How to exercise to increase lipolysis and insulin sensitivity: Fasting or following a single high-protein breakfast

Abstract

BACKGROUND: The purpose of this study was to investigate the lipolysis response and insulin sensitivity to high-intensity interval exercise (HIIE) upon fasting (HIIEFAST) and following the intake of a high-protein breakfast (HIIEHPFED). METHODS: Overweight men participated in two sessions of HIIE after an overnight fast and post-HPFED with an interval of one week. Metabolic biomarkers were assessed before, immediately after, and 3h post-exercise. To evaluate the metabolic effects of HIIE, two-way repeated-measures ANOVA was used. RESULTS: Glycerol levels increased immediately after HIIEFAST and HIIEHPFED (P = 0.0001) and decreased 3h after exercise in both states (P = 0.001). There were no significant changes in free fatty acid (FFA) levels immediately after exercise, but a significant increase was observed 3h after exercise compared to the baseline and immediately after exercise in HIIEFAST and HIIEHPFED (P = 0.0001). Insulin sensitivity was increased for 3h after HIIEHPFED compared to the baseline and immediately after exercise (P = 0.04). CONCLUSIONS: These findings suggest that fasting during exercise is not necessary for the greater stimulation of lipolysis and an increase in insulin sensitivity and that exercise following a high-protein breakfast can have a similar effect in overweight young men.