Professionals in industries such as advertising and sales have used techniques of persuasion to enhance the efficacy of marketing campaigns and sales revenues. In contrast, health care has traditionally relied on the persuasive power of facts and evidence to encourage healthy behavior. The evidence suggests, however, that this current approach is failing. Health care experts and opinion leaders cite overwhelming evidence of an epidemic in diseases such as obesity and diabetes, despite numerous initiatives to educate the public how to prevent morbidity and mortality. Health captology, the application of persuasive technology to health care, attempts to leverage proven persuasive techniques to improve clinical outcomes.