| Objective:
Body mass index (BMI) is now widely accepted as a means of classifying
under, normal, and overweight (UW, NW & OW) (i.e., <18.5,
18.5 to <25, and >+25 kg/m²). As BMI is used as a
proxy for body composition, we recently developed corresponding
% fat ranges (Table 1) on 1129 subjects using a 4-compartment
method as the reference for body fat. Subjects below, within,
or above the age-sex % fat ranges are under, normal, and over-fat
(UF, NF, & OF), respectively. The aim of the present study
was to examine in a healthy subject cohort the frequency of misclassified
subjects based upon BMI. Subjects were excluded with extremes
of physical activity and % fat was measured using DEXA.
| BMI |
SUBJECTS |
MISCLASSIFICATIONS |
| N |
N |
UW |
NW |
NW |
OWA |
| (F) |
(M) |
NF |
UF |
OF |
NF |
| <18.5 |
11 |
2 |
3/0 |
|
|
|
| >=18.5<=25 |
96 |
78 |
|
17/14 |
10/14 |
|
| >=25 |
95 |
83 |
|
|
|
12/27 |
|
|
|
(female/male) |
Table 2: Subjects misclassified by BMI
|
Results:
The subject pool consisted of 202 females and 163 Males (Table
2). Subjects were organized into one of a 4 misclassification
groups: UW-NF, NAW-UF, NW-OF, OW-NF, 42/202 females (20.8%) and
55/163 males (33.7%) were misclassified on fatness according
to BMI. These observations suggest misclassification of
fatness by BMI may occur in over one-fourth of healthy adults. Future
studies are needed to establish the clinical significance of
these observations.
| FEMALES |
AGE |
| BMI |
20-39 |
40-59 |
50-79 |
| 18.5 |
19% |
19% |
20% |
| 25 |
34% |
35% |
36% |
| MALES |
AGE |
| BMI |
20-39 |
40-59 |
60-79 |
| 18.5 |
6% |
8% |
10% |
| 25 |
20% |
22% |
24% |
Table 1: Corresponding % fat ranges for BMI
|
