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. 2003 Sep;78(3):430-5.
doi: 10.1093/ajcn/78.3.430.

Skeletal muscle enzymes as predictors of 24-h energy metabolism in reduced-obese persons

Eric Doucet  1 , Angelo Tremblay, Jean-Aimé Simoneau, Denis R Joanisse
Affiliations

Skeletal muscle enzymes as predictors of 24-h energy metabolism in reduced-obese persons

Eric Doucet et al. Am J Clin Nutr. 2003 Sep.

Abstract

Background: Little is known about the effects of weight loss on the relation between skeletal muscle enzymes and energy metabolism.

Objective: This study was performed retrospectively to investigate the relation between skeletal muscle enzymes and 24-h energy metabolism in obese persons before and after weight loss.

Design: Ten women and 9 men [with body mass indexes (in kg/m(2)) > 30] underwent a 15-wk weight-loss program (-700 kcal/d). Body weight and composition, 24-h energy metabolism (whole-body indirect calorimetry), and maximal activities of phosphofructokinase (EC 2.7.1.11), creatine kinase (CK; EC 2.7.3.2), citrate synthase (CS; EC 4.1.3.7), 3-hydroxyacyl-CoA dehydrogenase (HADH; EC 1.1.1.35), and cytochrome-c oxidase (COX; EC 1.9.3.1) were determined from biopsy samples of the vastus lateralis taken before and after weight loss.

Results: Before weight loss, fat-free mass (FFM) was the only predictor of 24-h energy expenditure (R(2) = 0.70, P < 0.001), whereas the cumulative variance in sleeping metabolic rate explained by FFM and fat mass (FM) was 83% (P < 0.001). After weight loss, CS (r = 0.45, P = 0.05) and COX (r = 0.65, P < 0.01) were significantly associated with 24-h energy expenditure, whereas CK (r = 0.53, P < 0.05), CS (r = 0.45, P < 0.05), COX (r = 0.64, P < 0.01), and HADH (r = 0.45, P = 0.05) were all significant correlates of sleeping metabolic rate. After weight loss, FFM, FM, and COX explained 84% (P < 0.01) of the variance in 24-h energy expenditure, whereas FFM, FM, and CK all contributed to the cumulative variance in sleeping metabolic rate explained by this model (R(2) = 0.82, P < 0.05).

Conclusion: Maximal activities of key skeletal muscle enzymes contribute to the variability in 24-h energy metabolism in reduced-obese persons.

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