the objective was to explore obese adolescents’ perceptions about obesity among students in the seventh to ninth grade of a public school in tamaulipas, mexico. this is a qualitative study. participants were 24 adolescents with a body mass index equal to or greater than the 95th percentile. semistructured interviews were conducted until data saturation was reached and the meaning was understood. the adolescents defined obesity according to standards of measurement. they identified the hereditary factor as the main obesity cause, tended to underestimate obesity and had low self-esteem. they reported problems to do physical exercise and get clothes in order to improve their image, and feel rejected by their peers in school. it was identified that these adolescents have psychological defense mechanisms against obesity and that some of them are making efforts to lose weight. obesity entails social and psychological health implications for persons suffering from this problem. interventions should be put in practice.