Food reward responsivity task: After the scan we will preform a progressive food reward responsivity task41. In this task, participants work to earn points toward a snack food reward of their choice (e.g., small servings of chips, peanut butter cups, skittles, popcorn). Participants first perform a taste test of 1g of each food and rate the on cross-modal visual analogue scales. They then select the snack food they want to earn. In the second phase, three boxes varying in shape and color are displayed on a computer screen (like a slot machine display). Points can be earned each time the shapes match in color and shape if the subject makes a button press. The task starts at a variable ratio 1/4 schedule meaning that, on average, one point is awarded for four button presses. The progressive ratio schedule for the food item doubles (VR8, VR16, VR32) each time they earn ten points. A total of ten points will be worth 1/2 standard portion of the food (per the nutritional information for the snack). Participants play for as long as they like. The break point at which the participant stops button pressing for food will be used as the behavioral measure of anticipatory food reward (i.e., how many button presses are made in total before the subject stops). This food reward responsivity task shows 2-7 day test-retest reliability (r = .80)21. With regard to the validity of this task, subjects who work harder for snack foods eat more food ad libitum, subjects who rate the snack foods as more hedonically pleasurable work harder for the snack foods, subjects work harder for food when they are food deprived, and obese subjects work for more food than lean subjects21,41,43.