The five-level model: a new approach body-composition research1’2 Zi-ifian

Wang,

Richard

ABSTRACT man

Jr. and

Body-composition

biology

position

N Pierson

that

levels

has and

three

research

areas:

organizational

B Heyms/leld

is a branch

interconnecting

their

Steven

rules,

of hu-

body-com-

Although

ofincreasing III, cellular;

each

level

biochemical and model is consistent provides

steady

a specified

or different for

creating

new

KEY

state Finally,

explicit

are distinct,

quantitative

the five-level

model

J C/in

Body

provides

and Nutr

composition,

body

a matrix reveals

suggests

describe subjects

0.732]

=

gaps

assessment.

state

not

only

levels

between

The

Another

of human

search. within

Nearly many

science

are touched

every medical

Information rapidly

emerging been

is now

with the

niques

involved.

to

The

biological growth, disease

no

methodology

are often

published.

category

includes

biological

most

body-composition

categories information,

has such

as

which are ofthe tech-

.1,71

i C/ui Nuir

information be satisfactorily 1992:56:

19-28.

in USA.

body

or different

are

mass,

and

The

and

we could

mass of clear

a subtle

no clear

approach

multicompartment

in extensive

reviews

observations

but

in published bodyofoverlap or omis-

find

building

Are

body lack

has

In fact,

con-

example: lean

components

sion

these

different

frequently For

compartments?

for body-composition

components

by neuexist

between

terminology.

fat-free

models

quan-

to body-

of previous

literature.

is the hypothesis

that

a third

central category of body-composition research exists that until now has not been adequately formulated: the levels of body composition

and

their

a comprehensive of five distinct level has clearly five levels

system:

and

rules.

ofhuman

body

levels of increasing defined components are I. atomic:

V. whole

following and

organizational

model

section

its associated

tures or organizational scribed. Important

(Fig

presents

composition

models

ofthe

paper,

and

the widely

and

fined

concept

ofa

steady

III, cellular:

a detailed

each Bwt.

IV. tissue-

next

of each

section

the

fea-

model as a whole are deto development of bodyare presented

appreciated ofbody

description

In the

of the related

equations state

presents consisting

I).

components. rules concepts

report

complexity in which that comprise total

II, molecular:

body

This

composition

but

in this never

composition

portion

formally

de-

is introduced.

lactation, I

would

appear a recent

emerging from body-composition included into the technical Printed

but

investigators

about

mass,

from

body

some

information

study ( 1 ) led us to appreciate a serious limitation of the field as it is now organized. We recognized that not all of the rapidly accumulating research could

components

is that

ofcomponents.

that

the relationships among Another example is prochemical compartments

many errors are evident and models because

The sys-

indicates

serious consequence: composition equations

level

continually

development, pregnancy. influence body composition. and

Most

or biological. and

Although

body-composition

the technical

encompass

classic

and neutron-activation analysis. principle or other characteristics

on the study ofhow aging. exercise, and Although

biology.

components

(TBW)/fat-free

as well.

questions same

mathematical

different

water

formulation

individual

body

(LBM)

The

is accumulating

methods.

groupings

re-

composition.

as technical

the many

y and

clinical

selected areas of exercise

ofhuman

categorized

for

informal

nutrition, components of body

100

>

and

composition

body-composition

dilution techniques based on a physical

science

knowledge

includes

classification proposed.

study

body

our

category new

tematic

to

is extending

technical

spans

of basic

on by the

information

The

composition

area

aspect of clinical specialties, and

related

and

ofthis

body

to be an active

body

are many

from elements estimated in vivo ( 1 ). This suggests that relationships

problem

fronted

Growing

study

total

composition

composition

continues

[eg,

(2). This

of body

defining

Introduction

there between

and body weight (Bwt) tron-activation analysis

definitions

1992:56:19-28.

