Chapter 3
Preventing weight gain and promoting physical activi
Preventing weight gain and changing thephysical activity habits of individuals andpopulations present a formidable set ofchallenges. Patterns of food intake andphysical activity in individuals and popu-lations are subject to a plethora of influ-ences at severallevels (see Chapter 1).What people eat and how active or inac-tive they are can be influenced by
genetic and biological factors; by psy-chological states, traits and learned habitpatterns; by family, community and otherproximal social influences; by organiza-tional structures at work and other formaiand informai social systems; by barriersand opportunities in people's physical
environments; by economic factors thatinfluence access ta private and publicresources; and by the broad political,economic and social processes that ulti-mately shape the patterns of behaviouralchoice in who le populations. It is there-fore not surprising that even the bestplanned and most carefully implementedefforts to prevent weight gain and pro-mate physical activity have shawn onlymodest results.
As the body of scientific evidence inthis Handbook makes c1ear, preventingweight gain and promoting physical
activity should be central to the cancer-preventive agendas of ail countries.Thus, we have a strong imperative forpreventive action, but still only limitedknowledge of the likely effectiveness ofdifferent types of intervention. Most inter-ventions for weight gain prevention or forpromotion of physical activity haveshown only modest changes that usuallywere not weil maintained over time afterthe intensive intervention phase. Theway forward for cancer-prevention
initiatives based on weight gain preven-
lion and physical activity promotion mustbe guided by both realism and by thebest use of the available scientificinformation.
Diet and prevention of weightgainThis Handbook has a primary focus onprevention of weight gain and promotionof physical activity. However, energy bal-ance can also be maintained by limitingenergy intake. Optimal ways to preventweight gain by dietary modification arelargely unknown. Epidemiological stud-ies tend to suffer from increasing under-reporting of food intake with increasing
body weight (Seidell, 1998). Interventionstudies usually have tao limited durationand too few participants to allow properevaluation of the long-term effects on
body weight in populations. There arealso many dimensions of food intakeother than just energy intake that mayplay a role (Table 14). These include
macronutrient composition, energy den-sity, food palatability and pleasure of eat-ing, portion sizes and meal patterns
(e.g., nibbling versus gorging) (Table 15).
Physical, economic and socioculturalfactors also influence dietary intakes atthe levels of populations, households andindividuals (Egger & Swinburn, 1997).
Influences of diet on weight gain
al ways interact with that of physicalactivity. For example, regular physicalactivity influences fat and substratebalance. This effect is considerable
wh en an activity is maintained over along period; physically trained individualsmetabolize more fat at equivalent levelsof energy expenditure than untrained
individuals (Hurley et al., 1986). Stubbset al. (1995) showed that volunteers whowere moderately active were able ta
Macronutrient Energy content
kJ/g kcal/g
CarbahydrateFatPrateinAlcahal
16371729
4947
Protein Carbohydrate Fat
Ability ta end eating High Moderate LawAbility ta suppress hunger High High Law
Starage capacity Law Law HighPathway to transfer excess Yes Yes Nata alternative campartment
Ability ta stimulate awn Excellent Excellent Paaraxidatian
41
IARC Handbooks of Cancer Prevention, Volume 6: Weight Control and Physical Activity
consume ad libitum diets with 40%energy from fat, whereas the same indi-viduals when sedentary gained weighton the same diet. It is therefore thoughtthat people who sustain moderate or
high levels of physical activity are lesslikely ta gain weight when they eat dietswith a high fat content (35-40% of
energy). Because fat is a major contribu-tor to overall energy intake, lower fat
intake (e.g., 20-25% of energy) may beneeded to minimize energy imbalance
and weight gain in sedentary individuals.Physical activity not only influences foodmetabolism. It also interacts with foodchoice and may also affect energy bal-ance through its effects on food intakeand preferences. Information on this israther limited.
