OBJECTIVE: To study the role of alimentary sensory stimulation on the therm
ic effect of food. SUBJECTS: Nine male healthy volunteers (age: 20 - 34 y,
body mass index (BMI): 17.4 - 25.3 kg/m(2)).
DESIGN AND MEASUREMENTS: Four experimental situations were investigated on
different days. Subjects: 1) ate a four course meal containing 2582 kJ (mea
l), 2) saw, smelt and tasted the same courses (alimentary sensory stimulati
on), 3) saw, smelt and tasted non-alimentary substances (non-alimentary sen
sory stimulation), 4) received directly into the stomach the previous meal
(tube feeding). Energy expenditure (EE) was measured over a 20 min rest per
iod, then for 110 min.
RESULTS: The changes over midday rest EE were: meal = +12.0%; alimentary se
nsory stimulation = +3.2%; non-alimentary sensory stimulation = -2.6%; tube
feeding = +5.7%. The increase in EE was higher after the meal than after e
ither alimentary sensory stimulation (P < 0.01) or tube feeding (P < 0.01);
the increases after the last two were, in turn, greater than after non-ali
mentary sensory stimulation (P < 0.05). Only after alimentary sensory stimu
lation, was the increment in EE significantly correlated with BMI (r = - 0.
700; P < 0.05),
CONCLUSIONS: The early phase of postprandial thermogenesis therefore depend
s on both sensory and metabolic events. Furthermore, the sensory component
was more pronounced in the lean subjects.