Do obese individuals gain weight than nonobese individuals? Gilbert

B Forbes

ABSTRACT who

A review

were

overfed

under

mass,

body

fatter weight

people than

fat,

fat,

more

percent to

do those

lean,

body more

to

who

are

thin.

tend tissue,

which

on human

to put whereas

bigger

a given

cost

of weight

gain

should

and of

controlled

A likely

explanation

is

assays,

on a large

proportion

of gain

by each investigator, 4) a calculated 12 kcal/g (the theoretical value

Nutr

of

people

tend

Am

tissue.

to

J Clin

be greater

mdi-

in obese

To test this prediction, a review was made ofstudies of overfeeding in adolescent and adult subjects that met the following criteria: 1) 2 wk ofdefined overfeeding with the subjects in a

amount

thin

is a low-energy

the energy viduals.

rang-

cost of induced and oflean body

Therefore,

gain

subjects

for periods

energy weight

fat.

eat

individuals

a high-energy

done conditions

shows that the ofinitial body

and

need

obese

of studies

controlled

ing from 2 to 12 wk weight gain is a function

that

more easily

environment,

3) a range

2) performance

ofinitial

body

of body

fat content

composition

for subjects

studied

energy cost ofweight for fat), and 5) a weight

gain

gain

1 kg.

1990;52:224-7.

Methods KEY WORDS

Weight

gain,

energy

need,

body

fat, obesity, Data of body

thinness

together

Introduction In discussing fronted

with

matters

with

the

ofweight

opinion

remarkable

ease,

uals

will gain data gain

weight

thin

there

at least

overweight

food;

one

the corn-

show that excess energy

interindividual

controlled of

more

answer

can

overweight

to the answer

with

when

be found

over-

in an analwho

together

with

anorexia

nervosa

is to be found

tend

to put

Because

the energy

about

six times

greater

kcal/g

protein)

X (0.205

mass (LBM)] (8, individuals would

individuals

and

rest

were

were

studies

of

under

to gain

on

relatively

cost

than

in the composition

individuals that thin whereas

the

large

of gaining cost

g protein/g

lean)

of

of fat

1 g fat (12 kcal)

of gaining =

1 g lean 1 .78

is

[(8.68

kcal/g

lean

9), one could reasonably predict that have to eat more than would nonobese

a given

amount

of weight.

In other

words,

Am J C/in Nutr

1990;52:224-7.

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type

of diet

that

provided

period.

The

subjects

of Bandini

young

and

et al (12)

middle-aged

the

were

with

extra

adolescents;

adults.

At the

energy

anorexia

ner-

all of the time

of study

the condition of the patients with anorexia nervosa had been stabilized: all had normal values for blood hemoglobin, serum proteins, and electrolytes, and diet was carefully monitored on the metabolic ward. As noted in Table 1 the excess food consisted ofcarbohydrate for 2 1 subjects, offat for 4 subjects, and ofmixed diet for 38 subjects. composition

status

was

estimated

in 24 subjects, by densitometry dilution in 12 subjects. The period

ranged

eral studies. In each reported during overfeeding author was taken ence

when they are individuals gain those with larger amounts

those

Body

conditions.

fat stores

vosa

counting oxygen-l8

vari-

individuals

conditions, patients

readily

the

,

individ-

indeed

experiments to the total

weight

The and

(5-7).

224

and

fed excess

to gain

repletion

A clue

body obese

to have

weight

yet doesn’t gain weight. (1) and Passmore and

thin

tissue gained by thin and overweight overfed. A recent compilation shows relatively large amounts oflean tissue body

gain

.

the overfeeding

feeding tends of normal

under

controlled

seems

is considerable

or the obese?

ysis of studies nutrition

both

when

although

ability (4). Which group

overfed

that

one is apt to be con-

individuals

from several controlled is directly proportional

consumed,

fed-the

obese

to eat to excess and Newburgh

(2, 3) showed

bined weight

control,

that

and everyone

thin friend who claims Many years ago Wiley colleagues

with

during

are listed in Table 1 Included are the ranges LBM, and body fat for each group of subjects

sources weight,

was

from

14 to 83 d (i25

series the difference and the maintenance as the excess energy

subtracted

for

by

fecal

potassium-40

in 27 subjects, and by duration of the overd) among

the

sev-

between energy intake intake as stated by the intake; 5% of the differ-

losses.

However,

a different

method was used for the nine subjects with anorexia nervosa. Once the patients had been stabilized, basal metabolic rate (BMR) was determined and a potassium-40 assay was done.

I From the Departments of Pediatrics and Biophysics, University Rochester School ofMedicine and Dentistry, Rochester, NY. 2 Supported by NIH grants 5 K06 HD 18454 and RR 00044. 3

Address

Box 777,

reprint requests to GB Forbes, Department University of Rochester Medical Center,

of PediatricsRochester, NY

14642.

ReceivedJune 19, 1989. Accepted for publication Printed

in USA.

January

31, 1990.

