Acute stress potentiates brain response to milkshake as a function of body weight and chronic stress

OBJECTIVE: Stress is associated with an increased intake of palatable foods and with weight gain, particularly in overweight women. Stress, food and body mass index (BMI) have been separately shown to affect amygdala activity. However, it is not known whether stress influences amygdala responses to palatable foods, and whether this response is associated with chronic stress or BMI. DESIGN: A total of 14 overweight and obese women participated in a functional magnetic resonance imaging (fMRI) scan as they consumed a palatable milkshake during script-driven, autobiographical, guided imagery of stressful and neutral-relaxing scenarios. RESULTS: We report that a network including insula, somatomotor mouth area, ventral striatum and thalamus responds to milkshake receipt, but none of these areas are affected by stress. In contrast, whereas the left amygdala responds to milkshake irrespective of condition, the right amygdala responds to milkshake only under stressful conditions. Moreover, this right amygdala response is positively associated with basal cortisol levels, an objective measure of chronic stress. We also found a positive relationship between BMI and stress-related increased response to milkshake in the orbitofrontal cortex (OFC). CONCLUSION: These results demonstrate that acute stress potentiates response to food in the right amygdala and OFC as a function of chronic stress and body weight, respectively. This suggests that the influence of acute stress in potentiating amygdala and OFC responses to food is dependent upon individual factors like BMI and chronic stress. We conclude that BMI and chronic stress play a significant role in brain response to food and in stress-related eating. International Journal of Obesity (2013) 37, 309-316; doi:10.1038/ijo.2012.39; published online 20 March 2012