The effect of five days' fasting on skeletal muscle enzymes in obese men.

The effect of 120 hours' (five days) fasting on the activity of some enzymes of energy metabolism in skeletal muscles was investigated in six obese young men. The results revealed a significant decline in the activity of the following enzymes: triosophosphate dehydrogenase (by 20%), glycerol-3-phosphate dehydrogenase (by 24%), lactate dehydrogenase (by 13%), citrate synthase (by 20%), hydroxyacyl-CoA dehydrogenase (by 40%), while the hexokinase and malate dehydrogenase activities were not significantly altered. Contrary to muscles of non-obese healthy men (Vondra, Bass, Brodan, Kuhn, Andĕl, Veselková and Vítek 1982), a smaller decline of activities of the investigated enzymes occurred together with a paradoxical change of the enzyme pattern, namely a predominance of carbohydrate catabolism and a decline of the role of fatty acids in muscle energy metabolism.