According to CBS News, a small study published in Brain Imaging and Behavior used MRI scans to see how people’s brains responded to different food images at different times of the day. On two separate occasions, participants viewed 360 pictures, once in the morning and a day later at night. The foods ranged from high-calorie treats like ice cream, candy and fast food to low-calorie options such as fruits, vegetables and fish. The subjects showed greater neural responses to the high-calorie foods, but the evening MRIs showed a lower responses to both food groups in the brain areas that measure reward. The lead author says the reason we may keep eating late at night is because we are trying to get the same satisfaction or “high” from the food that is received during the daytime.