We did a prospective study to investigate whether clinic heart rate (HR) and 24-h ambulatory HR were independent predictors of subsequent increase in body weight (BW) in young subjects screened for stage 1 hypertension. The study was conducted in 1,008 subjects from the Hypertension and Ambulatory Recording Venetia Study (HARVEST) followed for an average of 7 years. Ambulatory HR was obtained in 701 subjects. Data were adjusted for lifestyle factors and several confounders. During the follow-up BW increased by 2.1 ± 7.2 kg in the whole cohort. Both baseline clinic HR (P = 0.007) and 24-h HR (P = 0.013) were independent predictors of BMI at study end. In addition, changes in HR during the follow-up either measured in the clinic (P = 0.036) or with 24-h recording (P = 0.009) were independent associates of final BMI. In a multivariable Cox regression, baseline BMI (P < 0.001), male gender (P < 0.001), systolic blood pressure (BP) (P = 0.01), baseline clinic HR (P = 0.02), and follow-up changes in clinic HR (P < 0.001) were independent predictors of overweight (Ov) or obesity (Ob) at the end of the follow-up. Follow-up changes in ambulatory HR (P = 0.01) were also independent predictors of Ov or Ob. However, when both clinic and ambulatory HRs were included in the same Cox model, only baseline clinic HR and its change during the follow-up were independent predictors of outcome. In conclusion, baseline clinic HR and HR changes during the follow-up are independent predictors of BW gain in young persons screened for stage 1 hypertension suggesting that sympathetic nervous system activity may play a role in the development of Ob in hypertension.