Prevention of weight gainthrough physical activityBecause both weight gain and weightloss are functions of energy balance,
prevention of weight gain could theoreti-cali y be achieved by changes in eitherdietary energy intake or physical activity
(energy expenditure). Weight reduction
resulting from increased physical activitywithout restricted energy intake is onlymodest (Garrow & Summerbell, 1995;National Institutes of Health and NationalHeart, Lung, and Blood Institute, 1998(Figure 22). ln contrast, many recentreviews have underscored the impor-
tance of physical activity in prevention ofweight gain (Saris, 1998; Ravussin &Gautier, 1999; Wing, 1999; Jeffery et al.,2000). However, because of the narra-tive and non-systematic nature of mostavailable reviews, a systematic review
was undertaken to evaluate ail researchreports with data on physical activity andweight gain, published between 1980and early 2000 (Fogelholm & Kukkonen-Harjula, 2000). The following section isbased on that review. It is important tanote that the review was restricted taCaucasian (white) adults, because com-prehensive data were available only forthis group.
42
The following criteria were applied inselecting prospective, observational
studies for inclusion in the review:
. data on physical activity and change
of weight (or BMI) were provided;. duration of follow-up was at least two
years;. no intervention was performed;
. studies on weight change during
special circumstances, e.g., aftersmoking cessation or during preg-nancy, were excluded.
Seventeen prospective observationalstudies (Rissanen et al., 1991; Klesgeset al., 1992; Owens et al., 1992;
Williamson et al., 1993; Taylor et al.,1994; Bild et al., 1996; Haapanen et al.,1997a; Heitmann et al., 1997; Kahn etal., 1997; Parker et al., 1997; Barefoot etal., 1998; Coakley et al., 1998; Thune etal., 1998; French et al., 1999a; Guo etal., 1999; Crawford et al., 1999;
Fogelholm et al., 2000a) fulfilled thesecriteria (Table 16). The mean duration offollow-up was approximately seven
years, with a range from 2 to 21 years.Ali studies used a retrospective ques-
tionnaire to assess the habituai (usuallyover the past year) level of physical
activity. Three studies (Rissanen et al.,1991; Parker et al., 1997; Thune et al.,1998) used a rough, subjective classifi-cation into 2-4 activity classes. Most
studies assessed physical activity ofboth moderate intensity and more
intense activities. Two studies focusedon vigorous exercise activities (Barefootet al., 1998; Coakley et al., 1998). Threestudies also assessed occupational (ornon-recreational) activity (Klesges et al.,1992; Williamson et al., 1993; Guo et al.,1999). Finally, Coakley et al. (1998) andCrawford et al. (1999) asked specificallyabout television and video use.
The outcomes of the studies may begroupec( according ta wh en physicalactivity data were collected, that is,whether baseline, follow-up or change(from baseline to follow-up) in physical
activity was compared against change inweight. The studies using baseline phys-ical activity data yielded inconsistent
results. ln three (Klesges et al., 1992;
Owens et al., 1992; Haapanen et al.,1997a), an inverse relationship betweenbaseline physical activity and weightchange was seen, Le., a large amount ofphysical activity was associated withsmaller weight change. However,Haapanen et al. (1997a) reported thisinverse relationship for men, but not forwomen. High baseline activity at workwas associated with less weight gain inthe study by Klesges et al. (1992). lncontrast, two studies reported that alarge amount of vigorous physical activityat baseline was associated with greaterweight gain (Klesges et al., 1992; Bild etal., 1996). Finally, three studies did notfind a significant association between
baseline total physical activity(Williamson et al., 1993; Parker et al.,1997) or television and video watching(Crawford et al., 1999) and the magni-tude of weight change.
Figure 22 Difference in weight: The bodyweight of a person doing physical activity alsoaffects the amount of energy used. A personweighing 220 kg will expend more energywalking for 30 minutes than a gO-kg persan
(Sumo wrestler Akebono and his son Hiroshi)
Ref
eren
ceSu
bjec
ts, s
exFo
llow
-up
Ass
essm
enl o
f ph
ysic
alSt
alis
tical
Main effecls Results
~ge
at e
ntry
)ac
tivily
adju
stm
ents
of P
A
Ris
sane
n et
al.,
199
1 61
65 M
, 650
4 W
5.7
yLe
isur
e P
A a
t fol
low
-up
Age
, BM
I, ed
ucat
ion,
+P
A a
t fol
low
-up
was
inve
rsel
y as
soci
ated
(25-
64 y
)(m
edia
n)(q
uest
ionn
aire
, 3 c
ateg
orie
s:marital status, parity,
with
wt g
ain
in m
en a
nd w
omen
freq
uent
, occ
asio
nal,
rare
)sm
okin
g, a
lcoh
ol,
coffe
e, h
ealth
sta
tus
Kle
sges
et a
l., 1
992
142
M, 1
52 W
2 y
Leis
ure
spor
ts a
ctiv
ity a
ndB
asel
ine
wt,
diet
,+
/ns/
-B
asel
ine
wor
k (ß
= -
3.5)
and
leis
ure
(mea
n 34
y)
occupational PA score
preg
nanc
y, s
mok
ing,
(ß =
-6.
