Changes of body mass index among young men in Brazil over two decades

To evaluate changes in the body mass index (BMI) of young Brazilian men in two regions of Brazil at opposing socioeconomic extremes in order to determine whether the changes in BMI distribution had different patterns over two decades.

We selected a sample of 6,706,386 males as the study population, aged 18 years, from individuals that were conscripted into the army from 1980 to 2005. The percentiles of the BMI distribution from 1980 to 2005 were calculated. For each percentile, the slope of a linear regression curve was tested for increases or decreases over time (p < 0.05).

The secular trends in BMI showed the largest increases at the upper ends of the distributions. However, the lower values of the percentiles in both regions did not change over time. The 10th percentile for the southeast region and the 20th percentile in the northeast did not change.

No significant differences in the lower percentile values were found for the BMI distribution of young Brazilian males during the period 1980-2005, suggesting that around 10% of young Brazilian males living in the most developed regions, such as the southeast, are protected against obesity.