We examined whether a belief in weight as malleable (an incremental theory) leads to healthier eating than a belief that weight is fixed (an entity theory). Participants with incremental theories of weight consumed fewer calories from high‐calorie foods in a lab‐based taste‐test than did those with more entity theories of weight. This pattern held correlationally, with naturally occurring theories of weight (Study 1), and when we experimentally manipulated participants’ theories of weight (Study 2). A third study provided evidence that differences in self‐efficacy regarding food mediate the relationship between theories of weight and eating behavior (Study 3). One way to encourage healthy eating might be to develop interventions that encourage more incremental views of weight.