What is the Connection Between Obesity and Hypertension?

Hypertension, or high blood pressure, is one of many diseases known to be more prevalent among people who are obese. Approximately two-thirds of all obese people either have hypertension or are at risk for developing it. While medical researchers haven't yet been able to identify the specific cause-effect relationship of obesity and hypertension, they do not doubt that there is one. Suspected culprits include hormonal disruptions and a narrowing of the arteries related to type 2 diabetes in the obese.

Experts define obesity by body mass index (BMI). To calculate BMI, one divides a person's weight by the square of his height, in units of kilograms and meters, respectively. A BMI higher than 30 is considered obese. A person is diagnosed with hypertension when his blood pressure reading is greater than 140 over 90 mmHG.

The location of body fat on obese people determines their risk for hypertension. Apple-shaped people, those with body fat primarily situated around their middle, are at greater risk for developing hypertension, as well as type 2 diabetes, and heart disease. The risk for hypertension is slightly less for pear-shaped people who carry their weight lower, on the hips.

In obese people, hormone levels are often disrupted in the renin-angiotensin-aldosterone system. This hormonal system helps to control kidney function and sodium and potassium regulation, which act to control blood pressure. Medical researchers suspect that disruption of the renin-angiotensin-aldosterone system in obese people more than likely accounts for the hypertensive increase in blood pressure and may explain the high correlation between obesity and hypertension.

Obesity and hypertension can impact the entire body. Carrying excess weight and having elevated blood pressure can damage blood vessels and organs, resulting in impaired function. The organs most typically impacted are the heart and kidneys.

In blood vessels, blood clotting is necessary to repair normal wear and tear. The maintenance of this healthy clotting is referred to as vascular homeostasis. Vascular homeostasis is maintained primarily by the cells lining the blood vessels. Hypertension places greater stress on these cells, damaging them and impairing their ability to maintain vascular homeostasis. The result may be thrombosis, or undesirable clotting, which restricts the flow of blood and may lead to a stroke.

Blood vessel damage caused by hypertension is often most acute in the kidneys of obese people. The kidneys remove waste from the blood and, when the blood vessels in the kidney are impaired, filtration of the waste is decreased. The resulting excess fluid can further increase blood pressure, which then may permanently damage the kidneys.

Obesity and hypertension can also stress the heart. When blood pressure is elevated, the heart has to work harder than normal against this increased force. The result is often an enlargement and hardening of the heart’s left ventricle, and an increased risk of heart attack.

Obese people also often suffer from type 2 diabetes. In type 2 diabetes, the body produces an insufficient amount of insulin or the insulin produced is not utilized by the body. This causes glucose to remain in the blood rather than go into the cells as it should. Elevated glucose levels in the blood can cause narrowing of the arteries, or atherosclerosis. Atherosclerosis increases blood pressure, leading to hypertension.