Accuracy of body fat percentage measurements from a smartphone-based 3D application compared to a bioelectrical impedance analyser

Conventional methods of assessing body composition are accurate but may not be accessible beyond clinical settings. While technological advances have led to the development of more convenient alternative measures, their accuracy has yet to be determined. The present investigation assessed the accuracy of a smartphone-based 3D application’s measurements of body fat percentage in comparison to a bioelectrical impedance analyser (BIA), a well-established criterion measure. Sixty-nine apparently healthy, college-aged adults had their body fat percentage measured with BIA followed by the smartphone-based application. Spearman’s rank correlation was calculated to be 0.98 (95% CI: 0.92, 0.99), indicating a very strong correlation between the two BF percentage measures. The bias observed between the two devices was low (0.2% [95% CI: -0.1, 0.5]) with limits of agreement spanning from -2.9% (95% CI: -3.4, -2.3) to 3.2% (95% CI: 2.7, 3.8). Given the strong overall agreement between the two modalities, this smartphone-based application may have the potential to make accurate body fat measurements more accessible. Further validation is needed in more diverse populations and against other criterion measures, such as dual-energy x-ray absorptiometry (DXA).