Obesity is a serious public health problem within the United States. One promising approach to obesity prevention is health behavior change among college students, focusing on diet, sleep, and exercise. However, it remains unclear whether a health behavior change promotion program implemented in the classroom will effectively improve these health behaviors and negative outcomes related to obesity, particularly within classes of different topics. We examined the impact of a 6-week health behavior change program based on the Theory of Planned Behavior. Across several years, with two seemingly distinct samples of students from either a health psychology (n = 433) or a home gardening (n = 155) course, we conducted two studies and employed a single group, pre/post design in which self-reported and objectively measured health outcomes were assessed for change relative to the health promotion program. Participants selected one of three health behaviors and sought to meet current Centers for Disease Control and Prevention recommendations by setting goals, tracking behavior, and meeting with social support groups. Within both studies, dramatic changes emerged in the targeted health behaviors of fruit and vegetable consumption, sleep quantity and quality, and exercise. Moreover, several other health indicators improved among our subjective and objective health variables, and a few outcomes (i.e., subjective health, sleep quality, flexibility, loneliness) improved across all health behavior groups. Collectively, these results suggest this health behavior change program may be an effective way to elicit behavior change and highlight avenues for future remediation and prevention of obesity and related disease.