Objective: A recent economic approach suggests that people do not account for the long-term implications of unhealthy behaviours, preventing them from performing a fully rational trade-off between current benefits and future costs, leading to negative health outcomes. We examined whether the current allocation of time to physical activity among young people leads to outcomes that may affect their well being as youth and their longer--term life prospects. Design: The study group comprised a random sample of 1692 high-school students (14.8 ± 0.7 years old) from urban Santiago, Chile attending private and non-private schools. Setting: We measured physical activity habits accounting for time spent in class, studying and screen-based entertainment, hours of daily recreational activity and hours of weekly scheduled exercise. Obesity and abdominal obesity were diagnosed according to CDC/NCHS 2000, NHANES III and IDF criteria, respectively. Method: Logistic regression analysis was performed to assess the relationship between current physical activity habits, confounders and the likelihood of suffering from obesity and abdominal obesity. Results: Young people reporting the lowest allocation of time to physical activity, scheduled exercise and active play showed a higher risk of obesity and abdominal obesity. Those reporting moderate allocation of time to physical activity, scheduled exercise and active play were more likely to suffer from central obesity as defined by IDF criteria. Study participants attending partially subsidized schools showed the highest risk of obesity and central obesity. Conclusions: In this sample, young people appear not to be employing optimal strategies for making weight-related choices, since reduced physical activity, obesity and central obesity are proximate causes of metabolic and cardiovascular disorders.