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

Por: A. Tsetsonis e G. C. Bogdanis.**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

**NOTA:** O texto com a iconografia está no anexo