Weight gain is associated with reduced striatal response to palatable food

Abstract

Consistent with the theory that individuals with hypofunctioning reward circuitry overeat to compensate for a reward deficit, obese versus lean humans have fewer striatal D2 receptors and show less striatal response to palatable food intake. Low striatal response to food intake predicts future weight gain in those at genetic risk for reduced signaling of dopamine-based reward circuitry. Yet animal studies indicate that intake of palatable food results in downregulation of D2 receptors, reduced D2 sensitivity, and decreased reward sensitivity, implying that overeating may contribute to reduced striatal responsivity. Thus, we tested whether overeating leads to reduced striatal responsivity to palatable food intake in humans using repeated-measures functional magnetic resonance imaging. Results indicated that women who gained weight over a 6 month period showed a reduction in striatal response to palatable food consumption relative to weight-stable women. Collectively, results suggest that low sensitivity of reward circuitry increases risk for overeating and that this overeating may further attenuate responsivity of reward circuitry in a feedforward process.

Figure 1.

Example of timing and ordering of presentation of pictures and drinks during the run.

Figure 2.

The gustatory manifold was anchored to the table. New tubing and syringes were used for each subject and the mouthpiece was cleaned and sterilized between uses.

Figure 3.

Coronal section showing less activation in the right caudate (12, −6, 24; Z = 3.44; FDR-corrected p = 0.03; p < 0.05) in the weight-gain group (N = 8; ≥2% BMI gain) versus the weight-stable group (N = 12; ≤2% BMI change) during milkshake receipt–tasteless receipt at 6 month follow-up compared with baseline with a scatter plot of the extracted caudate parameter estimates estimated for each group. PE, Parameter estimate.

Figure 4.

Scatter plot showing change in right caudate activation during milkshake receipt–tasteless receipt at 6 month follow-up compared with baseline as a function of change in percentage BMI. PE, Parameter estimate.