Childhood obesity and sedentary lifestyles are now gaining a foothold in the Western world. The aim of this research was to analyse the influence of physical education classes on a healthy diet (i.e., Mediterranean diet). To this end, psychological constructs derived from the theory of self-determination and the theory of planned behaviour were taken into account, such as the satisfaction and frustration of basic psychological needs, motivation in physical education classes, and social cognition and intention. A total of 3415 secondary school students (13-19 years) participated in this study. A structural equation model was proposed that would explain the relationships between the variables mentioned above and the adherence to a Mediterranean diet. The results provide adequate fit indexes for the proposed model. Based on the results of the study, it was concluded that a high satisfaction perceived in the physical education classes would help to reinforce the intention of having a healthy diet and therefore help to generate a perdurable commitment to this habit.
Keywords: child obesity; healthy habits; motivation; physical education.