight stabilization period. Exercise consisted of treadmill walking at an energy cost of 3500 kcal/wk for groups 2 and 4 with replacement caloric intake only in group 2. Group 3 reduced caloric intake by 3500 kcal/wk during the treatment period.
Weight loss for groups 3 and 4 were 13.4 pounds and 13.7 pounds, respectively. Maximal
oxygen uptake (mL/min) increased 6% in both exercise groups (2 and 4), and percent body fat decreased only in these groups. Regression analysis by group assignment on
HDL cholesterol (HDL-C) showed that the inactivity-
weight loss modality (group 3) and the exercise-constant weight modality (group 2) each significantly increased HDL-C, with an additive effect of exercise and
weight loss (group 4). The rate of HDL-C change differed significantly between groups (P = 0.01). HDL-C increased 0.63, 0.61, and 1.89 mg/dL per 3 weeks or 2%, 2.4%, and 5.5% above baseline levels in groups 2, 3, and 4, respectively, while the control group decreased 0.11 mg/dL. Plasma
triglycerides and
very low-density lipoprotein (
VLDL) cholesterol increased with exercise at constant weight (group 2) and decreased with exercise associated with
weight loss (group 4). In conclusion, exercise and
weight loss separately and independently increase HDL-C, and their effects are additive.