Moving Beyond BMI
OPT for Health director and associate director Drs. Jessica LaRose and Autumn Lanoye attended the 47th annual meeting of the Society of Behavioral Medicine in Chicago, IL April 22nd-25th.
Dr. Lanoye presented a research spotlight entitled “Moving Beyond BMI: Waist Circumference and Body Fat as Risk Indicators in Behavioral Obesity Treatment,” co-authored by Drs. Karly Casanave-Phillips, Chloé Jones, and Jessica LaRose.
Paper summary:
An article published last year found that among younger adults (age 18-40), cardiometabolic disease risk classifications based on body fat percentage and waist circumference were associated with 15-year all-cause and heart disease mortality, while those based on body mass index (BMI) were not. This prompted us to explore data from our own previously-completed REACH Trial of behavioral weight loss for emerging adults age 18-25, which measured body fat percentage, waist circumference, and BMI. Our goal was to examine patterns of risk based on these three measurements in order to 1) identify areas of overlap/divergence and 2) characterize change over time.
At baseline, we found:
- 41.7% of participants were at risk for cardiometabolic disease based on BMI, body fat percentage, and waist circumference
- 32.7% were at risk for cardiometabolic disease based on BMI and waist circumference
- 1.8% were at risk for cardiometabolic disease based on BMI and body fat percentage
- 18.3% were at risk for cardiometabolic disease based on BMI alone
Of those who returned for their follow-up assessment after the 6-month intervention, the majority of participants (63.1%) remained in the same risk category they began in. However, 33.0% had an improved risk profile (ex., at risk based on BMI and waist circumference at baseline but at risk based on BMI only at follow-up) and 3.9% had a worsened risk profile (ex., at risk based on BMI and waist circumference at baseline but at risk based on BMI, waist circumference, and body fat percentage at follow-up). Among participants who lost a clinically significant amount of weight (>5% of their baseline weight), there was substantial variability with respect to magnitude of change in waist circumference and body fat percentage.
Our Takeaways:
- In the context of behavioral interventions, BMI-based eligibility criteria may result in overlooking young adults who are at risk of cardiometabolic disease based on waist circumference and/or body fat percentage but have a BMI < 25kg/m2.
- A focus on weight loss alone does not provide the full picture in terms of risk reduction, but there are no clinically significant change thresholds for waist circumference and/or body fat percentage. These need to be established—especially for young and racially/ethnically diverse populations.
- Weight and BMI continue to be used even though they are imperfect because they are easily measurable, while things like waist circumference and body fat percentage require training and/or specialized equipment to measure. Additional work is needed to improve individuals’ access to these and other metrics that more accurately indicate risk for developing cardiometabolic disease.