OBJECTIVE:To examine the impact of overweight and obesity on development of target organ damage in the early stage of hypertension.SUBJECTS:Participants were 727 young-to-middle-age subjects screened for stage 1 hypertension and followed for 8 years.MEASUREMENTS:Ambulatory blood pressure (BP), albumin excretion rate and echocardiographic data were obtained at entry, every 5 years and/or before starting antihypertensive treatment.RESULTS:During the follow-up, hypertension needing treatment was developed by 54.7% of the subjects with normal weight, 66.6% of those with overweight and 73.0% of those with obesity (P<0.001). Kaplan-Meier curves showed that patients with obesity or overweight progressed to sustained hypertension earlier than those with normal weight (P<0.001). At study end, rate of organ damage was 10.7% in the normal weight, 16.4% in the overweight and 30.1% in the obese subjects (P<0.001). In a multivariable logistic regression analysis, overweight (P=0.008) and obesity (P<0.001) were significant predictors of final organ damage. Inclusion of changes in 24-h BP and body mass index, and of baseline organ damage did not virtually modify these associations (P=0.002 and <0.001, respectively). Obesity was a significant predictor of both left ventricular hypertrophy (P<0.001) and microalbuminuria (P=0.015) with an odds ratio (95% confidence interval) of 8.5 (2.7-26.8) and 3.5 (1.3-9.6), respectively.CONCLUSION:These data indicate that in hypertensive subjects obesity has deleterious effects on the cardiovascular system already at an early age. Preventive strategies addressed to achieve weight reduction should be implemented at a very early stage in young people with excess adiposity and high BP.International Journal of Obesity advance online publication, 6 March 2012; doi:10.1038/ijo.2012.32.