© 1990 American

Society

of

for Clinical

Nutrition

ENERGY

TABLE Subject

OF

WEIGHT

225

GAIN

1 characteristics,

Number,

diet

sex

weight

Body

Body fat

LBM

kg

kg

kg 13 M

The number

ofsubjects

Type

ofexcess

18

7-33

50-85

Fat [4], carbohydrate

4-54 4-72

49-83 35-76

Mixed diet [8] Carbohydrate(12J

30-93

2-25

28-77

Mixed diet [24]

46- 107

6-43

34-76

Mixed

for each type given

subjects excluded. subject excluded. § One male and eight females with anorexia

Reference

food*

54- 1 15 44-142

59-I

6 M, 2 Ft 8M,4Fj 3 M, 2 1 F 4 M. 2 F II *

COST

[9]

Goldman

et al (10)

Katzeffet al ( 1 1) Bandinietal(l2) Forbes et al (4, 7) Webb and Annis (13)

diet [6]

in brackets.

t Four additional :1:One additional

II Five additional

subjects

nervosa,

all others

normal.

excluded.

vealed

These assays were made twice weekly during nutrition recovery, and excess energy intake was calculated as the difference between actual intake and 1 .5 X BMR; due account was taken ofthe gradual rise in BMR that occurred. Fecal losses were assumed to be 5% ofexcess energy intake. The total excess energy consumed during the overfeeding period ranged from I 6 000 to 80 000 kcal (1 28 500 kcal) for the various studies, and the gain in weight ranged from 1.8 to 14.7 kg. The energy cost of weight gain is determined by dividing the former by the latter and is expressed as kcal/g gain for each subject. Statistical analyses were done on the C/info Data Analysis System (BBN Software Products Corp, Cambridge, MA).

it

Figure

1 is a plot ofexcess

(kcal/g)

against

initial

energy body

consumed

weight

unit

per

rithm

Indeed,

A further sion

the heaviest

as much slope

food

people

as the lightest

analysis

ofthe

for males

does

data

need

to gain

is shown

not differ

over, a comparison of those sisted solely of carbohydrate

on average ones from

that

kcal/g

for

were gain

slopes

are

carbohydrate

done

diet/

on all subjects,

against

initial

LBM,

along

the x-axis

is symmetrical

whereas

those

gain

is greater

for

fatter

people

analysis

than

revealed

for those

the following

who

are

(fat and

LBM in kg): kcal/g

=

5.427

+ 0.0630

fat (±0.017)

+ 0.0126

LBM

(±0.0

18)

(1)

1.7



weight. 2. The regres-

for females.

assays

regress

thin. Multiple-regression

1 g body

in Table

of values

weight

The

to eat

to

regression

except

for weight and fat are skewed. Table 2 shows that energy cost is related to both ofthese body components and to relative fat content, the relationship being somewhat stronger for fat than for LBM. The effect of relative body fatness is shown in Figure 2. The slope of the regression line is significantly different from zero (p = 0.0001). Although there is some scatter of points about the regression line, the trend is evident: the energy cost of

of the regression line is significantly different from zero (p = 0.0002). Despite the rather wide scatter of points about the regression line, the trend is obvious: the energy cost of weight gain is greater for heavy people than for those who are lighter.

zero

body fat, against percent fat, and against the logafat. This last index was chosen because the distri-

ofbody

bution

slope

times

initial

from

composition

body

possible

against

weight

for all 63 subjects.

was

(All of the various

different 0.057.)

=

Because

Results

gain

no difference.

significantly weight, p

The correlation coefficient is 0.490. It is apparent is a more important determinant of the energy gain than is LBM.

More-

subjects whose excess energy conwith those given mixed diets re-

that body fat cost of weight

Discussion Cu

0

0

10

The prediction

#{149}

energy

0

E

who S

Cu (2

0

S

Males

0

Females

40



o0



80



ic;o

Initial Weight, FIG 1. Plot ofenergy weight (kg). Females(O), + 0.039x(±0.OlO), r

=



120



140

cost ofweight gain (kcal/g) against initial males(#{149}).Calculated regression line: v 0.45.



be answered

=

body 4.46

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be greater

ofbody

namely in those

fat than

that

the

individuals

in those

who are

.

.

.

.

.

in the negative. earlier, the reason for the higher energy cost and fatter people is that weight gains induced by overfeeding are composed of a relatively large proportion of fat, whereas thin people tend to gain more lean (5). Two examples from that report, in which the relative contributions of lean As mentioned for overweight

kg

in the introduction, would

have a large component

.

y=4.46+0.039x

,

gain

viduals actually gain weight more easily than do obese individuals. The question posed in the title ofthis paper can therefore

Cl)

Cl) 4) C.)

set forth

ofweight

lean, is confirmed by the data presented. When subjects are studied under controlled conditions, it turns out that thin mdi-

#{149}

S

.

cost

226

FORBES

TABLE

2

Regression

equations

for energy

cost ofweight

gain (kcal/g)

vs weight,

LBM,

Allsubjects(n Weight, kg LBM, kg Fat,kg log fat, kg Percent fat Females(n

fat, log fat, and percent =

fat

63)

4.46 + 0.039 (±0.OlO)* 5.05 + 0.040 (±0.0 18) 6.01 +0.068(±0.016) 4.25 + 2.66 (±0.6 1 7) 5.42 + 0.080 (±0.019)

r = 0.45 r = 0.27 r=0.48 r = 0.48 r = 0.46

< 0.01 p < 0.05 p

Do obese individuals gain weight more easily than nonobese individuals?

A review of studies done on human subjects who were overfed under controlled conditions for periods ranging from 2 to 12 wk shows that the energy cost...
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