Investigators are using 3-dimensional optical (3-DO) imaging to scan adults and children to better assess body composition and adipose distribution. In 2 posters presented at the 39th Annual Meeting of The Obesity Society (TOS) at ObesityWeek® 2021, 1 team compared the ability of BMI and 3-DO to predict metabolic syndrome in adults. In the second study, 3-DO was used to assess the activity-health relationship in children.
3-DO in Adults
Clinicians usually rely on BMI as a measure of overweight to determine a person’s risk of metabolic syndrome, however, BMI does not take into account the shape of the person. “Body shape provides an indirect measure of body fatness that may improve the identification of metabolic syndrome in adults,” reported lead author of 1 of the studies Jonathan Bennett, a PhD student at Shepherd Research Lab of University of Hawaii Cancer Center, Honolulu, Hawaii.
To study the predictive value of 3-DO in assessing the risk for metabolic syndrome, 501 adults older than 18 years (230 women) were recruited for the Shape Up! Study, metabolic syndrome was diagnosed using the National Cholesterol Education Program (NCEP) guidelines, and body shape was assessed by 3-DO using a Styku S100 scanner.
The authors compared 4 methods to predict metabolic syndrome (MetS– vs MetS+) using BMI; demographic-adjusted BMI; 3DO; and BMI + demographics + 3DO models (Model 4).
A total of 87 patients were determined to be MetS+ using the NCEP criteria. Model 4 had the greatest sensitivity and specificity of the 4 models and predicted 89.7% of MetS+ subjects and 349 of 414 (84.3%) MetS- cases. This model also correctly identified all 7 participants with normal weight MetS+ and correctly predicted MetS- in 90.5% of overweight subjects.
“The 3DO variables included in [Model 4] were, in order of importance: waist to hip ratio, percent bone mass, waist circumference, and calf volume,” the study authors reported.
3-DO in Children
In the second study, 3-DO scanning was used to explore whether the drive to be more active in children is associated with body shape features indicative of health status.
“Two-thirds of children have an implicit preference to be sedentary rather than physically active,” said study author Nicole Fearnbach, PhD, of Pennington Biomedical Research Center of Louisiana State University in Baton Rouge. “These implicit preferences are associated with individual-level markers of health, including cardiorespiratory fitness and whole-body adiposity.”
The study included 101 children (57% girls) with an average age of 13 years and BMI percentile of 72.7. The majority of children (64%) identified as a minority. The children completed the Activity Preference Assessment (APA), which measures the explicit liking and explicit wanting for physical activities (PA) vs sedentary activities (SED). A positive score indicates an implicit activity preference (SED preference) and a negative score indicates a preference for PA.
The Fit3D ProScanner was used to capture variance in 3-D body shape for boys and girls. Linear regression was used to identify principal components (PCs) that were associated with APA bias scores, SED liking, SED wanting, PA liking, and PA wanting and were controlled for age and ethnicity.
Sex-specific associations between APA implicit preferences and body shape as indicated by 3-DO and were found to be stronger in girls than boys. In girls, physical activity preference was associated with leanness (higher values on PC2); whereas in boys, physical activity preference was associated with muscle tone (higher values on PC4).
In addition, leanness in girls was also negatively associated with dual-energy X-ray absorptiometry (DXA) scan and anthropometric markers of adiposity (eg, waist and hip circumference, percent body fat) and markers of glucose metabolism (eg, HbA1c, insulin, HOMA-IR), study authors reported. More muscle tone in boys was also positively associated with grip strength and negatively associated with markers of glucose metabolism and DXA measures of adiposity, reported the authors.
“An underlying implicit preference for PA was associated with leanness in girls and muscle tone in boys,” the study authors concluded. “These PCs are associated with health markers such as total body fat, blood glucose markers, and physical strength.”
Bennett J, EnLiu Y, Kelly N, et al. 3-Dimensional optical imaging body shape improves the prediction of metabolic syndrome over body mass index. Poster presented at: ObesityWeek® 2021; Nov. 1-5, 2021.
Fearnbach N, Wong M, Finlayson G, et al. 3D body shapes associated with children’s implicit preference to be physically active. Poster presented at: ObesityWeek® 2021; Nov. 1-5, 2021.