Defy Gravity

A Wake-Up Call for Americans

Over the past twenty years there has been an increased effort by both the public (government) and private sector to educate Americans on the benefits of pursuing a healthy lifestyle.

Unfortunately, the many interventions designed to encourage better nutrition, regular physical activity, smoking cessation, and to reduce or moderate alcohol consumption may not be having the desired impact.  Moreover, Americans appear to be getting less healthy on the whole.

Researchers at the University of South Carolina compared data collected as part of the National Health and Nutrition Examination Survey (NHANES). The survey evaluated lifestyle based on five factors: physical activity, smoking status, alcohol consumption, Body Mass Index (BMI) and consumption of fruits and vegetables.  Patients at the University Medical Center were surveyed between 1988 and 1994, and again between 2001 and 2006.  All participants were between 40 and 74 years old at the time of the survey.

The troubling news is that patients are entering the hospital with poorer lifestyle habits across all five measured variables than they did more than 18 years ago.  BMI increased by 8% from 28% to 36%.  Participation in physical activities at least 3 times weekly on average is down 10% to 43%.  The same number of adults are smoking, 26.5%, and moderate alcohol intake rose 11% to 51%.  Last, fewer people are eating their fruits and vegetables as 26% currently report eating at least 5-a-day.  That’s down 16%.

Overall, adherence to all 5 measures decreased by nearly half, from 15% to 8%.  Hence, it could be determined from this study that adults are not heeding the advice to improve their lifestyle.  However, this study was limited to patients entering a medical treatment facility.  The results could simply demonstrate that adults with previously poor lifestyle habits are continuing to make poor choices, and the data may not be transferable to the entire population. Regardless, as fitness professionals this information should be interpreted as an opportunity to get out and change more lives, paying special attention to those who have the greatest obstacles to overcome. 
King, D.E. et al (2009) Adherence to healthy lifestyle habits in US adults, 1988-2006. American Journal of Medicine. 122: 528-34.

Is BMI Obsolete?

The Body Mass Index (BMI) is a value placed on the relationship between an individual’s height and weight.  BMI value is based on a simple paradigm with respect to health and risk for disease.  If there are two individuals of equal height and one individual is significantly heavier, the BMI will indicate a greater risk for poor health for the heavier person.

From its inception the Body Mass Index has been questioned in its ability to accurately predict health risks and estimate body fat.  The BMI has numerous flaws.  For one, it fails to account for the lean body mass and fat mass ratios in assessing healthy weight.  The upside to BMI, however, and the primary reason why it remains a mainstream tool for healthcare professionals has everything to do with its simplicity in comparison to other measurements such as body fat testing, or anthropometrics.  There may be a new option on the horizon.

In a study recently published in the journal Pediatrics, researchers from the University of Michigan determined that a child’s neck circumference was equally effective as a predictor of disease in adulthood as the waist measurement and BMI.

Researchers assessed anthropometrics, or body circumferences in more than 1100 children ages 6 to 18.  Neck circumference was determined based on the widest measurements attained at the neck.

Upon review, correlations were found between Neck Circumference and BMI values previously associated with diseases such as obstructive sleep apnea, diabetes, or high blood pressure in adults.

In an interview with the researchers, the authors suggest that one major drawback of using BMI is that it does not address abdominal adiposity directly whereas neck measurements are directly linked to waist measurements.

In addition, the researchers felt that neck measurement would present a more meaningful value to patients compared to the BMI.  They recognize that because the patient does not understand BMI as he/she understands weight or height, the perception of the BMI value is often not sufficiently threatening to instigate behavioral change.

Finally, the reliability of repeat measurements for the neck is greater than the waist measurement, because experts continue to disagree on the best point to record the waist measurement.  For example, ACSM uses the smallest measure between the sternum and the navel, however, that value can often be deceptive if the individual carries most of his/her abdominal fat below the navel.

This is an original study.  Hence, neck circumference and risk stratification charts are not currently available.  However, you should expect to see these become available in the near future.  In the meantime, rely on direct measurements of body fat along with anthropometric measurements to predict health risk in clients.
Madison Park. Can Neck Measurement Indicate Body Fat Better than BMI? CNN.com July 6, 2010.