Why is America a land of low-calorie food claims yet high-calorie food intake? Four studies show that people are more likely to underestimate the caloric content of main dishes and to choose higher-calorie side dishes, drinks, or desserts when fast-food restaurants claim to be healthy (e.g., Subway) compared to when they do not (e.g., McDonald's). We also find that the effect of these health halos can be eliminated by simply asking people to consider whether the opposite of such health claims may be true. These studies help explain why the success of fast-food restaurants serving lower-calorie foods has not led to the expected reduction in total calorie intake and in obesity rates. They also suggest innovative strategies for consumers, marketers, and policy makers searching for ways to fight obesity. (c) 2007 by JOURNAL OF CONSUMER RESEARCH, Inc..