This paper investigates whether and why laws requiring chain restaurants to post calories on menus and menu boards work. We develop a model of calories consumed that highlights multiple potential channels through which these laws influence choice and that outlines an empirical strategy to disentangle these alternatives. We test the predictions of our model using data from the Behavioral Risk Factor Surveillance System on body mass index and consumer well-being, as well as our own surveys on how the law influences where people eat and how randomized exposure to calorie information affects feelings toward menu items. Viewed in its totality, our results are consistent with an economic model in which calorie labels influence consumers both by providing salient information and by imposing a welfare-reducing moral cost (or feelings of guilt) on unhealthy eating.