Background Obesity is a worldwide public health problem, and large disparities between racial groups have been reported. The North American literature suggests that racial discrimination can accelerate the increase in body weight throughout life. As racism in Brazil has different and specific facets, our study aims to describe the racial difference in body weight and BMI (kg/m²) gain in four-years follow-up and to investigate whether racial discrimination changes these trajectories among Black and Brown individuals.

Methods The present study compares body weight and BMI changes between the 1st (2008–2010) and the 2nd visits (2012–2014) of 13,133 participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) according to race/skin color. In order to investigate whether racial discrimination predicts greater weight and BMI gain in Blacks and Browns (N=5,983), we used mixed-regression models. Information on racial discrimination, assessed by the modified version of the Lifetime Major Events Scale, and on sociodemographic, behavioral, and depressive episode factors were obtained at the 1st visit.

Results Mean age of participants was 52 years, 54% were female, 54% self-declared as White, 29% as Brown and 17% as Black. The median follow-up time was 3.9 years. During the study period Whites, Blacks and Browns gained an average 1.2 kg, 1.2 kg, and 1.4 kg, respectively, corresponding to an average increase in BMI of 0.60, 0.56 and 0.65 kg/m², respectively (p>0.05). Racial was reported by 6.3% of Brown and 32.1% of Black participants. The weight gain was greater among Black (2.1 kg versus 1.0 kg, p<0.001) and Brown individuals (1.9 kg versus 1.1 kg, p=0,02) who reported racial discrimination as compared to those who did not report. Mixed-effects regression models demonstrated that Blacks who reported racial discrimination had greater weight and BMI increases than those who did not report, even after adjustment by potential confounders (age, sex, education and income). These results remained statistically significant even after adjusting for mediating variables of the association between discrimination and weight/BMI gain (smoking, physical activity, alcohol consumption and depressive episode). In Browns, racial discrimination was not an independent predictor of weight gain and BMI over time.

Conclusion Weight and BMI gains were observed among all race/skin color groups examined, with no statistical differences between them. The results indicate that Black individuals who reported racial discrimination had greater weight and BMI increases in the study period than those who did not, reinforcing the importance of public policies against racial discrimination to reduce racial disparities in health.