Effect of high-fat diet and exercise in the morning or evening on lipid subfractions among men with overweight/obesity: a randomised trial

Abstract Background Although main lipid fractions in the blood, such as HDL and LDL, are associated with risk of cardiovascular disease (CVD), the risk associated with different subfractions of these particles varies. For example, small dense LDL particles are associated with significantly increased CVD risk while larger LDL particles are not. Purpose To investigate the effect of a high-fat diet on serum lipid subfractions in men with overweight/obesity and to determine whether morning or evening exercise affected the lipid subfraction profile. Methods In a three-armed randomised trial, 24 men (aged 36±4 years, body mass index 31.2±2.3 kg/m2) consumed a high-fat diet (HFD; 65% energy from fat) for 11 days. One group of participants (n=8, control) did not exercise, while one group (n=8) exercised in the morning (06:30 hours) and one group (n=8) in the evening (18:30 hours) on days 6–10. We measured the effect of HFD, and that of morning or evening exercise, on fasting circulating lipoprotein subclass profiles determined using nuclear magnetic resonance spectroscopy. We performed a principal component analysis and partial least squares discriminant analyses to investigate patterns of changes in lipid subfractions after 5 days of HFD and a repeated measures ANOVA simultaneous component analysis (RM-ASCA) to determine multivariate changes in lipoprotein profiles between the three groups. To determine univariate effects of HFD on lipoprotein subclasses, we used Benjamini-Hochberg-adjusted paired samples t-tests. We used linear mixed models to determine between-group differences in lipoprotein subfractions after exercise in the morning or evening, compared to no exercise. Results Lipid subfraction profiles changed substantially after 5 days of HFD, with significant changes in 31 of 100 subfraction variables (adjusted p-values <0.05). Total serum cholesterol in LDL increased from 113±26 mg/dL to 122±26 mg/dL after 5 days of HFD (adjusted p=0.039) due to increased cholesterol in larger LDL particles (LDL-2 and LDL-3, Figure 1). Exercise induced a systematic change in lipid subfraction profiles, with small overall differences between morning versus evening exercise. Morning and evening exercise reduced serum concentrations of 20% and 24% of fasting lipid subfraction variables, respectively, compared to the control group (Figure 2). Evening exercise reduced fasting cholesterol concentrations in three LDL subfractions by 20%, 26% and 86%, respectively, while morning exercise only reduced concentration in the largest LDL particles by 12% (adjusted p-values <0.05 compared to the control group for all). Discussion and conclusion We found a marked change in lipid subfraction profiles after only five days of HFD among men with overweight/obesity. Exercise, either in the morning or in the evening, induced a substantial change in lipid subfraction profile compared with no exercise during an HFD. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation