Comparison Of Commonly Used Equations For The Estimation Of Body Fat In 18-21 Year Old Males

Introduction
Body composition is an important parameter of health-related fitness. The most commonly used method for the
estimation of body fat in everyday practice involves measurements of skinfold thickness and the use of populationspecific
equations, from which the percent body fat is determined. However, different equations may give different
percentages of body fat, which may, in turn, erroneously alter the recommendations for weight loss. Thus the purpose of
the present study was to compare the percent body fat, fat free mass and recommended fat loss derived from six
commonly used skinfold equations in physically active young males.

Methods
The participants were 747 physically active male students of the Greek Air Force Academy (age: 19.1±0.0 y, Ht:
176.5±0.2 cm, Wt: 74.8±0.3 Kg, mean±SEM). Six different age and sex specific equations were used for the calculation
of percent body fat, fat mass (FM), fat free mass (FFM) and desirable fat loss, assuming a reference body fat value of
13% for this group of subjects [1]. The following skinfolds (skf) were used in each equation: 7-skf equation [4]: chest,
midaxillary, triceps, subscapular, abdomen, suprailiac, thigh; 4-skf equation [4]: abdomen, suprailiac, triceps, thigh; 4-
skf equation [2]: biceps, triceps, subscapular, suprailiac; 4-skf equation [3]: biceps, triceps, subscapular, suprailiac; 3-
skf equation [4]: abdomen, chest, thigh; 3-skf equation [4]: abdomen, suprailiac, triceps. Means were compared using a
one-way analysis of variance and Tukey post-hoc test.

Results
The four equations by Jackson & Pollock [4]gave similar percentages of body fat (from 10.4±0.1% for the 7-skf to
11.2±0.1% for the 4-skf). However, the two equations by Durnin & Rahaman [2] and Durnin & Womersley [3] gave
much higher percentages of body fat (15.6±0.1% and 15.0±0.1%, respectively; P<0.001). The 7-skf equation by
Jackson & Pollock (7-JP) and the equation by Durnin & Womersley (4-DW) were subsequently compared (see Graph
1). The average FM was lower (7.9±0.1 vs 11.4±0.1; P<0.001) and FFM was higher (66.9±0.21 vs 63.4±0.2; P<0.001)
when calculated from the 7-JP compared with the values derived from the 4-DW. The number of subjects that had a
percent fat higher than the reference value of 13% was 547 (73.2% of total) when calculated from the 4-DW and only
149 (19.9% of total) when calculated from the 7-JP.

Discussion/Conclusions
The results of this study show that the percentage of body fat, FM, FFM and recommended fat loss may be heavily
influenced by the selection of the skinfold equation. The reference values for the desirable body composition may need
to be adjusted when recommendations for fat loss are based on calculations from different skinfold equations.

References
[1]. ACSM. (1998). ACSM’S Resource Manual, Baltimore, Williams & Wilkins
[2]. Durnin J.V. and Rahaman M.M. (1967) Br J Nutr. 21: 681-689
[3]. Durnin J.V. and Womersley J. (1974) Br J Nutr. 32: 77-97
[4]. Jackson A.S. and Pollock M.L.(1978) Br J Nutr. 40: 497-504

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