Intragastric vs oral feeding: effect on the thermogenic response to feeding in lean and obese subjects.

The aim of this study was to observe the effects of oropharyngeal stimulation on thermogenic response to feeding (TRF) in obese and healthy individuals. Resting energy expenditure was measured in eight normal-weight (BMI, in kg/m2: 22.9 +/- 1.7) and nine obese subjects (BMI: 36.5 +/- 7.2), once after the ingestion of a standardized meal and once after the intragastric administration of the same, blenderized meal. In control subjects, TRF was lower after intragastric than after oral feeding: 5.6 +/- 1.4% vs 8.0 +/- 1.8% of the ingested energy for intragastric vs oral feeding, respectively (P < 0.01), but in obese subjects no difference occurred (6.5 +/- 3.0% vs 6.1 +/- 2.0%). In obese subjects the response over 6 h after the oral meal was lower than in/control subjects (P < 0.01). Intragastric TRF was not different between the two groups. This study confirms our previous observation that TRF has two components in humans, and suggests that oropharyngeal stimulation elicits a greater TRF in normal-weight than in obese individuals.