Background: Health education is a part of health care concerned with raising people's awareness, enabling them to deal effectively with their illness , changing attitudes, and promoting healthy behaviors. Individual's behavior can be the main cause of health problems, and it also can be the main solution. Aim: determine the effect of implementing a health education program on nutritional behaviors and self-efficacy of overweight nursing students. Design: A quasi- experimental research design was used. Setting: the study was carried out at the Faculty of Nursing, Damanhur University at the Medical Surgical Nursing Department. Subjects: 108 overweight nursing students were assigned randomly by systematic random sampling into two equal groups (study and control groups), 54 students in each group. Tools: Four tools were used Tool (I) Nursing students' knowledge assessment about healthy nutrition. Tool (II) Nursing students' nutritional behavior assessment. Tool (III) Anthropometric measurements and Tool (IV) Nursing Student's Self-Efficacy Scale. Results: After the implementation of the health promotion program a statistically significant improvement was found in nursing student's nutritional behavior in favor to study group. There was statistically significant difference in body mass index for study group pre and post the program. A statistically significant difference was found in students' self-efficacy mean score pre and post the program implementation in study group. Conclusion: The results of the current study concluded that implementing health education program based on Pender health promotion model has a positive effect on improving nursing students' knowledge and self-efficacy leading to improving students' nutritional behavior. Recommendations: Conducting periodically routine screening by measuring body mass index for undergraduate nursing students who are at high-risk for obesity.