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Comparison of a 2D iPad application and 3D body scanner to air displacement plethysmography for measurement of body fat percentage
- Wagner, D. R., Castañeda, F., Bohman, B., Sterr, W.
- Journal of human nutrition and dietetics 2019 v.32 no.6 pp. 781-788
- adults, body fat, body mass index, densitometry, females, image analysis, males, scanners, scanning electron microscopy
- BACKGROUND: Novel and innovative imaging methods that rapidly estimate body fat percentage (%BF) are publicly available, yet little is known about their accuracy. The present study evaluated the test–retest reliability of a two‐dimensional iPad (Apple, Inc., Cupertino, CA, USA) application (2D APP) and a three‐dimensional body scanner (3D SCAN) for estimating %BF and compared both imaging methods with air displacement plethysmography (Bod Pod; Cosmed USA, Inc., Concord, CA, USA). METHODS: Seventy‐nine adults (37 female, 42 male) varying widely in age [mean (SD), range] [32.9 (12.4), 18–65 years] and body mass index [25.0 (4.9), 18.2–41.8 kg m–²] were measured with the Bod Pod and twice with the 3D SCAN and the 2D APP in a repeated‐measures design. RESULTS: Test–retest reliability was excellent for both the 2D APP (intraclass correlation = 0.993) and the 3D SCAN (intraclass correlation = 0.993) with the SEM <1% BF for both methods. Although the three methods were highly correlated with each other (r = 0.857–0.923), the mean %BF estimations were significantly different (P = 0.001). The 2D APP [19.9 (8.2)%BF] underestimated the Bod Pod value [21.9 (9.4)%BF] and the 3D SCAN [24.0 (6.8)%BF] overestimated. Additionally, the SE of estimate and total error exceeded 4% BF for both 2D APP and 3D SCAN, and both methods tended to overestimate lean participants and underestimate fat participants. CONCLUSIONS: Although highly reliable, neither the 2D APP, nor the 3D SCAN provided valid estimates of %BFBₒd Pₒd.