This research was aimed to determine the effect of educational intervention on healthy eating habits and physical activity levels of high school students. The research was conducted in two stages with a total of 800 students from 4 schools between the dates of 25.12.2016 - 31.05.2017. In the first stage, a questionnaire form consisting of 21 questions was applied to all students, and their height and weight measurements were collected. In the second stage, the planned educational intervention was implemented (n = 490) and the height and weight measurements of the students were collected again. The perception of students' body structures changed according to their genders before the intervention (p=.006), however, after the intervention, there was no correlation between the gender of students and their perception of their bodies. In addition, it was determined that the rate of those who stated that they, generally, had a healthy diet after the intervention increased from 38.8% to 52.2%. According to the results obtained from the research conducted, female students, at higher rates, perceive their weight incorrectly than male students. The intervention had little effect on the BMI of the students, while the proportion of those who had a healthy diet, and those who were physically active had increased. Based on the results obtained, it can be said that increasing the number of intervention programs and studies targeting adolescents will be effective in achieving positive results.