We sought to develop an index that incorporated various dietary and lifestyle behaviours that are associated with overweight/obesity status in adolescents. We assigned discrete scores into each component of the proposed index. The Diet-Lifestyle Index ranged from 11 to 57. We examined the accuracy of the index in relation to adolescents' body mass status using a sample of 2,008 students. The mean score of the index was 30.9 ± 5.2 for boys and 31.4 ± 4.7 for girls. The index was inversely associated with the odds of being obese/overweight (odds ratio = 0.93, 95% confidence interval = 0.90-0.96), after adjusting for age and gender. Particularly, an 11/57-unit increase of the index was associated with a 6% and 9% decrease in the odds of being overweight/ obesity in boys and girls, respectively (P > 0.001). Thus, the proposed Diet-Lifestyle Index could be a useful tool in a primary healthcare setting for preventing obesity in adolescence
