RESUMEN
OBJECTIVE: Adolescent diet, physical activity and nutritional status are generally known to be sub-optimal. This is an introduction to a special issue of papers devoted to exploring factors affecting diet and physical activity in adolescents, including food insecure and vulnerable groups. SETTING: Eight settings including urban, peri-urban and rural across sites from five different low- and middle-income countries. DESIGN: Focus groups with adolescents and caregivers carried out by trained researchers. RESULTS: Our results show that adolescents, even in poor settings, know about healthy diet and lifestyles. They want to have energy, feel happy, look good and live longer, but their desire for autonomy, a need to 'belong' in their peer group, plus vulnerability to marketing exploiting their aspirations, leads them to make unhealthy choices. They describe significant gender, culture and context-specific barriers. For example, urban adolescents had easy access to energy dense, unhealthy foods bought outside the home, whereas junk foods were only beginning to permeate rural sites. Among adolescents in Indian sites, pressure to excel in exams meant that academic studies were squeezing out physical activity time. CONCLUSIONS: Interventions to improve adolescents' diets and physical activity levels must therefore address structural and environmental issues and influences in their homes and schools, since it is clear that their food and activity choices are the product of an interacting complex of factors. In the next phase of work, the Transforming Adolescent Lives through Nutrition consortium will employ groups of adolescents, caregivers and local stakeholders in each site to develop interventions to improve adolescent nutritional status.