For example, the relations

titative associations exist that describe compartments that are in equilibrium. vided by the reconstruction of human

lipid-free

important

nutritional

mass

exist

at the same

equations,

composition,

.1,n

ofa

associations

compartments

body

areas.

the concept

between

body-composition

WORDS

steady

define

in which

interval

ofhuman

research

compartments

to clearly

time

levels.

in the study

compoat pres-

physiological connections exist such that the and functions as a whole. The model also

the opportunity

composition over

its multiple

categories. that

in healthy

complexity are proposed: I, atomic: IV, tissue-system: and V. whole body.

and

biological models

measurement

techniques, and biological factors that influence body sition. In the first area, which is inadequately formulated ent, five levels II. molecular:

to organizing

© 1992 American

and Society

Downloaded from https://academic.oup.com/ajcn/article-abstract/56/1/19/4715618 by Denise Hannibal user on 19 May 2018

From

the Obesity

Research

Center.

St Luke’s-Roosevelt

Columbia University. College of Physicians and Surgeons. NY. 2 Address reprint requests to Z-M Wang, Weight Control West I 14th Street, New York, NY 10025. Received September 17, 1991. Accepted for publication December 12. 1991. for Clinical

Nutrition

Hospital, New Unit.

York, 4I1

19

20

WANG

ET

AL

TABLE 1 Body composition Man

on the atomic

level (I) for the 70-kg

Amount

Percent

Element

Reference

ofbody

kg

Le1I (Atoalc)

FIG 1. The five levels of human body extracellular fluid and solids, respectively.

composition.

ECF and

43 16 7 1.8 1.0 0.58 0. 14 0. 14 0.1 0.095 0.019

61

Total

69.874

99.537

Information

related

fundamental

or elements.

building

Ofthe

blocks

gen, Bwt,

nitrogen, and one

mass

in the

elements

calcium, element, up

equation

body

are found

are atoms

Man

account > 60%

1) (2).

(Table

The

organs hydro-

ponents

for > 98% of of total body remaining

44

as defined

in the

atomic

level

of body

percent

mass

of Bwt

Elemental

(1)

analysis

ofall

elements

present

in amounts

of humans

is traditionally from content

carried

out

be measured directly in vivo: potassium by whole-body sodium, chlorine, and calcium by delayed--y neutron-

activation analysis

analysis (3); nitrogen by prompt-’y neutron-activation (1 , 3): and carbon by inelastic neutron scattering 98%

can

be

techniques. position

of Bwt

estimated The

analysis

P110/cell/ar

(II)

The

1 1 principal

from

water

possible in living search

>

is water,

major

lipid

components

(L);

protein

in present

(Pro):

use

mineral

(M):

2). Because some confusion exists in we now review the five chemical corn-

abundant

which

chemical

comprises

compound

60%

of Bwt

in the human in the

Reference

(2).

The

includes

atomic and

can

now

in

vivo,

level is the

be reconstructed largely is the

starting

elements

100 000 molecules

by

from

term

almost

protein

in body-composition

all compounds

humans. is to consider

all ofthese The

alternative

chemical

density

are

point

research

containing

usu-

nitrogen,

ranging

distribution

1% and

at 37 #{176}C (1, 5).

g/cm3

The primary storage form is found in the cytoplasm is in skeletal

2.2%

of their

muscle

respective

TABLE 2 Body composition Man*

acid. chemical used

on the molecular

of carbohydrate of most cells. and

wet

liver,

weights

The

is glyprim-

which

contain

in the

form

of

five

into

levels

Component

Amount 1cv

we

molecules

found in the and molecular It is neither compounds

human weight

Reference

useful

nor

Water Extracellular Intracellular Lipid Nonessential Essential Protein Mineral

(fat)

Total

Percent

of body

weight

%

18 24

26 34

12 1.5 10.6 3.7

17 2.1 15 5.3

69.8

99.4

individually

in body-composition in categories

level (II) for the 70-kg

(4).

elements

of body-corn-

for the

incorporated

compounds

of 1.34

G/i’cogen. cogen. which

neutron-activation

foundation

chemical compounds range in complexity

to deoxyribonucleic

to measure

and

in

propose.

that form body. These

(G) (Table categories.

in detail. The most

Protein. ally

The

(A):

selected tissues and organs. of most major elements

can now counting:

than

body Man

cipal

(1).

cadavers or in biopsy specimens In addition, the whole-body

that

2 (modified).

from simple amino acids to complex nucleoproteins. The most widely used representative stoichiometry for protein is CH 59N26O32S07 . with an average molecular weight of 2257.4

is

R is the residual

0.2%

Water.

