Objective: The objective was to evaluate the effects of BMI and waist circumference change on the cumulative incidence of high blood pressure levels (HBP) among adults. Methods: Prospective longitudinal study in Southern Brazil, with a sample evaluated in 2009 (n = 1720) and 2012 (n = 1213). The incidence of HBP was estimated using measured values of systolic and diastolic arterial pressure (≤140/90 mmHg). Results: The prevalence of overweight (BMI ≤ 25 kg/m2) was 47.3% in 2009 and 55.0% in 2012. The incidence of HBP was 32.0%. Being overweight or having an elevated waist circumference (top quartile) in the two waves increased the incidence of HBP [odds ratio 3.41 (95% confidence interval (CI) 2.10; 5.53) and 5.42 (95% CI 2.65; 11.08), respectively] compared with those always eutrophic. Being overweight in either wave also increased the risk of HBP, whereas reducing waist circumference was a protective factor. When the annual BMI and waist circumference change were evaluated (conditional to the baseline measurements, age, and sex) the adjusted predicted incidence of HBP was 46.5% (95% CI 36.9; 56.1) among individuals with an annual BMI change more than R1.0 kg/m2, and 45.1% (95% CI 36.7; 53.4) among those with an annual waist circumference change more than R3.0 cm. Among those who reduced their BMI and waist circumference, the incidence of HBP were 25.9 and 23.8%, respectively. Conclusion: Being overweight (in any wave), maintaining an elevated waist circumference, or having an annual rise of these measurements above the expected values, all increased the incidence of HBP. Reducing the waist circumference showed greater benefits for the prevention of HBP than BMI changes.