Background:Stress results in eating in the absence of hunger, possibly related to food reward perception.Hypothesis:Stress decreases food reward perception.Aim:Determine the effect of acute stress on food choice and food choice reward-related brain activity.Subjects:Nine females (BMI=21.5+/-2.2 kg/m(2), age=24.3+/-3.5 years).Procedure:Fasted subjects came twice to randomly complete either a rest or stress condition. Per session, two functional MRI scans were made, wherein the subjects chose the subsequent meal (food images). The rewarding value of the food was measured as liking and wanting. Food characteristics (for example, crispiness, fullness of taste and so on), energy intake, amount of each macronutrient chosen, plasma cortisol and Visual Analog Scale (VAS) hunger and satiety were measured.Results:Fasted state was confirmed by high hunger (80+/-5 mm VAS). Breakfast energy intake (3+/-1 MJ) and liking were similar in all conditions. Wanting was lower postprandially (Delta=-0.3 items/category, P<0.01). Breakfast decreased hunger (-42 mm VAS, P<0.01). Postprandially, energy intake (-1.1 MJ), protein intake (-14.7 g) and carbohydrate intake (-32.7 g all P<0.05) were lower. Fat intake was not different (-7.3, P=0.4). Putamen activity was not lower postprandially. Cortisol levels were increased in the stress condition (Area under the curve of cortisol: DeltaAUC=+2.2 x 10(4) nmol min(-1) l(-1), P<0.05). Satiety was lower after breakfast (-8 mm VAS, P<0.01). Postprandial energy intake, protein intake and carbohydrate intake were relatively higher compared with the rest condition, resulting from more choice for crispiness and fullness of taste (P<0.05). Brain activation was reduced in reward areas: amygdala, hippocampus and cingulate cortex (AUC=-13.33, -1.34, -2.56% blood oxygen level dependent (BOLD) s for choosing breakfast and AUC=-9.31, -1.25, -2.34%BOLD s<0.05 for choosing the second meal). Putamen activation was decreased postprandially (AUC=-1.2%BOLD s, P<0.05).Conclusion:Reward signaling and reward sensitivity were significantly lower under stress, coinciding with increased energy intake from food choice for more crispiness and fullness of taste. The changes in putamen activation may reflect specifically decreased reward prediction sensitivity.International Journal of Obesity advance online publication, 20 October 2009; doi:10.1038/ijo.2009.221.