The number of U.S. citizens with high blood pressure is increasing, mainly due to growing rates of obesity, researchers at the National Heart, Lung and Blood Institute said.

The findings were based on a study conducted by collecting data from an estimated 30,000 people who participated in the National Nealth and Nutrition Examination survey between 1988 to 1994, and for a second time between 1999 and 2004.

High blood pressure, or hypertension, can lead to stroke, heart attack, kidney failure or heart failure. Due to its lack of symptoms, the medical condition is also called the “silent killer.”

As researchers reported, the number of American adults suffering from hypertension increased to 29% over a period of six years ending in 2004. During a previous period, which also lasted 6 years but ended in 1994, only 24% of American adults had high blood pressure.

"The percentage of the population with high blood pressure is going the wrong way - it's increasing," and not decreasing, as it should, according to Dr. Jeffrey Cutler of the NIH's National Heart, Lung, and Blood Institute.

Furthermore, the report also disclosed that another 30 percent of Americans were suffering from prehypertension, a medical condition where an individual’s blood pressure is elevated above normal but not to the level believed to be hypertension.

The risk of high blood pressure is no less than five times higher in obese people, compared to individuals of normal weight. Almost two-thirds of hypertension cases are consequence of extra pounds.