Longitudinal impact of weight change on blood pressure in University students.

Obesity-related hypertension is increasing in Japan, but limited evidence exists on how weight change in early adulthood affects blood pressure (BP). We aimed to investigate the longitudinal relationship between weight change and BP among Japanese university students. We analyzed data from 20,929 first-year students who underwent annual health checkups at Keio University from 2013 to 2016 and again three years later. Students were categorized into seven groups by percentage weight change. Associations between weight change and changes in systolic and diastolic BP (ΔSBP/ΔDBP) were examined using sex-stratified analyses and restricted cubic spline (RCS) models. Weight gain was linked to BP increases, while weight loss was associated with BP reductions. In men, weight gain >3% increased SBP and DBP, and weight loss >3% reduced SBP; DBP reduction was evident with >10% weight loss. In women, SBP increased with weight gain >5%, and DBP increased with >10% weight gain; SBP decreased with >10% weight loss. RCS models revealed nonlinear, dose-dependent associations with sex-specific patterns. Absolute BMI was also positively associated with BP, with inflection points consistently observed at BMI 21.6 kg/m² for SBP and DBP in women, and for DBP in men. Even moderate weight changes over three years significantly influenced BP, with SBP being more responsive than DBP and stronger effects observed in men. These findings suggest that even during shorter periods in young adults, body weight change has a high impact on BP and highlight the potential public health benefits of strategies aimed at preventing weight gain throughout adulthood. This study examined the longitudinal impact of weight change on blood pressure in university students in Japan. Weight gain increased ΔSBP and ΔDBP, while weight loss decreased them. Effects were stronger for SBP and more pronounced in men. Even during shorter periods in young adults, body weight change has a high impact on BP.