Thermogenesis in relation to feeding and exercise training.

Tube-fed rats gain more weight than meal-fed rats when fed isocaloric diets. Human volunteers were fed on separate occasions isocaloric meals by mouth or by gavage and resting metabolic rate was measured for 90 min postprandially. Resting metabolic rate was greater in meal-fed than in tube-fed especially in the period following meal digestion. These results suggest that ingestion of food through sensory stimulation activates oxidative processes which may be under endocrine control. In tube-feeding where sensory inputs are absent, a reduction in meal thermogenesis is observed.