Abstract
OBJECTIVE: To examine the trajectories of BMI in Indonesian adults from 1993 to 2014, investigating different patterns by sex and birth cohort. DESIGN: Longitudinal study: secondary data analysis of the Indonesian Family Life Survey, a large-scale population-based longitudinal study, had their height and weight measured up to five times throughout the 21-year study period (1993-2014). The change in BMI across time was estimated using group-based trajectory models, then differences by sex and birth cohort were investigated using random effect (mixed) models. SETTING: Thirteen out of twenty-seven provinces in Indonesia. PARTICIPANTS: Indonesian adults aged 19 years and older (n 42 537) were included in the analysis. RESULTS: Mean BMI in adults increased between 1993 (21·4 kg/m(2)) and 2014 (23·5 kg/m(2)). The group-based trajectory model found three distinct groups with mean BMI increasing more rapidly in the most recent time periods. The first group (56·7 % of participants) had a mean BMI entirely within the normal weight range; the second group (34·7 %) started in the normal weight category and were obese, on average by the end of the study period; and the third group (8·6 %) were always in the obese category, on average. The shape of these three trajectories differed by gender (P < 0·001) and birth cohort (P < 0·001). CONCLUSIONS: The mean BMI among Indonesian adults has increased between 1993 and 2014, driven by those in the most recent birth cohorts. Our findings support the urgent need for targeted overweight and obesity prevention and intervention programmes in Indonesia.