2) a
ctiv
ity p
redi
cted
wt l
oss
ln(B
aeck
e P
A s
cale
) (d
ata
alco
hol,
fam
ily r
isk
ofW
, but
not
in M
. Bas
elin
e sp
orts
act
ivity
collected annually)
obes
itypr
edic
ted
wt g
ain
in W
(ß
= 3
.0)
and
M
(ß = 1.9).
Ow
ens
et a
l., 1
992
500
W (
42-5
0 y)
3 Y
Lels
ure
habi
tuai
PA
Sex-
horm
one
use,
+Both base
line
PA
and
incr
ease
d P
A(P
affe
nbar
ger
ques
tionn
aire
;sm
okin
g, c
hang
e in
wer
e as
soci
ated
with
less
wt g
ain
kcal
/wk)
men
opau
sal s
tatu
s
Will
iam
son
et a
l.,35
15 M
, 581
0 W
10 y
Non
-rec
reat
iona
l and
Age
, BM
I, ra
ce, e
duca
tion,
+W
t cha
nge
was
inve
rsel
y as
soci
ated
1993
(mea
n 47
y)
recr
eatio
nal P
A (
thre
e-po
int
smok
ing
stat
us, a
lcoh
ol,
with
PA
at f
ollo
w-u
p. D
ecre
ased
PA
scal
e)ph
ysic
ian-
diag
nose
dw
as a
ssoc
iate
d w
ith w
t gai
n. B
asel
ine
health conditions, pa
rit y
P
A w
as n
ot a
ssoc
iate
d w
ith w
t cha
nge.
Tay
lor
et a
l., 1
994
568
M, 6
68 W
7 y
Moderate and heavy PA.
Age
, sm
okin
g, s
ex+
Incr
ease
d P
A (
com
pare
d to
sta
ble
or(2
0-60
y)
TV
wat
chin
g (h
/day
)de
crea
sed
PA
) w
as a
ssoc
iate
d w
ith le
ssw
t gai
n
Bild
et a
l., 1
996
1100
M, 1
096
W2 y
PA
sco
re (
inte
nsity
and
Age
, BM
I, pe
rcep
tion
ofns
/-L
ow b
asel
ine
PA p
redi
cted
wt l
oss
(18-
36 y
)du
ratio
n of
PA
at l
eisu
refa
tnes
s, p
hysi
cal f
itnes
s,(O
R =
0.0
5) in
M. C
hang
e in
PA
and work)
educ
atio
n, s
mok
ing,
die
t,w
as n
ot a
ssoc
iate
d w
ith w
t cha
nge.
-0 eial
coho
l"" C
D ~H
aapa
nen
et a
l.,25
64 M
, 269
5 W
10 y
Leis
ure
PA
(sc
ores
, gro
uped
Age
, per
ceiv
ed h
ealth
+/n
sN
o re
gula
r P
A a
t bas
elin
e w
as a
ssoc
iate
dS' eo
1997
a(1
9-63
y)
into
tert
iles)
and
sin
gle-
item
stat
us, s
mok
ing
stat
usw
ith ?
5 k
g w
t gai
n in
W (
OR
= 1
.6),
but
:: CD
self-
asse
ssm
ent o
f tot
al P
Aand socioeconomic
not i
n M
(vi
goro
us a
ctiv
ity tw
ice
a w
k w
ascë
ï ;:(4
cla
sses
)st
atus
used
as
refe
renc
e). I
nact
ivity
at f
ollo
w-u
peo
was
inve
rsel
y as
soci
ated
with
wt g
ain
in'" S'
both
gen
ders
(O
R =
2.6
-2.7
). B
ecom
ing
'" ::ph
ysic
ally
inac
tive
was
als
o as
ssoc
iate
d0. -0
with
wt g
ain
(OR
= 2
.0-2
.5).
a :3
PA
at f
ollo
w-u
p w
as n
ot a
ssoc
iate
d w
ith~
Hei
tman
n et
al.,
2110
M, 2
490
W6 y.
