Reference: Amber Wilhoit, RD, LD, NSCA-CPT
While BMI (Body Mass Index) is a good tool in the measurement of body fatness it is not perfect. Measuring the circumference of the waist can provide an additional check. Waist circumference is highly correlated with the amount of fat within the abdomen, or visceral fat, which in many studies is an independent predictor of increased risk for diabetes, hypertension, high cholesterol, and heart disease.
The combination of waist circumference and BMI can be useful in assessing health risk. For example, an elevated BMI with a low waist circumference may indicate that BMI overestimates risk in a particular person, and a low BMI with a high waist circumference may indicate the opposite. The National Institutes of Health Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults proposed that men with a waist circumference greater than 102 cm (40 in) and women with a waist circumference greater than 88 cm (35 in) are at increased risk of metabolic diseases (like those mentioned above).
The distribution of body fat may be put more simply as the apple vs. pear body type. If you tend to store fat around your mid-section, you exhibit the apple body type and are at increased risk for the above mentioned diseases than someone who tends to store fat around their hips, thighs, and buttocks (a pear).
So are you an apple or a pear? While everyone benefits from a better diet and more physical activity, knowing if you are at an even greater risk for chronic disease like diabetes and heart disease can give you even more motivation to change your lifestyle. For those who are pear shaped you do not get a free pass, if you have an increased BMI you are still at risk and making the healthy changes is still beneficial.
Adapted from Modern Nutrition in Health and Disease, Lippincott, Williams, & Wilkins, 10th edition, 2006