Overweight Boys and Blood Pressure

Heavy adolescent boys are prone to a greater increase in blood pressure under stress and take longer to return to normal pressure levels once relaxed, suggests a study published recently in Hypertension. Blood pressure changes in heavier girls, however, did not increase the risk of blood pressure problems in response to stress.

For the study, the research team measured blood pressure changes in 151 boys and 141 girls of different weights between the ages of 15 and 18. To determine blood pressure responses to stress, the participants played a video game with money at stake for 1 hour. In addition, to having a higher increase and a slower decrease in blood pressure under stress, the boys who weighed more also tended to rid their bodies of less salt, compared with boys who weighed less. When blood pressure increases due to stress, the kidneys respond by increasing output in order to get rid of excess salt. The salt brings excess fluid, thereby decreasing the amount of fluid in the blood, and lowering the blood pressure, said study author Gregory A. Harshfield, PhD.

It is a different story with females. Girls who were heavier were just as able to excrete salt after a spike in blood pressure as normal weight girls, noted Dr.Harshfield. He suggested that the reason may involve estrogen, which dulls the effects of stress hormones and elevates levels of substances that open up blood vessels.