Body Mass Index vs. Body Fat Percentage
Obesity in America has become a well-recognized epidemic. The Centre for Disease Control estimates that 35 percent of American adults and 17 percent of American children are obese. However, according to a New York University School of Medicine study, that number is likely much higher.
The CDC bases its obesity rate on the Body Mass Index (BMI). BMI is calculated using only a person’s height and weight and is a very general estimate of body fat.
And using BMI as the sole indicator of obesity may be missing nearly 40 percent of obesity cases, says the NYU School of Medicine study.
The study used BMI and two other types of obesity testing to measure body fat in the participants. The researchers found that BMI underestimated the subject’s body fat by an average of 4%, and the number of missed obesity diagnoses jumped significantly in older women who may not have gained any weight but had lost muscle mass with age.
“Studies like these continually show that testing for BMI or weight is not a sufficient indicator of good health or optimum weight,” said Neil Wolkodoff, Ph.D. and Director of the Denver Center for Health and Sports Sciences (DCHSS). “People may fall in the normal BMI range but are unhealthy because they have too much body fat and not enough muscle mass.”
Indeed, the researchers also warn of the future dangers for people who mistakenly think they fall into the average ranges. They say that patients are misinformed that they are fit and thin, and then they bump into heart attacks and diabetes as they age. If they were made aware of their issues when they were young, they would proactively make diet and exercise changes to get to healthier levels.
“BMI also doesn’t tell you how your weight is distributed,” says Wolkodoff. “A person might fall into the normal range but have a lot of visceral fat, which is the more dangerous type of fat from a health perspective. The more visceral fat there is around the central organs, the higher the stress on the body.”
Advocates for using BMI testing for obesity screening say that cost and ease of use (it’s free, and you only need to know your height and weight to do it) are two of the reasons it should continue to be used.
However, there are various other more accurate body composition tests available, and one of the newest technologies is accessible at the Denver Center for Health and Sports Sciences.
InBody720 Testing Machine
Last August, DCHSS was the first in Colorado to unveil the InBody720 Body Composition machine. In less than two minutes, the InBody720 offers high-precision measurements of weight, lean body mass by segment, body fat mass, total body water, BMI, and Basal Metabolic Rate comprehensive picture of patient’s health, optimal weight, and specific exercise needs. Additionally, this technology has been scientifically verified to be just as accurate as a DEXA scan or underwater weighing.
“BMI can be a useful initial screening, yet without knowing muscular mass levels, it is almost impossible to determine what type of exercise program will improve a patient’s profile for maximum results,” Wolkodoff added. “The test is also valuable in that it measures how effective someone’s exercise program is at not only maintaining an ideal weight but moreover how effective the program is at maintaining muscle mass and metabolism, both of which decline with age without proper training.”
