Exercise Induced Energy Deficit Does Not Impact Resting Plasma Free Fatty Acids and Glycerol

Abstract

Recently, negative energy balance induced by decreased energy intake was reported to cause resting plasma free fatty acid and glycerol concentrations to increase (1). Whether negative energy balance induced by increased energy expenditure affects biomarkers of lipid metabolism similarly is not known. PURPOSE: To compare effects of energy deficit induced by increased daily exercise on plasma markers of lipolyis with effects of increased exercise without energy deficit. METHODS: Fourteen men (23.4 ± 1.3 yrs, 74.0 ± 1.8 kg, 14.4 ± 1.4 % body fat, VO2peak58.2 ± 2.2 ml/kg/min) consumed a diet containing ∼55% CHO, 38% fat, and 0.9g protein/kg/d for 11 days. Day 1–4 (baseline, BL) energy intake (EI) matched EI and energy expenditure (EE) recorded the week before BL. Volunteers then added exercise at 55–65% VO2peak to expend an additional 1000 kcal/d for 7 days (EX). Seven volunteers increased EI to maintain energy balance (BAL), while seven maintained BL EI (DEF). EE was assessed by closed circuit spirometry, and body weight was recorded daily. Fasting plasma was analyzed for free fatty acid (FFA) and glycerol on days 3, 6, and 11. RESULTS: EI and EE for BAL was 3642 ± 271 and 3659 ± 276 kcal/d during BL and increased to 4594 ± 266 and 4655 ± 274 kcal/d during EX. EI for DEF was 3450 ± 97 kcal/d for BL and EX, while EE increased from 3491 ± 151 to 4447 ± 157 kcal/d for BL and EX respectively. BAL remained weight stable, while DEF lost 2.4 ± 0.21 kg (p<0.05). Resting FFA and glycerol values (mean ± SEM) are shown. * Difference between groups (p<0.05)TableThere were no differences within either group for FFA or glycerol from BL to EX. CONCLUSION: In contrast to what was observed with a one-day diet-induced energy deficit, a 7-d 1000 kcal/d exercise-induced energy deficit did not affect plasma markers of lipolysis, suggesting differential lipolytic regulation during dietary and exercise-induced energy deficit.