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High dietary fat intake increases fat oxidation and reduces skeletal muscle mitochondrial respiration in trained humans

journal contribution
posted on 2018-06-01, 00:00 authored by Jill J Leckey, Nolan J Hoffman, Evelyn B Parr, Brooke L Devlin, Adam Trewin, Nigel K Stepto, James P Morton, Louise M Burke, John A Hawley
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.

History

Journal

FASEB journal

Volume

32

Issue

6

Pagination

2979 - 2991

Publisher

Federation of American Societies for Experimental Biology

Location

Bethesda, Md.

eISSN

1530-6860

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2018, FASEB