Increases in weight and body size increase the odds for hypertension during 7 years of follow-up.

Changes in BMI and body size were compared to incident hypertension in 24,550 men and 10,111 women followed prospectively as part of the National Runners' Health Study to test whether long-term weight change affects hypertension risk. Incident hypertensions were reported by 2,143 men and 430 women during (mean +/- s.d.) 7.8 +/- 1.8 and 7.5 +/- 2.0 years of follow-up, respectively. Despite being active, men's and women's BMI increased 1.15 +/- 1.70 and 0.95 +/- 1.89 kg/m(2), respectively, and their waist circumferences increased 2.97 +/- 5.02 and 3.29 +/- 6.67 cm, respectively. Compared to those whose BMI declined, those who gained >or=2.4 kg/m(2) had an odds ratio (95% confidence interval) of 1.68 (1.45, 1.94) for becoming hypertensive if male and 1.42 (1.05, 1.92) if female. Men whose waist circumference increased >or=6 cm had an odds ratio of 1.22 (1.01, 1.47) for becoming hypertensive compared to those whose waists decreased. In both sexes, the odds for hypertension were significantly related to BMI at follow-up when adjusted for baseline BMI, but generally not to baseline BMI when adjusted for follow-up BMI. In the subset whose weights remained relatively unchanged during follow-up (+/-0.4 kg/m(2)), each kg/m(2) increment in BMI was associated with an odds ratio for becoming hypertensive of 1.19 (1.14, 1.24) in men and 1.11 (1.02, 1.20) in women. Thus, even among lean, physically active individuals: (i) weight gain increases hypertension risk; (ii) higher body weight increases the hypertension risk in a dose-dependent manner in the absence of any weight change; and (iii) there is no advantage carried forward to having been previously lean.