How Doctors Actually Diagnose Obesity

The obesity crisis in America is a hotly debated topic. According to the Centers for Disease Control and Prevention, more than 35% of adults in the U.S. are considered to be obese, and this disease can lead to chronic health problems such as diabetes. The need for new ways to fight this disease has led VIVUS (VVUS), Arena Pharmaceuticals (ARNA), and Orexigen Therapeutics (NASDAQ: OREX) to develop medications for the treatment of obesity. VIVUS' drug Qsymia is already on the U.S. market, though sales have not impressed investors so far, Arena is nearing the launch of its medicine Belviq, and Orexigen's drug is in late-stage clinical trials.

As investors assess the merits of each stock, many may not fully understand the complexities of treating this disease. For instance, what role do drugs actually play in treatment? Are lifestyle changes more important? Is obesity even considered to be a disease?

To help demistify these topics, Motley Fool health care analyst Max Macaluso spoke with Dr. Domenica Rubino, a weight-management expert and representative of The Obesity Society. In the following segment from their discussion, Dr. Rubino discusses how physicians actually diagnose obesity. A transcript follows the video.

The relevant video segment can be found between 3:03 and 5:18.

Max Macaluso: As a doctor, how do you go about diagnosing obesity?

Dr. Domenica Rubino: In terms of diagnosis the first thing really is the basic thing that everyone talks about -- which is probably the most complicated for the average person to understand -- is the BMI, the body mass index, which is just a way of looking at your weight, how it's related to your height.

We do know that higher BMIs -- BMIs greater than 25, and especially BMIs greater than 30 -- are associated with increased risk of heart disease and comorbidities.

The difficulty with BMI is I think your average person doesn't really relate to it very well. It's also complicated that it is affected by age, affected by gender, and also affected by extreme differences in height.

Someone who's very tall will have a much higher BMI, or someone who's very short... it's hard to actually get a good assessment of what does that mean in terms of actual fat.

Macaluso: For instance, if you're a body builder you could have a BMI well above 30, but you may not be obese.

Rubino: Exactly. Although I would say people would argue, once your BMI hits 30 you can't really say it's because of athleticism and probably you have some excess fat, but it may not be such a good correlation for if you had a BMI of 27 or something like that.

We look at waist circumference, and I think most people can relate to waist circumference. We all know when our clothes are getting too tight. For women, a waist circumference greater than 35" and men greater than 40", there's a definite increase in risk of developing both diabetes and heart disease.

Waist circumference has been shown to relate to these, but it's something we can identify with. As a field, we're starting to look at that. We know if you have a certain BMI and you have a certain waist circumference, your risk is much higher.

Now we're trying to really stratify, how is someone really at risk?

They may be at risk metabolically. They may have these conditions that we talked about, like diabetes or high blood pressure. They also may be at risk because their weight is also affecting their mood. They may be depressed or anxious, but it's also affecting their function, their mobility. They're not able to walk; they're feeling short of breath.

We're trying now to get a better assessment of what are the patients who are at the most risk, versus those who might be 40 pounds overweight but actually not have any of those problems. We're trying to sort through that right now.