PA
dur
ing
leis
ure
(cla
ssifi
edA
ge, s
mok
ing,
zyg
osity
,ns
s' eo19
97(t
win
pai
rs)
into
3 c
lass
es b
y te
rtile
s of
BM
I at e
ntry
, cha
nge
inw
t cha
nge
(mul
tiple
reg
ress
ion)
-0 =(1
8-39
y)
tota
l ME
T v
alue
s) a
t fol
low
-up
BM
I of t
he tw
in p
air
'" Ul
e'ï eL '"
ti 1
i~ ~
t 1
IRJI
iII!
lil'O
l' i.
~ -
ìil~
imi¡m
ïl ~
ruJl
!rr
Jl1i
1l~
~~
im1
¡~IM:~!ll"'llml~inrOOm! ..I.'~ir~
1 ;¡ ;; ("
Ref
eren
ceSubjects, sex,
Follo
w-u
p A
sses
smen
t of
phys
ical
Stat
istic
alMain effects Results
:i tu ::(a
ge a
t ent
ry)
activ
ityad
just
men
tsof
PA
c: 0- a aK
ahn
et a
l., 1
997
35156 M,
10 Y
Jogg
ing,
aer
obic
s, te
nnis
,Age, education, region
Com
pare
d w
ith n
o ac
tivity
, jog
ging
;: 1
'"+
enW
gard
enin
g an
d w
alki
ng (
h/w
k). o
f the
cou
ntry
, BM
I at a
geh/
wk
(M,W
), a
erob
ics
;: 1
h/w
k (M
) or
;:s.
44080 (mean
Bot
h ba
selìn
e an
d fo
llow
-up
18 y
, mar
ital s
tatu
s, d
iet,
4 h/
wk
(W),
tenn
is 1
-3 h
/wk
(W)
gard
enin
g(" tu ::
40 y
)da
ta w
ere
quer
ied
at fo
llow
-al
coho
l, sm
okin
g, m
eno-
;: 1
/wk
(W)
or ;:
4 h/
wk
(M)
and
wal
king
;:(" ~
up.
paus
ai s
tatu
s, e
stro
gen
;: 4
h/w
k w
ere
asso
ciat
ed w
ith s
igni
fican
t-i
use,
par
ityB
Mllo
ss (
mea
n -0
.08
to -
0.49
kg/
m2)
.eD -c (1
Par
ker
et a
l., 1
997
176
M, 2
89 W
4 y
Par
ticip
atio
n in
aer
obic
No
asso
ciat
ion
betw
een
base
lìne
aero
bic
;:ns
e,(m
ean
47 y
)ac
tivity
(di
chot
omou
s) a
tex
erci
se a
nd s
ubse
quen
t wei
ght c
hang
e.::
base
lìne.
(ter
iles)
2i e: 3B
aref
oot e
t al.,
199
838
85 M
, 841
W21 Y
h/w
k (q
uest
ionn
aire
) at
BM
I at e
ntry
, sm
okin
g,+
Exe
rcis
e w
as n
egat
ivel
y co
rrel
ated
with
wt
(1
(mea
n 19
y)
follo
w-u
pge
nder
, dep
ress
ion
gain (ß = -0.88).
0 :2C
oakl
ey e
t al.,
199
810
272
M4 Y
Vig
orou
s P
A (
min
/wk)
,A
ge, d
iet,
smok
ing,
Vig
orou
s P
A (
ß =
-0.
16)
and
TV
NC
R u
se(1
+,;:
ï(4
4-54
y)
TV
NC
R w
atch
ing
(h/w
k)ba
selìn
e va
lues
(in
clud
ing
(ß =
0.0
2) a
t fol
low
-up
(adj
uste
d to
bas
e-;: ("
(que
stio
nnai
re)
PA a
nd T
VN
CR
use
)lin
e va
lues
) w
ere
asso
ciat
ed w
ith w
t cha
nge.
a ;:T
hune
et a
l., 1
998
5220
M, 5
869
W 7
yLe
isur
e P
A a
t bas
elin
e an
dA
ge, s
mok
ing,
cof
fee,
+S
usta
ined
hig
h or
incr
ease
d P
A w
asSi tu
(20-
49 y
)follow-up (questionnaire,
diet
ary
fat,
men
opau
sal
asso
ciat
ed w
ith le
ss w
eigh
t gai
n du
ring
:: c:P
A g
rade
d in
four
gro
ups)
stat
usthe follow-up period.
