Design and evaluation of an intervention to prevent overweight and obesity in Mexican urban public high schools

To prevent overweight and obesity among teenagers, an intervention targeted to 40 Mexico City public high schools was conducted by mandate of the Mexican Ministry of Education. The intervention was designed by conducting formative research to identify students' prevalence of key health indicators, and stakeholders perceived barriers/facilitators about key intervention strategies that were proposed by international and national experts. Intervention strategies were implemented on school physical activity (PA) areas and cafeterias (promotion and availability of fruits/vegetables, fat reduced dairy products, and water/low sugar beverages). Gender-oriented strategies were developed to promote PA in women. These strategies were supported by a communication campaign and educational activities. Process and impact evaluation (RCT design) was conducted including anthropometric, diet, psychosocial, market, and PA surveys, as well as focus groups and in-depth interviews with key stakeholders. Implementation barriers relate with students' health concerns about light-foods, perceived low quality/price ratio of fruit/vegetables, reduced availability of free water, curricula design, lack of availability and poor conditions of PA areas, as well as gender-related barriers favoring performance of “male” preferred sports. Positive impact was obtained in students' participation on PA school activities, and fruit (9.3 g/day, p=0.052) and vegetable (130.3 g/day, p=0.002) intake. As expected, no positive impact on nutrition status was demonstrated after one semester of intervention. Extended implementation time is needed for full adoption of proposed strategies. This study will contribute to the development of culturally-accepted interventions and public policy initiatives targeted to adolescents to overcome obesity epidemic and prevent chronic diseases in Hispanic population.