Persuasive technologies for promoting physical fitness, good nutrition, and other healthy behaviors have been growing in popularity. Despite their appeal, the evaluation of these technologies remains a challenge and typically requires a fully functional prototype and long-term deployment. In this paper, we attempt to help bridge this gap by presenting a method for using heuristic evaluation to evaluate persuasive technologies. We developed a set of 10 heuristics intended to find problems in persuasive technologies that would affect persuasive elements, adoption, or long-term effectiveness of the technologies. We compared the performance of Nielsen's heuristics to our heuristics on two persuasive technologies using 10 different evaluators. Using our heuristics, evaluators found more severe problems more frequently. In addition, the issues that found only by our heuristics were more severe and more relevant to persuasive, cultural, and informational issues of the interfaces evaluated. Our method can be helpful in finding problems in persuasive technologies for promoting healthy behaviors earlier in the design process.