Assessment of body fatness in young children using the skinfold technique and BMI vs body water dilution.

OBJECTIVES

To compare body fatness estimated using a skinfold technique and body mass index (BMI) with body fatness estimated using the body water dilution method in healthy Swedish children 9 or 14 months of age.

METHODS

Total body fat (TBF) was calculated from total body water, estimated using the doubly labelled water method, and body weight. When expressed in per cent of body weight, these estimates (%TBF-BWD) represented reference values for body fatness. Body fatness was also calculated from skinfold thickness (%TBF-SFT) and as BMI. The children were ranked and grouped into five groups with an increasing level of body fatness using BMI, %TBF-SFT and %TBF-BWD, respectively.

SUBJECTS

A total of 30 infants 9 months of age and 29 children 14 months of age.

RESULTS

On average, the children (n=59) had a BMI=17.5+/-1.6 kg/m(2) and contained 27.8+/-3.7 %TBF-SFT and 29.1+/-4.4 %TBF-BWD. %TBF-BWD minus %TBF-SFT was=1.35+/-4.06%. By measuring %TBF-SFT or BMI, about 35% of the children could be classified in the correct group with respect to body fatness. Serious misclassification (ie two or more groups too high or too low) was, however, more common for %TBF-SFT (29%) than for BMI (17%).

CONCLUSIONS

The capacity of BMI to place children in the correct body fatness group was poor although not quite as poor as the corresponding capacity of the skinfold technique. The latter method produced inaccurate and imprecise estimates of body fatness.