Although previous studies have identified the effect of social environment and individual behavior on adolescent obesity in the field of social science, much less is known about the association between adolescent educational expectations and obesity. This article draws on China Education Panel Survey (CEPS) 2013 to 2014 to examine the relationship between adolescent educational expectations and BMI/obesity. Results show that adolescents with college expectations have higher BMI and higher risk of obesity. Learning time partially mediates the relationship between adolescent college expectations and obesity. Additionally, the association between adolescent college expectations and BMI/obesity is stronger for males and urban students. The findings indicate that higher educational expectations may lead to health problems. School and family should perceive the health cost of high educational expectations to promote adolescent all-around development.