Researchers studied a population of 28,965 predominantly white women and looked at the risk of developing cancer using body mass index scores (BMI) and waist circumference data and concluded that body shape assessment added no added diagnostic benefit compared to BMI scores. For years research has linked body shape to increased risk of all manner of metabolic disease: heart disease, diabetes, even cancer. This is why most people have heard the line about an apple shape being more problematic than a pear shape. But researchers led by Mia Gaudet, PhD analyzed data from women participating in the Cancer Prevention Study II suggest that assessing body shape doesn’t help. They assert that BMI–a simple calculation relating weight to height– is the risk factor that matters most. I’m not so sure.
A growing body of research criticizes Body Mass Index, a tool commonly used to the assess risk of disease. Without any assessment of body composition, body mass index can’t discriminate between the lean and muscular athlete and a far more metabolically challenged couch potato. If both individuals share the same height and weight, they share the same BMI score. But body composition differences count, and is only one of several reasons I find this study comparing BMI to body shape troubling.
Research shows that when our body gains fat weight, preferentially in deep visceral spaces in the belly, we are often at greater risk of metabolic disease. This pattern of fat gain is driven by our body’s effort to metabolize the food we eat in the most efficient way possible. Most of us are wired to survive. What we eat determines whether our cells preferentially burn the food we eat for fuel or store it as fat. How the body responds depends on a wide range of factors including our sensitivity to insulin, amount of physical activity and level of fitness, as well as our response to sources of stress. So why did these researchers find body shape no more significant than BMI? Maybe the way we measure for an “apple shape” is part of the problem.
HOW DO WE MEASURE AN APPLE SHAPE?
While you may look in the mirror to assess your body shape, your doctor or other health care provider typically measures waist circumference to determine whether a patient is an “apple” or a “pear”. World Health Organization standards state that if a woman’s circumference is greater than 88 cm (approximately 35 inches) she is considered an apple. For a man the cut off point is 102 cm, just over 40 inches.
Researchers debate the validity of these standards since they were originally established in a Dutch population and are best suited for Caucasians. There are numerous efforts all over the globe to establish standards that can more effectively assess people with different ethnic roots. But lack of cultural specificity is only one of the problems here. The measurements still don’t adequately capture people who are at metabolic risk, especially skinny people who sport just a little belly.
I see many clients who never come close to meeting the cut off measures, but they hold weight in their belly. They are relatively thin so no one ever suspects the metabolic risks they live with every day. Even thin people can preferentially store deep visceral fat and a measuring tape is not going to pick it up. This is especially true in older clients or chronic dieters who have already lost a great deal of muscle mass.
The underlying problem draws from a deeply embedded bias known as “weightism”. Weightism assumes people of size are inherently less healthy. Most health professionals and everyone else on the street continue to nurture weight bias based on messy assumptions and every sloppier science. BMI and waist circumference measures attempt to simplify risk assessments for researchers and clinicians alike. We need to remember that these measurements are limited screening tools. They can both over and under estimate risk of disease. Neither BMI or waist circumference scores should be used for diagnostic purposes.
Once the screening process is over, it’s time to use more accurate measures to assess risk. Let’s abandon the less than reliable measures of weight to diagnose health risk and focus on true bio-markers of health. For starters, include measures of inflammation, blood pressure, markers for insulin and blood glucose, as well as problematic lipids in the blood. Include sensitive and more sophisticated assessment of lifestyle factors including diet, activity, and sleep patterns. More thoughtful and careful assessment of true risk is needed. We need to move beyond weightism and start promoting health at every size.