From Statistics Canada:
Data from the 2007 to 2009 Canadian Health Measures Survey (CHMS) found that mean systolic blood pressure was significantly higher among boys aged 12 to 19 and girls aged 6 to 11 who were overweight or obese. Mean diastolic blood pressure was significantly higher only among obese boys aged 12 to 19.
Excess weight is believed to influence blood pressure through increased sympathetic nervous system activation, which is associated with systolic blood pressure.
Elevated blood pressure is one of the most important causes of death and disability worldwide, accounting for 7.6 million premature deaths and 92 million disability-adjusted life years annually. Children who have higher blood pressure tend to stay at higher blood pressure levels when they reach adulthood. Hence, high blood pressure in youth may be a risk factor for the development of hypertension in adulthood. This persistence of high blood pressure from younger to older ages is more apparent among overweight and obese youth.