Dear DOCTOR Owen:

I have read that the latest and the greatest measurement of obesity is the waist-to-hip ratio. I thought Body Mass Index (BMI) was the benchmark that agencies are using now to measure obesity. Why the change and what does this ratio mean?

Waist/Hip Conscious

Dear “Conscious”:

I can see that you are an avid reader. Obesity measurements are an evasive target because the “fatness,” or the size, of a person only predicts risk of disease. In addition, someone may think that he’s obese at 10 pounds overweight and stresses over this issue. On the other hand, someone else may be 100 pounds overweight and feels just fine. Who is fat? Both of them? The answer, which is relative, depends on whom you ask!

Scientists have long been trying to pin risk on obesity. Certainly, we know that most chronic diseases increase with obesity. But then comedian Dave Letterman, who is rail thin and jogs 5 miles/day, had a quintuple coronary bypass. And, I have many very obese patients who have absolutely clean coronary arteries. So, there is no way to consistently measure risk or obesity in an individual case. The following measurements predict risk of disease:

1. Body Mass Index (BMI) was adopted on the demise of the old Metropolitan Life Insurance. Tables. According to those life insurance measurements, almost everyone in recent years more than had a high-risk profile, so life insurance companies could not insure anyone. BMI is associated with risk of disease—especially cardiovascular (cholesterol, diabetes, and hypertension). As with Mr. Letterman, BMI only applies to groups of people, not individuals. BMI is a convenient way to “slot” someone into a category, raise suspicion, and perhaps indicate the need for testing for certain disease. It does not define obesity per se—only risk.
2.  Waist-to-Hip ratio (W:H) is a more accurate predictor of risk. The larger the belly in relation to the hips, the greater the cardiovascular risk. Because W:H cannot stratify large groups of people, it has not replaced BMI by agencies or insurance groups. People who have been fat most of their lives generally have the weight distributed all over their bodies. Those with primarily abdominal fat usually acquire it in adulthood. This is associated with high insulin levels, which raise cholesterol, blood pressure, and blood sugar.
3. I frequently am asked to define obesity, but my answer is always relative to. . . what? People from Africa think Americans are obese. African Americans recognize obesity differently than European Americans. Nordic Americans view obesity differently than Mediterranean Americans. Physicians view obesity differently than laypersons. I can state unequivocally that great differences of opinion also exist among physicians about when and how to treat obesity.

I always consider the following after evaluating, first, a patient’s health problems and then whether weight is a health risk:

• Someone with high cholesterol—obese or not—is at higher risk for heart disease than the person with low cholesterol. (I would never assume that diet or weight loss would eliminate that risk.)
• Most sleep apnea patients are obese, but will become symptom-free while dieting. Is diet the correct treatment or are C-PAP breathing devices better? Or, should both treatments be applied?
• 93% of Type 2, adult-onset, diabetics will normalize their blood sugar with intense dieting or obesity surgery. Should those treatments be promoted or enforced? Or, should medication be the treatment? (Less than 50% will gain control with medication alone.)

In summary, measurements are tools that give useful information, which can be used in making decisions. Measurements define neither a disease nor a person. The measurement tools above define information that is applicable to groups of people. It is important to use that information: To aid in treatment? To discriminate? To make financial decisions? Professionally, I rarely use the measurements in individual cases.

What is your goal? To look good? To feel good? To live longer? To live better? Measurements are only tools that can be used to help define and achieve those goals.