In this article, insights from psychology and behavioral economics are identified that help explain why it is hard to maintain healthy eating habits in modern food environments. Most eating decisions engage System 1, rather than System 2, processing, making it difficult for people to consistently make healthy choices in food environments that encourage overconsumption of unhealthy foods. The psychological vulnerabilities discussed include emotions and associations mattering more than reason, difficulty processing complex information, present-biased preferences and planning fallacy, status quo bias and defaults, and susceptibility to unhealthy foods that are in sight and, therefore, in mind. The article argues that these insights should convince us that supporting healthy eating habits and reversing the worldwide obesity epidemic will occur only if our food environments are changed in substantial ways, largely through policy changes. Such policies include restrictions on food marketing, requiring uniform front-of-package nutrition labeling, changing unhealthy food and beverage defaults to healthy ones, and taxing unhealthy foods and beverages. Psychology and behavioral economics should inform the design of these policies to maximize their effectiveness. (PsycINFO Database Record (c) 2020 APA, all rights reserved).