Olfactory decoding is positively associated with ad libitum food intake in sated humans

The role of olfaction in eating behavior and body weight regulation is controversial. Here we used functional magnetic resonance imaging to test whether central olfactory coding is associated with internal state, food intake, and change in body weight over one year in healthy human adults. Since odor quality and category are coded across distributed neural patterns that are not discernible with traditional univariate analyses, we used multi-voxel pattern analyses to decode patterns of brain activation to food versus nonfood odors. We found that decoding accuracies in the piriform cortex and amygdala were greater in the sated compared to hungry state. Sated decoding accuracies in these and other regions were also associated with post-scan ad libitum food intake, but not with weight change. These findings demonstrate that the fidelity of olfactory decoding is influenced by internal state and is associated with immediate food intake, but not longer-term body weight regulation.