-i :: "'Fr
ench
et a
l., 1
999a
228
M, 8
92 W
4 y
Leisure PA score (annual
Age
, die
t, ba
selin
eT
he c
umul
ativ
e du
ratio
n of
incr
ease
d P
Aen
ns¡=
.(m
ean
35 y
)qu
estio
nnai
re)
valu
esw
as n
ot s
igni
fican
tly a
ssoc
iate
d~ ;¡
(ß =
-0.
035)
with
wt l
oss.
Q.
:e.
Guo
et a
l., 1
999
102
M, 1
08 W
9.1
yLe
isur
e an
d oc
cupa
tiona
lA
ge, m
enop
ausa
l sta
tus,
+/n
sC
ompa
red
with
hig
h P
A (
thro
ugho
ut th
e~
(mea
n 44
y)
(mea
n)P
A s
core
; ind
ivid
uals
div
ided
dura
tion
of e
stro
gen
use
entir
e st
udy
perio
d), l
ow a
nd m
ediu
m P
Ain
to th
ree
PA g
roup
sw
ere
asso
ciat
ed w
ith w
t inc
reas
e (2
.8 a
nd(b
iann
ual q
uest
ionn
aire
s)1.8 kg, respectively) in M, but not in W.
Cra
wfo
rd e
t al.,
199
9 17
6 M
, 705
W3 Y
TV
wat
chin
g (h
/day
)B
asel
ine
BM
I, ob
esity
nsT
V v
iew
ing
at b
asel
ine,
ave
rage
TV
(20-
45 y
)prevention treatment, age,
view
ing
and
chan
ge in
TV
vie
win
g w
ere
educ
atio
n, b
asel
ine
smok
ing,
not a
ssoc
iate
d w
ith w
t cha
nge.
diet
(m
ultip
le r
egre
ssio
n)
Foge
lhol
m e
t al.,
442
M (
36-4
9 y)
10 Y
Leis
ure
PA
sco
re (
inte
nsity
Age
, wei
ght a
t age
20,
+/n
sIn
crea
sed
PA
was
neg
ativ
ely
asso
ciat
ed20
00a
x du
ratio
n x
freq
uenc
y)w
eigh
t at e
ntry
, chr
onic
(ß =
- 2
.23)
with
wt c
hang
e. N
o as
soci
atio
ndi
seas
es, s
mok
ing,
occ
upa-
for
decr
ease
d P
A, c
ontin
uous
hig
h P
A o
rtio
nal c
lass
, die
t, al
coho
l,continuous low PA YS. wt change.
mar
ital s
tatu
s, fo
rmer
~rts training _
----
----
---_
._--
~---
-A
bbre
viat
ions
: ß, b
eta
coef
fici
ent i
n m
ultip
le r
egre
ssio
n; B
MI,
bod
y m
ass
inde
x; h
, hou
rIs)
; M, m
en; M
ET
, met
abol
ic e
quiv
alen
ts; n
s, =
no
asso
ciat
ion
betw
een
phys
ical
act
ivity
and
wei
ght m
aint
enan
ce; O
R, o
dds
ratio
; PA
, phy
sica
l act
ivity
; W, w
omen
; wk,
wee
k(s)
; wt,
wei
ght;
y, y
ear(
s); +
, phy
sica
l act
ivity
ass
ocia
ted
with
bet
ler
wei
ght m
aint
enan
ce;
-, p
hysi
cal a
ctiv
ity a
ssoc
iate
d w
ith p
oore
r w
eigh
t mai
nten
ance
.
Preventing weight gain. and promoting physical activity
The results using data on physical
activity at follow-up were moreconsistent. Four studies found that alarge amount of physical activity or exer-cise (Rissanen et al., 1991; Williamsonet al., 1993; Haapanen et al., 1997a;Barefoot et al., 1998) at follow-up wasassociated with less weight gain. Only
Heitmann et al. (1997) did not find suchan association.
