The Relationship Between Hypertension & Body Mass Index

Hypertension, or high blood pressure, affects millions of people in the United States and, according to the American Heart Association, killed more than 56,000 Americans in 2006. A high body mass index has been found to be a factor that puts you at risk of developing hypertension.

Identification

Hypertension is a condition in which the force of the blood against the artery wall is high enough to cause health problems such as heart disease. Readings are reported in a way that indicates both the systolic, or maximum pressure exerted on the artery walls, and diastolic, or minimum pressure exerted on the artery walls. When a doctor tells you your blood pressure is "120 over 80," the 120 is the systolic and the 80 is the diastolic. There are four categories of blood pressure readings: normal, in which the reading is below 120/80; pre-hypertension, which is a reading of 120-139/80-89; stage l hypertension, with a reading of 140-159/90-99; and stage ll hypertension, with readings of 160/100 and above.

BMI

The body mass index, or BMI, is simply a formula that identifies a person's weight relative to his height. A "normal" BMI is 18.5 to 24.9, while a BMI of 30 or above is considered obese. The number doesn't tell the whole story, though. A person who has a normal BMI but has more fat than lean muscle mass could be at risk for some of the conditions related to obesity, while an athlete whose higher BMI is the result of greater muscle mass could be healthy. To date, no research has been done on the specific issue of the healthy athlete with a high BMI and the risk of hypertension.

Hypertension and the BMI

So exactly what is the relationship between BMI and hypertension? Generally, the higher your BMI, the greater your risk of developing hypertension. Researchers have looked at other factors, such as waist-to-hip ratio, age and ethnic background, but in all cases, the BMI was the most important factor. In the Copenhagen General Population Study, researchers found that the systolic blood pressure increased almost four points and the diastolic pressure increased almost two points for each 10 percent increase in BMI.

Considerations

In some groups of people, the impact of body mass index on the risk of developing hypertension might be greater than in other groups. One study compared Asians living in the People's Republic of China, American whites and American blacks. The study found a greater relationship between a high BMI and developing hypertension in the Asian population than in either of the other groups. But the bottom line is that whatever your genetic background, a high BMI increases your risk of developing hypertension.

Warning

While losing weight will decrease your BMI, if you already have high blood pressure or other medical conditions, be sure to consult with your health care practitioner before embarking on a weight loss regime.