EFFECTS OF WEIGHT-LOSS BY EXERCISE AND BY DIET ON APOLIPOPROTEINS A-I AND A-II AND THE PARTICLE-SIZE DISTRIBUTION OF HIGH-DENSITY-LIPOPROTEINS IN MEN

We studied separately the effects of weight-loss by dieting or by running on apolipoprotein (apo) A-I, apo A-II, and high-density lipoprotein (HDL) subfractions in sedentary, moderately overweight men assigned at random into three groups: exercise without calorie restriction, calorie restriction without exercise, and control. The absorbance of protein-stained polyacrylamide gradient gels was used as an index of mass concentrations for five HDL subclasses that have been identified by their particle sizes: HDL3c (7.2 to 7.8 nm), HDL2b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12.9 nm). During the 1-year trial, the exercisers ran (mean ± SD) 15.6 ± 9.1 km/wk, and the dieters reported eating 340 ± 71 fewer calories per day than at baseline. Total body weight and fat weight were both reduced significantly more in dieters (-7.2 ± 4.1 and -6.2 ± 4.1 kg, respectively) and in exercisers (-4.0 ± 3.9 and -4.6 ± 3.5 kg) than in controls (0.6 ± 3.7 and -0.7 ± 2.7 kg). As compared with mean changes in controls, exercisers and dieters each decreased HDL3b and increased HDL2b. Exercisers also significantly increased plasma apo A-I concentrations. Analysis of covariance was used to statistically adjust the mean lipoprotein changes for the effects of weight-loss. The adjustment eliminated the significant reductions in HDL3b and the significant increases in HDL2b in exercisers and dieters, and it eliminated the significant increase in apo A-I in exercisers. When adjusted, the dieters' mean changes in HDL2b had significantly decreased relative to those of both exercisers and controls. These results suggest that the changes in HDL3b, HDL2b, and apo A-I during 12 months of exercise could be due to metabolic changes associated with exercise-induced weight-loss. Reduced calorie flux or other factors appear to attenuate the increase in HDL2b and apo A-I during diet-induced weight-loss. © 1992.