A new article, published in Science Magazine, discusses the use of body mass index (BMI) as a measure of healthy weight.  Obesity has established medical evidence indicating its health detriments.  However, there are some studies that indicate that obesity as defined by BMI actually improves survival rates under certain circumstances.  The article explores how there is controversy around the use of BMI to define obesity.

In an analysis of the article published on the Live Science website, the issue with BMI is explored in greater detail.  BMI is weight in kilograms divided by height in meters squared.  A BMI of 25 to 29.9 is considered overweight and a BMI over 30 is considered obese.  However, BMI does not look at fat versus muscle, nor does it consider the distribution of fat in the body.  Muscle can increase weight, pushing BMI higher without the person being unhealthy.  Also, the location of fat is an important indicator of health risks.

A study published in the American Journal of Clinical Nutrition examined the use of BMI, waist circumference, and waist-to-hip ratio to determine which ones were accurate predictors of health risks.  This study focused on the risk of type 2 diabetes as a result of obesity.  Studying approximately 3,000 men and 3,000 women, the researchers found that using overall adiposity in the body or abdominal adiposity had the strongest relationship with type 2 diabetes development.  The researchers concluded that using BMI alone was insufficient and waist circumference should be incorporated to get an accurate perspective on health risk.

Obesity is a growing problem in the U.S., reports the Centers for Disease Control and Prevention (CDC).  Current CDC statistics indicate that more than one-third of American adults are clinically obese.  Obesity has been associated, for example, with increased risks for diabetes, heart disease, and death.  Consequently, obesity is economically burdensome.  The CDC estimates that the medical costs associated with obesity and related medical conditions are around $147 billion.  As a point of comparison, an obese person will take on medical costs that are, on average, $1,429 greater than someone with a normal weight.  However, obesity rates vary from state to state, with Mississippi having the highest rate at 34.9 percent and Colorado at the low end with 20.7 percent.

LiveScience also points out that criticism of BMI stems from studies that show that obese individuals actually have better mortality rates in cases of heart failure, kidney failure, and other chronic diseases.  Using other measures may more accurately capture the relationship between weight, fat, and health.