Background: Increases in population waist circumference (WC) are happening at a different speed than body mass index (BMI). Assessing recent trends in WC and BMI gives us a better glimpse of how fat distribution has varied in and across populations and allows a better prediction of obesity associated-diseases. We investigated the changes in WC relative to BMI in five countries and assessed whether any secular changes in mean WC occurred independently of BMI. Methods: We used adult data from 1997 to 2020 from the US, England, Chile, Mexico and Peru nationally representative surveys. Sex-specific country-stratified (for the US, also race-/ethnicity) regressions were used to estimate the annual change in mean WC relative to BMI level, adjusting for age and survey year. We also tested interactions between BMI and survey year. Results: We observed increases in predicted mean WC for a given BMI level across countries except for Peru and USA-Non-Hispanic Black and USA-Mexican American populations. Overall results showed that mean WC among females increased more than males. Among females, mean WC increased more over time only at higher levels of BMI. The largest annual increase in WC was found in USA-Non-Hispanic White females (0.27cm/year, 95% CI 0.18, 0.36) with the largest reduction observed for Peru females (-0.27cm/year, 95% CI -0.46, -0.07) at BMI 35kg/m2. In contrast, males showed a more stable annual change in WC independently of BMI. Only significant increases were observed for Mexico and England males with the higher annual mean change observed for Mexico males at a BMI of 35 kg/m2 (0.14cm/year, 95% CI 0.08, 0.20). The largest reduction in WC was observed for Peru males (-0.47cm/year, 95% CI -0.76, -0.17) at that same BMI level. Conclusions: Over the last two decades, we observed across countries that secular increases in mean WC have been larger in females than males. These changes have largely occurred independently of the level of BMI. These differences bring a significant increase in disparities in abdominal obesity-associated diseases.