How does our brain value food?
In collaboration with the Cognitive Neuroscience Lab at Duke-NUS Medical School, we at the Clinical Nutrition Research Centre, conducted a study to examine how the brain values foods in people with different eating behavioural traits. Using state-of the art technology such as the fMRI and visual food stimuli, we found that compared to low dietary disinhibition participants, high dietary disinhibition participants showed brain signals reflecting higher valuation on foods, despite after being fed.
Lee Y*, Chong MF*, Liu JC, Libedinsky C, Gooley JJ, Chen S, Wu T, Tan V, Zhou M, Meaney MJ, Lee YS, Chee MW. Dietary disinhibition modulates neural valuation of food in the fed and fasted states. Am J Clin Nutr. 2013 May;97(5):919-25.
(*Joint first authors)
Background: Dietary disinhibition is a behavioral trait associated with weight gain and obesity. Because food choices are made according to the relative value assigned to each option, examination of valuation signals through functional magnetic resonance imaging (fMRI) may elucidate the neural basis for the association between dietary disinhibition and weight gain.
Objective: We examined how food valuation signals differ in the fed and fasted states between persons with high dietary disinhibition (HD) and low dietary disinhibition (LD).
Design: Sixteen men with HD and 14 with LD underwent fMRI once while fasted and once after being fed in a counterbalanced order. In-scanner preference to consume a test food relative to a neutral-tasting, neutral-health reference food was examined. The slope of magnetic resonance signal change corresponding to these food preferences constituted the food valuation signal that was compared across disinhibition group and satiety state.
Results: Both the HD and LD participants reported being less hungry (F(1,28) = 113.11, P , 0.001) after being fed than when fasted. However, food valuation signals in the ventromedial prefrontal cortex (vmPFC) differed between the groups (F(1,28) = 21.34, P , 0.001). Although LD participants showed attenuated vmPFC activity after being fed (t(13) = 4.11, P , 0.001), HD participants showed greater vmPFC activity in the fed than in the fasted state (t(15) = 22.56, P , 0.05).
Conclusions: Despite reporting normal decreases in hunger ratings after being fed, persons with HD have an altered neural valuation of food. This may be a mechanism underlying their propensity to overeat and gain weight. This trial was registered at clinicaltrials.gov as NCT00988819. Am J Clin Nutr doi: 10.3945/ajcn.112.053801