Increase in skeletal muscle fatty acid binding protein (FABPC) content is directly related to weight loss and to changes in fat oxidation following avery low calorie diet

Aims/hypothesis. There is increasing evidence that intracellular fatty acid binding proteins (FABPc's; 15 kD) function as vehicles of cytosolic fatty acid transport. We studied skeletal muscle cytosolic FABPc, and enzymes ref lecting beta -oxidation and oxidative capacity (3-hydroxyacyl-CoA dehydroge nase, HAD, and citrate synthase, CS) in relation to weight loss and changes in substrate utilisation in a group of 35 obese women and obese men with T ype II (non-insulin-dependent) diabetes mellitus (women = 27, men = 8). Methods. Muscle biopsies (vastus lateralis), and measurements of body compo sition, resting energy expenditure and respiratory exchange ratio were take n before and after dietary intervention (by means of a very low calorie die t). Results. Muscle FABPc tended to increase after diet (178 +/- 13 vs 204 +/- 12 mg.gww(-1), p = 0.06), whereas there were no changes in CS (10.5 +/- 0.7 vs 11.1 +/- 0.6 U.gww(-1)) and HAD (11.2+/-0.7 vs 11.7+/-0.6 U.gww(-1)). T here was a positive relation between the increase in FABPc as result of die t and the amount of weight lost (p < 0.01; adjusted R-2, 15.4%). even when adjusted for mean body weight, and changes in CS and in HAD by partial regr ession analysis. Interestingly, the increase in FABPc was positively relate d to increases in resting fat oxidation (adjusted R-2, 24%), even when adju sted for mean resting fat oxidation, and changes in CS and in HAD. Conclusion/interpretation. In conclusion, the ability to increase muscle FA BPc could be directly related to weight loss and to changes in fat oxidatio n following dietary intervention in obesity and Type II (noninsulin-depende nt) diabetes mellitus.