Background: Although physical activity is recognised to be an important determinant of health and nutritional status, few instruments have been developed to assess physical activity in developing countries. The aim of this study was to compare the validity of the short form of the International Physical Activity Questionnaire (IPAQ) and a locally adapted version of the Physical Activity Questionnaire for Adolescents (PAQA) for use in school going adolescents in rural and urban areas in Vietnam.

OH eating added a number of desirable foods and nutrients but was also associated with higher consumption of energy from fat and sugar products. Independent of household wealth and locality, pocket money and sex are important determinants of OH eating.

Eating out of home (OH) is nutritionally important in some developing countries. This study identifies the factors associated with eating OH in Vietnamese adolescents. Data was obtained from a cross-sectional cluster survey of 502 adolescents in rural and urban areas in Vietnam. Factors associated with eating OH were recorded with a Likert scale and analysed using factor analysis. Data on eating OH was collected using a frequency questionnaire and a 1-day 24 h recall. A first pattern "Convenience" incorporated preparation time, price, variety, taste, proximity and social aspects as items associated with eating OH. A second pattern "Nutritional and food safety concerned" reflects concerns with regard to hygiene, fat and salt content of the food prepared OH. Adolescents characterised by the convenience pattern were more likely (OR=1.51, P<0.001) to eat OH more frequently. The highest tertile of the Nutritional and food safety concerned pattern was less likely (OR=0.