Thermogenesis after a mixed meal: Role of leg and splanchnic tissues in men and women

To determine the relative contribution of splanchnic and leg tissues to postprandial thermogenesis, systemic and regional oxygen consumption rates were measured in nine women and eight men before and for 6 h after the consumption of a mixed meal that provided one-third of the daily energy needs. In women, the increase in splanchnic oxygen uptake accounted for 63 ± 12% of the postprandial increase in oxygen consumption, whereas in men it accounted for 35 ± 14% (P = not significant between women and men). Leg oxygen uptake accounted for 11 ± 4 and 10 ± 3% of the increase in postprandial oxygen consumption in women and men, respectively. The combined data suggest that ~48% of postprandial thermogenesis over 6 h occurs in splanchnic tissues, whereas 30-35% occurs in skeletal muscle. Thus the increase in oxygen consumption after a mixed meal is primarily localized to splanchnic tissues, and major reductions in postprandial thermogenesis are unlikely to be attributable solely to abnormalities of skeletal muscle metabolism.