Metabolic and Sensory Influences on Odor Sensitivity in Humans

Our olfactory sense plays an important role in eating behavior by modulating our food preferences
and intake. However, hunger or satiety may also influence how we perceive odors. Albeit
speculative, contradictory results found in the past may have resulted from confounding by type
of meal that participants ate to induce satiety. We aimed to investigate the influence of hunger state
on olfactory sensitivity, comparing hunger to satiety using 2 different types of lunch to control
for sensory-specific satiety. Odor detection thresholds were measured in 2 groups of participants
(39 per group, 18–40 years), under 3 conditions: when hungry (twice), after a sweet lunch, and
after a savory lunch. One group had their detection thresholds tested for a sweet odor, whereas
in the other group, sensitivity to a savory odor was measured. Differences in olfactory sensitivity
conditions were analyzed using linear mixed models. Participants had higher scores on the odor
sensitivity task in a hungry versus satiated state (P = 0.001). Within the satiated condition, there was
no effect of type of lunch on odor sensitivity. In conclusion, hunger slightly enhances sensitivity
to food odors, but did not significantly depend on the type of food participants ate, suggesting no
clear influence of sensory-specific satiety.