Many studies used data on physicalactivity from both baseline and follow-up.An increase in physical activity wasassociated with less weight gain in sevenstudies (Owens et al., 1992; Williamson etal., 1993; Taylor et al., 1994; Haapanen etal., 1997a; Coakley et al., 1998; Thune etal., 1998; Guo et al., 1999; Fogelholm etal., 2000a). Two studies did not find anyassociation between changes in physicalactivity (Bild et al., 1996) or in televisionand video watching (Crawford et al.,1999) and weight change. ln one study
(Fogelholm et al., 2000a), increased butnot decreased physical activity was asso-ciated with weight change. French et aL.
(1999a) did not find an associationbetween the cumulative duration ofincreased physical activity (annual record-ing) and weight change.
Bath studies with data on only vigorousexercise (Barefoot et al., 1998; Coakleyet al., 1998) found an inverse associationbetween exercise and weight change.
However, the different types and intensi-ties of physical activity cannat be com-pared from these data. The two studiesusing data on television watching yieldedcontradictory results (Coakley et al.,1998; Crawford et al., 1999).
The findings that a larger amount ofphysical activity, assessed at the end offollow-up, was associated with lessweight gain may be interpreted in threedifferent ways: first, physical activity mayreally prevent weight gain; second, lessweight gain may lead to better exerciseadherence; third, participation in physicalactivity may be a proxy for a generallyhealthier lifestyle or psychological profile
(e.g., better self-regulation).
The studies cited above did not
generally include data that would allowcalculation of the level of energy
expenditure associated with prevention
of weight gain. Data from studiesexamining prevention of weight relapseafter prior weight reduction suggest thatan increase in weekly energy expendi-
ture of approximately 6300 to 8400kJ/week (1500-2000 kcal/week, corre-sponding to about 1 h of brisk walkingdaily) is associated with improved weightmaintenance (Fogelholm & Kukkonen-
Harjula, 2000). This would correspond taan increase in daily energy expenditureof approximately 10%. However, the
increase in energy expenditure neededfor primary prevention of weight gain
may be slightly lower.
Community interventions forprevention of weight gainOnly a few controlled community inter-ventions have had physical activity as acentral behavioural component and BMIas an outcome (Fortmann et al., 1990;Murray et al., 1990; Brownson et al.,1996; Tudor-Smith et al., 1998). Theseinterventions were designed to decreasemortality and morbidity of cardiovascularheart diseases, but ail had increased
physical activity and decreased preva-lence of obesity as means to achieve thismain objective. Three projects(Heartbeat Wales (Tudor-Smith et al.,1998), the Minnesota Heart Health
Program (Murray et al., 1990; Kelder etal., 1993; Luepker et al., 1994; Jeffery etal., 1995) and the Stanford Five CityProject (Fortmann et al., 1990; Taylor etal., 1991; Young et al., 1996)) includedbath intervention and control communi-ties, whereas the Bootheel Heart HealthProject (Brownson et al., 1996) had thestate as a comparison area. The durationin the interventions was 4-7 years. Thesubjects were obtained by random
cross-section al sampling at the begin-
ning and the end of the follow-up
(Brownson et al., 1996; Tudor-Smith etal., 1998) or through a combination of
cohort and independent cross-sectionalsurveys (Fortmann et al., 1990; Murrayet al., 1990).
These projects based their interven-tion on widespread education alapproaches, that is, face-to-face coun-selling by health professionals and
peers, and use of mass media (televi-sion, radio, newspapers, print materials).Moreover, the use of social support(organized groups, such as walkingclubs), physical activity contests, opinionleaders and models, and risk-factorscreening were common ta these inter-ventions. Changes in the physical environ-ment (e.g., building of walking and fitnesspaths) were reported in one project only
(Brownson et al., 1996), whereas policychanges, with speciallabelling of foods ingrocery stores and restaurants, weredescribed in two interventions (Kelder etal., 1993; Tudor-Smith et al., 1998).
Out of the four projects, two
(Brownson et al., 1996; Tudor-Smith etal., 1998) did not detect any significanteffect of intervention on physical activity,although there was a tendency forincreased physical activity in the inter-vention areas of the Bootheel Heart
Health Project (Brownson et al., 1996).The residents of the intervention commu-nities of the Minnesota Heart Health
Study were somewhat more physicallyactive (self-reported) at the end of thefollow-up (Kelder et al., 1993), an
increase apparently due ta an increasein activities of low intensity. ln theStanford Five-City Project, the interven-tion had a positive effect on physicalactivity in the independent, cross-sec-tional samples, but not in the cohort sur-vey (Fortmann et al., 1990; Young et al.,1996). The observed increase was
seemingly due to increased amounts ofdaily usual activities, rather than to vigor-ous exercise (Young et al., 1996).
