OBJECTIVES: Worldwide, sugar-sweetened beverage (SSB) taxes are increasingly being implemented as a strategy for addressing the rising prevalence of obesity. In Brazil, a law drafted in 2017 proposed a 20% tax on SSB, but it is still waiting for approval. Thus, this study aims to estimate the impact of the introduction of a SSB tax on the variation of BMI and the incidence of type II diabetes in the adult Brazilian population. METHODS: This study was performed as follows: (i) an Almost Ideal Demand System (AIDS) was used to estimate the price elasticity of sugary drinks using Brazilian Consumer Expenditure Survey, 2017-2018; (ii) these price elasticities were used to compute variations in BMI , through energy balance equations and the consumption of SSB (Risk Factors Surveillance survey 2018); (iii) a Markov macrosimulation was used to estimate the impact of the variation in the BMI on the incidence of type II diabetes, based on the potential impact fraction (PIF). RESULTS: A price elasticity of -1.10 was found for sugary drinks, demonstrating consumer sensitivity to price variation. The calculations made pointed to an average reduction of the BMI of 1.37 Kg/m² and a potential of 11,187 years of life gained as a result of the reduction of type II diabetes over a time horizon of 5 years of taxation in Brazil. CONCLUSIONS: This study demonstrated that a 20% tax on sugary drinks would have a positive effect on the health of the Brazilian population. This taxation would help consumers to reshape their choices and allocate their consumption to healthier alternatives.