Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia.
Institute of Sport, Exercise, and Active Living, Victoria University, College of Sport and Exercise Science, Melbourne, Victoria, Australia.
FASEB J. 2018 Jun;32(6):2979-2991. doi: 10.1096/fj.201700993R. Epub 2018 Jan 17.
High-fat, low-carbohydrate (CHO) diets increase whole-body rates of fat oxidation and down-regulate CHO metabolism. We measured substrate utilization and skeletal muscle mitochondrial respiration to determine whether these adaptations are driven by high fat or low CHO availability. In a randomized crossover design, 8 male cyclists consumed 5 d of a high-CHO diet [>70% energy intake (EI)], followed by 5 d of either an isoenergetic high-fat (HFAT; >65% EI) or high-protein diet (HPRO; >65% EI) with CHO intake clamped at <20% EI. During the intervention, participants undertook daily exercise training. On d 6, participants consumed a high-CHO diet before performing 100 min of submaximal steady-state cycling plus an ∼30-min time trial. After 5 d of HFAT, skeletal muscle mitochondrial respiration supported by octanoylcarnitine and pyruvate, as well as uncoupled respiration, was decreased at rest, and rates of whole-body fat oxidation were higher during exercise compared with HPRO. After 1 d of high-CHO diet intake, mitochondrial respiration returned to baseline values in HFAT, whereas rates of substrate oxidation returned toward baseline in both conditions. These findings demonstrate that high dietary fat intake, rather than low-CHO intake, contributes to reductions in mitochondrial respiration and increases in whole-body rates of fat oxidation after a consuming a high-fat, low-CHO diet.-Leckey, J. J., Hoffman, N. J., Parr, E. B., Devlin, B. L., Trewin, A. J., Stepto, N. K., Morton, J. P., Burke, L. M., Hawley, J. A. High dietary fat intake increases fat oxidation and reduces skeletal muscle mitochondrial respiration in trained humans.
高脂肪、低碳水化合物（CHO）饮食会增加全身脂肪氧化率，并下调 CHO 代谢。我们测量了底物利用和骨骼肌线粒体呼吸，以确定这些适应是由高脂肪还是低 CHO 供应驱动的。在一项随机交叉设计中，8 名男性自行车运动员连续 5 天摄入高 CHO 饮食[>70%能量摄入（EI）]，然后摄入等能量的高脂肪（HFAT；>65%EI）或高蛋白饮食（HPRO；>65%EI），CHO 摄入量限制在<20%EI。在干预期间，参与者进行了日常运动训练。在第 6 天，参与者在进行 100 分钟亚最大稳态自行车运动和大约 30 分钟计时赛之前，先摄入高 CHO 饮食。经过 5 天的 HFAT 后，休息时，辛酰肉碱和丙酮酸支持的骨骼肌线粒体呼吸以及解偶联呼吸减少，运动时全身脂肪氧化率升高，与 HPRO 相比。在高 CHO 饮食摄入 1 天后，HFAT 中的线粒体呼吸恢复到基线值，而在两种情况下，底物氧化率都恢复到基线值。这些发现表明，高膳食脂肪摄入，而不是低 CHO 摄入，有助于在摄入高脂肪、低碳水化合物饮食后减少线粒体呼吸并增加全身脂肪氧化率。
