Short-term consumption of a high-fat diet impairs whole-body efficiency and cognitive function in sedentary men

We recently showed that a short-term high-fat diet blunted exercise performance in rats, accompanied by increased uncoupling protein levels and greater respiratory uncoupling. In this study, we investigated the effects of a similar diet on physical and cognitive performance in humans. Twenty sedentary men were assessed when consuming a standardized, nutritionally balanced diet (control) and after 7 d of consuming a diet comprising 74% kcal from fat. Efficiency was measured during a standardized exercise task, and cognition was assessed using a computerized assessment battery. Skeletal muscle mitochondrial function was measured using P-31 magnetic resonance spectroscopy. The diet increased mean +/- SE plasma free fatty acids by 44% (0.32 +/- 0.03 vs. 0.46 +/- 0.05 mM; P < 0.05) and decreased whole-body efficiency by 3% (21 +/- 1 vs. 18 +/- 1%; P < 0.05), although muscle uncoupling protein (UCP3) content and maximal mitochondrial function were unchanged. High-fat diet consumption also increased subjects' simple reaction times (P < 0.01) and decreased power of attention (P < 0.01). Thus, we have shown that a high-fat diet blunts whole-body efficiency and cognition in sedentary men. We suggest that this effect may be due to increased respiratory uncoupling.-Edwards, L. M., Murray, A. J., Holloway, C. J., Carter, E. E., Kemp, G. J., Codreanu, I., Brooker, H., Tyler, D. J. Tyler, Robbins, P. A., Clarke, K. Short-term consumption of a high-fat diet impairs whole-body efficiency and cognitive function in sedentary men. FASEB J. 25, 1088-1096 (2011). www.fasebj.org