Comparative assessment of change in fat mass using dual X‐ray absorptiometry and air‐displacement plethysmography

Abstract

Objective To compare the accuracy of body composition measurements to small, defined changes in fat mass between dual X-ray absorptiometry (DXA) and air-displacement plethysmography (ADP). Methods Fifty-six healthy adults, 29 women and 27 men (age, 38 ± 12.4 years; BMI, 27.6 ± 5.8 kg/m2) were included in the study. Exclusion criteria were pregnancy, indwelling metal hardware or pacemakers, or weight exceeding DXA table limit (>350 lbs). All individual testing was completed within a 2-hour period. Fat packets were prepared using lard wrapped in plastic and applied exogenously in defined locations. Each participant completed body composition measurements with ADP and DXA (both testing modalities completed with and without 1 kg of exogenously applied fat mass). Results Both DXA and ADP were highly accurate in detecting an overall increase in body mass associated with exogenously applied 1kg of fat mass (0.99 kg vs. 0.97 kg, respectively). DXA more accurately detected exogenous fat increase as fat mass compared to ADP (0.93 kg; 90% CI for the mean of the difference: 0.83 to 1.03 kg vs. 0.45 kg; 90% CI: 0.19 to 0.71 kg, respectively). The accuracy of body mass detection was similar for males and females (0.97 vs. 1.02 for DXA and 0.92 vs. 1.02 for ADP, respectively), though accuracy in detecting added mass as fat was less accurate in males than females (0.84 vs. 1.00 for DXA and 0.39 vs. 0.51 for ADP, respectively) Discussion Both DXA and ADP are accurate in detecting an overall increase in body mass associated with exogenously applied 1kg of fat mass. However, DXA is more accurate than ADP in correctly identifying the increase in body mass as fat mass, as opposed to fat free mass.

Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta‐analysis

“…Studies included in the meta‐analysis used different methods as reference standard to assess body composition. Based on comparable accuracy, studies that used DXA, HW, ADP and isotope dilution measurement of total body water were grouped together and the pooled estimates were reported and compared with those studies that used lower accuracy measures as the reference standard method (BIA and skin‐fold) . For studies reporting diagnostic accuracy of BMI when compared with more than one BF composition measure, data from the higher accuracy BF composition method were used in overall pooled analysis.…”

Diagnostic performance of mid-upper arm circumference to identify overweight and obesity in children and adolescents: a protocol for a systematic review and meta-analysis

“…Reference standards based on relatively equivalent diagnostic performance comparable accuracy, studies that used dualenergy X-ray absorptiometry, hydrodensitometry and air displacement plethysmography will be grouped together and the pooled estimates will be reported and compared with those studies that used lower accuracy measures as the reference standard method (bioelectrical impedance, skinfold thickness and BMI). [30][31][32] Assessment of publication bias To assess possible publication bias, we will use Deeks' funnel plot, with Deeks' asymmetry test, where p<0.05 will be considered as significant asymmetry. 33…”

The role of stem cells in adipose tissue remodeling.

“…More recently, these cells have been called "beige" adipocytes. These cells have a lineage consistent with that of white adipocytes but express UCP-1 and generate heat upon stimulation (17,(23)(24)(25)(26).…”

“…For this, the subject undergoes a fairly standard X-ray procedure and the bone, fat, and lean mass can be calculated based upon the absorption of x-rays in each tissue type (26).…”