RÉSUMÉ
BACKGROUND: Sugar-sweetened beverages (SSBs) and breastfeeding practices have been recognized as important factors linked to children's weight status. However, no other studies have simultaneously investigated the role of each factor on children's conditional weight gain (CWG). OBJECTIVE: To evaluate the role of exclusive breastfeeding (EB) and the SSBs consumption on CWG from birth to the survey date among Brazilian preschool children (24-59 months old). METHODS: A nationally represented cross-sectional survey with complex probability sampling (n = 2421) was conducted. The outcome variable - CWG - represents how much an individual has deviated from its expected weight gain, given his or her prior weight. The multivariate linear regression to analyse the effects of EB and the consumption of SSBs on CWG were adjusted for economic status and maternal variables. RESULTS: There was a significantly protective effect of EB duration during the first year of life on CWG from birth to the survey date (-0.02 [-0.03; 0.00 95% confidence interval]); however, the SSBs intake promoted an effect on the weight gain that was 2.5-fold higher (0.05 [0.02; 0.08 95% confidence interval]) than the EB. CONCLUSION: As hypothesized, the exposure variables acted in opposite directions, but the harmful effect of SSBs intake had greater magnitude than the beneficial effect of EB on children's CWG.