體脂肪百分比的評量，在健康和運動表現上均是重要的課題，但
測量體脂肪百分比的方法有很多種，且其結果也不盡相同。所以本研
究的目的在以磁共振造影法（MRI）為效標，評估水中稱重法（UWW）
和生物電阻法（BIAt 和 BIAs）測量體脂肪百分比之準確性。
本研究以台灣地區男子12名為受試對象，平均年齡36.4±6.4歲，
平均身高 169.0±5.3 公分，平均體重 67.1±11.2 公斤。受試者分
別接受 MRI、BIAt、BIAs 和 UWW 之測試。所得資料以重複量數單因
子變異數分析進行處理，結果發現：
一、MRI 所測得之體脂肪百分比平均為 18.6±6.7 %。
二、UWW 所測得之體脂肪百分比平均為 15.3±7.2 %，顯著的低於
MRI 所測得體脂肪百分比，相差 18 %。
三、BIAt 和 BIAs所測得之體脂肪百分比平均分別是 22.1±5.7 %
和 25.4±6.0 %，顯著的高於 MRI 所測得的體脂肪百分比，分
別高出 19%和 37 %。
根據結果經過討論可得以下結論：水中稱重法中由密度求體脂肪
百分比之 Siri 公式，和生物電阻法（BIAt 和 BIAs）所使用之製造
廠商預測公式，可能是與MRI結果誤差之所在，所以這些公式均有再
進一步研究甚至修正的必要。

Human body fat assessment is of great importance in health
and athletic performance. However , different body fat assess-
ment methods yield different values for percent body fat.
The purpose of this study was to evaluate the accuracy of
body fat assessment by underwater weighing (UWW) and bioelec-
trical impedance analysis (BIA) , using magnetic resonance
imaging (MRI) as the criterion. Twelve adult male were involv-
ed in this study. Their average age was 36.4±6.4 yrs , height
169.0±5.3 cm and weight 67.1±11.2 kgs. All subjects were
tested using MRI , UWW and 2 kinds of BIA (BIAt and BIAs).
One-way ANOVA with repeated measures was used for data analy-
sis. The results were :
1.Mean values of body fat percentage (BF%) tested by MRI was
18.6±6.7%.
2.The BF% measured by UWW was 15.3±7.2% which was signifi-
cantly less than BF% of MRI by 18%.
3.The BF% measured by BIAt (22.1±5.7%) and BIAs (25.4±6.0%)
were significantly higher than BF% of MRI by 19% and 37% .
It can be concluded that the Siri equation that converts
density to body fat percentage in UWW , and the BIAt and BIAs
predication equation used by the company may be the causes of
the discrepancy with the MRI values. Therefore , the equations
may need to be revised.
Human body fat assessment is of great importance in health