This study was planned to determine the effect of the web-based interactive nurse support program developed in line with the Health Promotion Model on healthy living behaviors and self-efficacy in individuals who gain weight after bariatric surgery. Mixed method is a research. In the qualitative part of the study, factors that prevent individuals from developing health behaviors will be determined. In the quantitative part of the study, a web-based training program will be prepared in order to reduce the perception of disability in individuals towards health-enhancing behavior, to adopt a healthy behavior style and to increase their self-efficacy. The universe of the study will be individuals who had bariatric surgery in the general surgery service between 2015-2019 in a university hospital in Turkey and gained weight again. Qualitative interviews will be held face to face with the video method over the "Zoom" application. "Criterion sampling method", one of the purposeful sampling methods used in qualitative research, will be used. In the qualitative part of the research, the individual in-depth interview method will be selected, and the "Semi-Structured Interview Form" will be used as the data collection tool. Interviews with individuals will continue until data saturation is reached. All interviews will be recorded in digital format, transcribed and subsequently imported into the qualitative analysis software MAXQDA. The quantitative part of the research is a randomized controlled experimental study. Randomization will be done by a statistician other than the researcher. Power analysis was calculated using G \* Power 3.1.9.7 program. With 80% effect size, 90% power and 0.05 significance level, the required sample size was determined as 28 individuals per group, and 56 individuals in total. It was decided to include 62 individuals, 31 individuals in the intervention group and 31 individuals in the control group, by taking 10% more of the calculated sample against the possibility of sample loss during the study. In the quantitative part of the study, the web-based interactive nurse support program will continue for 3 months, and the application will last for 6 months in total. A text message will be sent to their phones to remind individuals to use the website. The researcher will make phone calls with the intervention group for 6 months (12 times in total), twice a month. During telephone interviews, individuals will be talking about the use of the website, the points that are not understood or need to be emphasized, their application of health promotion behaviors, the obstacles they experience during the application and the suggestions for this. Healthy Lifestyle Behaviors Scale II, General Self-Efficacy Scale and Dutch Eating Behavior Questionnaire (DEBQ) will be used as measurement tools. Data collection forms will be applied to the intervention and control group three times in total, before starting the Web-based interactive nurse support program, at the end of the Web-based interactive nurse support program (in the 3rd month) and in the 6th month.After each assessment moment, the data obtained will be exported to the "Statistical Package for Social Sciences Software" (SPSS).