Scientists have recently confirmed the efficacy of a new tool—the Body Shape Index—which is reported to predict a person’s obesity-related increase in mortality rate with greater accuracy than the time-old Body Mass Index (BMI). The Body Shape Index (BSI) specifically examines abdominal obesity as a distinguishing risk factor for obese people. The ability to more accurately predict obesity-related increases in mortality using the new Body Shape Index holds promise for both diagnosing at-risk obese persons and providing fresh insight on what it means to be unhealthily overweight.
To date, the Body Mass Index is the tool most commonly used to assess people for obesity. While the BMI is only an indirect method of assessing total body fatness, it is far easier to assess than other, more direct methods of measuring body fat such as underwater weighing, skin-fold thickness measurements, and dual energy x-ray absorptiometry.
However the Body Mass Index is not a perfect tool. Though there is a recognized and strong correlation between body fatness and a person’s calculated BMI number, the two can occasionally produce differing results. In 2005 there was quite a stir when a number of prominent professional football and basketball players were discovered to fall within the “obese” range of the Body Mass Index. Because the BMI does not directly measure fat, it is indeed possible that very muscular and well-conditioned athletes may have seemingly unhealthy BMI scores. The CDC also recognizes that even though the same BMI scoring system is used to assess all adults over the age of 20, there are indeed differences in BMI scores between different genders, races and ages.
Over one third of American adults are now classified as obese. Because of this burgeoning problem, public health experts have been searching for evaluative tools that can easily and cheaply be used to assess the public’s health with greater discernment than the Body Mass Index. One of these efforts has resulted in the creation of the Body Shape Index.
The new Body Shape Index has thus far been reported to predict obesity-related mortality with greater accuracy than the Body Mass Index. This conclusion is the result of a study of over 7,000 adults from Great Britain. These subjects were first examined back in the 1980s and early 1990s, and nearly thirty years later, the researchers looked through records of death certificates to see which subjects had passed away from obesity-related causes. These results confirm those from a similar, albeit shorter study which was conducted in the United States by the National Health and Nutrition Examination Survey (NHANES).
Part of the Body Shape Index’s greater predictive powers with respects to obesity-related mortality rates is due to how it factors in the important variable of abdominal fat. Physicians have known for decades that having larger stomach sizes puts people at risk for premature cardiovascular disease and type 2 diabetes. As opposed to fat that is carried on the hips and thighs in the characteristic “pear shaped body,” visceral fat, or fat that accumulates in the abdominal region, becomes metabolically active, and disposes a person’s body to create more hormones and inflammatory agents. These metabolic products can then lead to higher blood pressure and cholesterol levels.
The Body Shape Index is still in the process of being promoted as a new assessment tool that can easily be used to more accurately identify patients at a high risk for obesity-related diseases and increased mortality rates. Interested individuals can use online calculators to determine their personal BSI score.
By Sarah Takushi