2% of Bwt.




100 y, and

However, what

five-level

is conducive

exactly model

appropriate

or rules.

terconnecting ponents and

cellular,

tissue-system,

ing the

methods

studying

the

influences

components

(Fig

and

research the proportions associations

of measuring

and various

by in

for define

bodyhuman

that studies steady-state

includes

three

in-

of various cornamong the atomic,

whole-body factors

what

presented

levels:

components

of biological

term

is meant

structure to clearly

Body-composition

areas: studying their steady-state

the

it is unclear

body composition as a branch of human biology various body compartments and their quantitative

study-

in vivo; on

various

and levels

5).

Conclusion

as Bwt

=

molecular

direct

The

five-level

is body

X BV

volume

on the whole-body

that

in

model

developing relate

is intended or expand

method

2.057

=

of body

composition

composition

serves

in

broader

grows

methodologies

to the study

ofhuman

to be a foundation selected definitions this organizational view

of body-composition

from

a need and body

to organize

both

physiological composition.

the

concepts The

model

on which future studies can refine or equations. The five-level model capacity and also stimulates a research

as a whole.

C]

level, 12.1

References

indirect also

anthropometric

are

fat=4.95XBV-4.5OXBwt,andfat=0.7l5XBwtx stature2 (in m) (19, 20). Thus

research.

of in-

evaluating

presently

measurements

1 : 2) from

also

topic

molecular.

compart-

important

indirect ofdirectly

All ofthe

mea-

steady-state relationunknown components.

number

methods

the

shows and

are

rapidly

TBK(mmol)/68.

level

methods

relations

unknown

combining

fat is a major

on direct

skinfold

many

At present,

body

such

levels.

only

no practical

based

the table

Definition

imaging

indices and

a few direct

expand

be evaluated.

and

1) from

on

effects

6. The table demonstrates and

respectively

body-composition

follows:

-

I Biological

by com-

on the atomic

composition

be assessed

fat compartment indirect

I

ofbody-composition

that

from levels.

versely,

vol-

and

developed

whole-body on the cellular

resonance

composition.

methods.

can

are

mineral

(18).

tissue-system

can

there

been

determined

anthropometric

body

greatly

although

terest.

V

of subcutaneous

by magnetic

there

are only

methods

measured

by

(and plasma isotope-dilution

volumes

surernent techniques with the established ship between the directly measurable and Indirect

directly

estimated

osseous

fluid several

are concentrated

of body

and

(24).

circumferences,

neasuremnent

components

and

be directly

directly

and

presented principal

(4).

be directly

the

level,

ofhurnan

direct

lecular,

can

stature,

ofthe

scattering (10),

and

be estimated

can

used

areas

in Table elements

amples of the

portant

tomography

volume,

(23):

absorptiometry

level,

tissue

axial

nesses

and

rules

j

FIG 5. The three

(3):

activation

activation

can

level, extracellular determined by

puterized

body

TBW

techniques

(25). the tissue-system

visceral

neutron

by dual-photon

the cellular can be directly

Bwt,

IV,

com-

to the five-

neutron

neutron

level,

3) On

and

according

I, II, III,

_

L Methodology

tech-

of body

Composition

composition

I

methods,

radioisotopic

be organized

by prompt--)’

be quantified

ume)

and components

on Levels Body

to the five-level in a more sysdirect

of Body

Components

TBK can be directly determined by ( 12): total body sodium. chlorine.

calcium

total

can

catemeth-

are some

biochemical, to estimate

primarily as dilution

According be organized

There

be used

atomic level, #{176}Kcounting

phosphorus,

several

such

Study

as follows:

1) On whole-body

2)

are

groupings

27

MODEL

The

ods and neutron-activation analysis. model, however, the methods can

level

COMPOSITION

to 1flC’t/lOdOl()tl’

gorized

such

BODY

methods

are

not

only

are dependent

on the

and

components

unknown

based

on

steady-state as de-

populations.

and indirect body-composition according to the five-level model

methodology as shown

can be by the ex-

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