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

Abstract

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), HDL3b (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.(ABSTRACT TRUNCATED AT 250 WORDS)

Fig 1

Mean levels of protein-stained HDL by particle diameter in 35 exercisers, 31 dieters, and 31 controls at baseline. The approximate size intervals for the HDL_3c HDL_3b HDL_3a HDL_2a, and HDL_2b, subclasses are shown [5]. There were no significant mean differences between groups at any diameter value.

Fig 2

Differences between exercisers and controls, dieters and controls, and exercisers and dieters for 7-month and 12-month changes in HDL-protein by particle diameter. The men were actively losing weight at 7 months, and had stabilized their weight loss at 12 months. The bars at the bottom of each graph give the statistical significance. Solid bars designate significance (P<0.05), and broken bars designate nonsignificance. Mean differences between groups are also presented after adjustment for changes in BMI by analysis of covariance.

Fig 3

Correlation coefficients between changes in HDL-protein and changes in BMI, percent body fat, and caloric intake in 35 exercisers and 31 dieters. Coefficients are plotted at each diameter value. The bars at the bottom of each graph give the statistical significance. Solid bars designate significance (P=0.05), and broken bars designate nonsignificance. A third bar designates the diameter values where the exercisers’ correlation coefficient is significantly different from that of the dieters (solid).

Fig 4

Multiple regression analyses for testing whether post-treatment HDL levels in 35 exercisers were more strongly related to weight-loss since baseline or to posttreatment weight (BMI). For example, the top figure displays the α and β regression coefficients for the model HDL_{7 mo}= intercept + α ΔBMI + βBMI_{7 mo}, where ΔBMI is the change in BMI between baseline and 7 months, and BMI_{7 mo} is the 7-month BMI measurement. The associated significance levels for the coefficients are given by the solid (P < 0.05) and broken bars (NS) at the bottom of the figure.

Fig 5

Correlation coefficients between changes in HDL-protein and changes in apo A-I and A-II concentrations in exercisers and dieters. Coefficients are plotted at each diameter value. Two bars at the bottoms of the graphs give their statistical significance. Solid bars designate significance (P < 0.05), and broken bars designate nonsignificance. A third bar designates the diameter values where the exercisers’ correlation coefficient is significantly different from that of the dieters (solid).