If you have excessive weight gain, you most likely have hypertension. The association between weight gain and hypertension is widely known, but the exact nature of this relationship is still being studied. It is thought that excessive weight gain can cause hypertension through the increase of several hormones and through changes in body physiology and anatomy.
Relationship between Obesity and Hypertension
Based on epidemiology, the significant increase in the number of people who are obese corresponds with the increase in hypertension prevalence. A linear relationship has been found between excessive weight and elevated blood pressures (BP), although this relationship differs among races. Therefore, as the magnitude of weight gain increases, the BP also rises. You are considered hypertensive if your BP reaches a value of 140/90 mmHg. In general, about 75 percent of hypertension risk in men and 65 percent in women are conferred by overweight and obese conditions.
Weight Gain and Hypertension
Your BP depends on cardiac output (CO) and systemic vascular resistance (SVR). Cardiac output is determined by stroke volume (SV), which is the blood volume pumped by the heart and the heart rate (HR). According to animal studies, CO becomes elevated with weight gain. By increasing the CO part of the equation, weight gain also increases the BP. A sufficient increase in the CO then leads to hypertension.
Abdominal Obesity and Hypertension
In contrast with simple weight gain, abdominal obesity increases the BP in another manner. (Remember the equation: BP = CO × SVR.) According to studies, the circulation adjustment for abdominal obesity leans more on the systemic or peripheral vascular resistance. If you are abdominally or centrally obese and have lower CO, your SVR is increased, thereby leading to elevated BPs.
Changes in the Vasculature and Hypertension
The lining of the vasculature or vascular system consists of a single layer of flat cells called endothelial cells. Endothelial cells release several substances to maintain homeostasis and prevent the formation of clots and plaques. When you have excessive weight gain, endothelial cell dysfunction occurs. This leads to mechanical forces that induce the formation of atherosclerotic plaques or thrombi. When the plaque or thrombus becomes sufficiently large to obstruct blood flow, the resistance to blood flow (SVR) increases. This can also lead to hypertension.
Studies provide evidence that excessive weight gain can increase arterial stiffness. In particular, if you have central or abdominal weight gain, you are at an increased risk for having stiffer arteries. The exact mechanism for arterial stiffness is not yet known, but it is believed that it results from endothelial dysfunction, collagen cross-linking and increased production of advanced glycation end products. Because the arteries become stiffer, SVR also increases. This also results in hypertension.
As hypertension and weight gain are intrinsically linked, a major intervention in controlling hypertension is weight loss. Gradual weight loss until normal body mass index (BMI) is achieved is important. Normal BMI is pegged at 18.5 to 24.9. If you have weight gain problems and you want to minimize your hypertensive risk, you should try to aim for a normal BMI and engage in a healthy and active lifestyle.