To identify trajectories of Indonesian children and adolescent’s BMI-z scores between 1993 and 2014, examine whether the pattern differs by sex and assess associations with host, agent and environmental factors.

Longitudinal data were from the Indonesian Family Life Survey with up to five measurements of height and weight. Group-based trajectory models investigated changes in BMI-z score across time; differences by sex were investigated using random effect (mixed) models. The association between the trajectories and host, agent and environmental factors were examined using multinomial logistic regression.

Thirteen provinces in Indonesia.

Indonesian children and adolescents aged 6–18 years (n 27 394 for BMI-z trajectories; n 8805 for risk factor analyses).

Mean BMI-z score increased from –0·743 sd in 1993 to –0·414 sd in 2014. Four distinct trajectory groups were estimated with mean BMI-z increasing more rapidly in the most recent time periods. One group (11·7 % of participants) had a mean BMI-z entirely within the moderately underweight range; two had trajectories in the normal range and one (5·6 %) had a mean BMI-z starting in the overweight range but within the obesity range by 2014. There were differences in trajectory groups by sex (P< 0·001). Those born in 2000s, frequent consumption of meat, fast foods, soft drinks and fried snacks, and living in urban areas were associated with rapid gain weight.

These trajectories highlight the double burden of malnutrition and suggest that the prevalence of overweight and obesity is likely to increase substantially unless public health interventions are implemented.