When we talk about obesity, we often speak of it in terms of body mass index – or BMI – which is a measure of “body fatness” that is calculated using height and weight. BMI is inexpensive to obtain and relatively simple to use, so it’s easy to see why it has become our main measure of obesity. However, experts believe that other measures may be better at calculating the health risks of obesity.
For instance, in a recent study, researchers found that visceral adipose tissue (the fat that accumulates deep in the stomach around the organs), rather than BMI or overall fat, was associated with the development of hypertension. The study sought to address the question: why is hypertension clearly linked with obesity, but not all obese people develop high blood pressure? Researchers examined data on more than 900 people for the development of hypertension, in order to determine the relationship of fat distribution with incident of the condition.
During the 7 years of the study, 230 participants were diagnosed with hypertension. Those who became hypertensive were older, more commonly had already developed diabetes (7% versus 2%) and more often were black (56% versus 33%). They also had higher BMIs and had more subcutaneous fat and visceral adipose tissue. From their analysis, the researchers found that increased visceral fat was significantly associated with incident hypertension. It was a better indicator than either BMI or subcutaneous fat.
“This is an interesting study, said Gerardo Cárcamo, MD, expert bariatric surgeon in San Antonio. “The ability to reliably predict who is at higher risk of hypertension is a great tool. It could lead to earlier diagnosis of hypertension in patients and hopefully help prevent hypertension from ever developing in the first place,” Dr. Cárcamo said.
Another recent study in children echoed the relationship between body fat and hypertension. These researchers looked at children ages 7 to 14 and incidence of hypertension or prehypertension. They related that to body weight and especially to body fat, and were able to show in this rather alarming study that there was a very clear relation where the risk of being hypertensive almost tripled. These studies prompt questions to whether BMI is the best indicator of the health risks of carrying excess weight, and whether other measurements should be routinely used, despite being more costly or difficult to obtain.