Behavioral studies demonstrate that uncontrolled eating, poor satiety responsiveness, and increased eating in the absence of hunger (1, 2) are more frequent among children with obesity (OB), who also find food more reinforcing (3) and are more responsive to food cues (2) than are children of healthy weight (HW). Altered circulating levels of satiety-related hormones (4, 5) are one possible explanation for such findings. Alternatively, previous functional MRI (fMRI) studies demonstrated hyperactivation in response to food images in reward regions in adults with OB (6, 7), potentially enhancing perception or anticipation of food reward (8–10). Existing findings suggest that children with OB are also hyperresponsive to food images in brain regions linked to motivation, reward, and cognitive control (11–13). These findings all point to the potential for a neurobiological basis of disturbed satiety in childhood OB, but the relationship and relative importance of peripheral hormone vs central responses remain uncertain.
To address these questions, we used fMRI to assess children’s central response to a standardized meal in a set of key appetite-processing brain regions that included the ventral striatum (VS), dorsal striatum (DS), medial orbitofrontal cortex (mOFC), amygdala, substantia nigra (SN)/ventral tegmental area (VTA) and insula. The degree of response to high-calorie food cues within these regions is heightened by fasting (14), is responsive to satiety-regulating hormones (15–17), reflects subjective satiety (18), and, critically, also predicts food choice and caloric intake (18, 19). We simultaneously monitored concentrations of circulating appetite-regulating hormones and glucose, all of which are known to modulate activation by food cues within several of these regions (15, 17, 20, 21).
We investigated the hypothesis that, in the selected brain regions noted above, children with OB would not reduce activation by high-calorie food cues after eating a standardized test meal relative to children of HW. We furthermore hypothesized that a hunger-promoting hormonal profile would be related to fMRI findings.
