To evaluate changes in dietary consumption and weight status of Brazilian adolescents. Data from the Brazilian National Dietary Survey of 2008–2009 and 2017–2018 were analysed, including food consumption and anthropometric data from 7425 adolescents (ages 10–19) in 2008–2009 and 8264 in 2017–2018. Foods were categorised into seventeen groups. Weight status was estimated using BMI-for-age-and-sex classification. Differences in mean consumption were assessed using linear regression adjusted for caloric intake and sex. Consumption was analysed by sex and income level, with analyses conducted in SAS, accounting for the sample design. Among boys aged 10–14, underweight rose from 2·3 to 4·5 %, obesity from 7·4 to 15·1 % and severe obesity from 0·7 to 2·1 %; normal weight fell from 67·4 to 50·7 %. Among girls, overweight increased (19·7–28·0 %), and normal weight decreased (69·5–57·5 %). Rice intake declined in all groups (e.g. –66 g/d in older boys). In younger boys, fruit (–18 g/d), coffee (–34 ml/d) and sweets (–21 g/d) decreased. Older boys showed reduced dairy products (–55 g/d) and increased fast food (+22 g/d). In older girls, fruit (–20 g/d), dairy products (–59 g/d) and sugary drinks (–90 ml/d) declined. Fast food rose only among those earning ≤ 0·5 minimum wage (+17 g/d). Over the decade, dietary quality worsened, and anthropometric indicators deteriorated. Income influenced consumption shifts, notably among low-income adolescents. Policies should promote healthy eating and limit ultra-processed food, especially for lower-income groups and boys.