title: Abdominal fat reducing outcome of exercise training: fat burning or hydrocarbon source redistribution?
abstract: Fat burning, defined by fatty acid oxidation into carbon dioxide, is the most described hypothesis to explain the actual abdominal fat reducing outcome of exercise training. This hypothesis is strengthened by evidence of increased whole-body lipolysis during exercise. As a result, aerobic training is widely recommended for obesity management. This intuition raises several paradoxes: first, both aerobic and resistance exercise training do not actually elevate 24 h fat oxidation, according to data from chamber-based indirect calorimetry. Second, anaerobic high-intensity intermittent training produces greater abdominal fat reduction than continuous aerobic training at similar amounts of energy expenditure. Third, significant body fat reduction in athletes occurs when oxygen supply decreases to inhibit fat burning during altitude-induced hypoxia exposure at the same training volume. Lack of oxygen increases post-meal blood distribution to human skeletal muscle, suggesting that shifting the postprandial hydrocarbons towards skeletal muscle away from adipose tissue might be more important than fat burning in decreasing abdominal fat. Creating a negative energy balance in fat cells due to competition of skeletal muscle for circulating hydrocarbon sources may be a better model to explain the abdominal fat reducing outcome of exercise than the fat-burning model.
authors.affiliation: a Laboratory of Exercise Biochemistry, Department of Sports Sciences, University of Taipei, Taipei, Taiwan.|b Graduate Institute of Rehabilitation Science, China Medical University, Taichung, Taiwan.
authors.forename: Chia-Hua
authors.initials: CH
authors.lastname: Kuo
authors.affiliation: c Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, VA, USA.
authors.forename: M Brennan
authors.initials: MB
authors.lastname: Harris
mesh_terms: D050153:Abdominal Fat / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006838:Hydrocarbons / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D055070:Resistance Training / Q000639:trends
chemical_list: D006838:Hydrocarbons
keywords: absorptiométrie biphotonique à rayons X (DEXA); anaerobic exercise; dual-energy X-ray absorptiometry (DEXA); entrainement aux poids; entrainement intermittent à haute intensité; exercice en aérobie; high intensity intermittent training; obesity; obésité; weight training