Although the results on physical activ-ity were somewhat positive in mostprojects, the effects on body weightchange were disappointing. Threeprojects did not find any effect of
45
IARC Handbooks of Cancer Prevention, Volume 6: Weight Control and Physical Activity
intervention on BMI (Jeffery et al., 1995;Brownson et al., 1996; Tudor-Smith etal., 1998). ln the Stanford Five-City
Project, BMI increased less in the treat-ment than the control communities, butthis effect was observed only by usingcross-sectional, independent surveys
(Taylor et al., 1991).Despite the fact that a majority of
cross-sectional and observation alstudies have shown that high physicalactivity is associated with smaller weightgain, the success of community studiesin preventing weight gain was not
very good. The failure to show clearintervention effects could be due tomethodological problems. Multifacetedinterventions are difficult to evaluate ingeneral and methods of assessing phys-ical activity in large groups are quitecrude and imprecise (Wareham &Rennie, 1998). Moreover, favourable
secular trends in dietary choices as weilas in smoking cessation may not onlydilute intervention effects but also
confound the effect of physical activity inprevention of weight gain.
Another obvious reason for theabove discrepancy is that physical
activity and energy expenditure in theintervention communities did notincrease enough ta counterbalance
secular changes in food intake and dailyactivity (Fogelholm et al., 1996a). ln themost successful intervention (TheStanford Five-City project; Taylor et al.,1991) the difference in estimated dailyenergy expenditure between the inter-vention and control communities was250 kJ/day (60 kcal/day), a weekly dif-ference of 1750 kJ (420 kcal). This ismuch less than has been associatedwith prevention of weight regain
(Fogelholm & Kukkonen-Harjula, 2000).Moreover, it is probable that the threeother cam munit y interventions were
even less successful in increasing totalenergy expenditure. There are severalpotential explanations for the difficulty inincreasing physical activity in interven-tion communities:
46
. The focus has been too much on
tradition al physical activity, ratherthan usual daily activities (lifestyleactivity). The same problem is alsoseen in controlled obesity treatmenttrials. It is likely that large populationsegments may more readily acceptincreased lifestyle activity than morestructured exercise training.
. There was too little priority for physi-cal activity in the interventions. Ali
interventions cited above had adecrease in cardiovascular diseasemortality and morbidity as primaryobjective. This meant that theapproaches were very broad and
physical activity was just one focus ofthe intervention plan.
. The interventions were too general
and hence important subgroupswere lost. For instance, Jeffery et al.
(1995) noted that the interventioneffects were more clearly seen inresidents with elevated serum
cholesterol concentration or a historyof obesity-related disease. Other
potential subgroup targets for physi-cal activity interventions could bepeople of lower social status,minority groups and older adults.
. A high-profile health promotion
programme extended even to thecontrol area (Luepker et al., 1994;
Tudor-Smith et al., 1998). The inter-vention and control communities
were not isolated, both areas being
targets of health promotion through
mass media and from physiciansand other health professionals. If theeducational environment is alreadysaturated with health promotion
mate rial, any additional efforts mayhave only marginal effects (Jeffery etal., 1995).
. Ali interventions had a strong
emphasis on education, their basicassumption being that increasingthe level of knowledge about obesity-related risks; dietary choices
and exercise behaviour would enablepeople to improve weight
maintenance (Jeffery et aL., 1995).Only the Bootheel Heart Health
Project reported deliberate efforts tochange the physicaJ environ ment by
construction of walking and fitnesspaths (Tudor-Smith et al., 1998).
Prevention of weight regainafter prior weight reductionThe challenge in weight reduction is notreally to Jose enough weight, but ratherto maintain the reduced weight. Most
studies show very poor weight mainte-
nance, regardless of the technique usedto reduce body weight (Glenny et al.,1997). The role of physical activity inprevention of weight regain was studiedin the review by Fogelholm andKukkonen-Harjula (2000) of both obser-vational studies and randomized clinicalinterventions. The main results aresummarized below.
A total of 19 non-randomized weight-reduction interventions with an observa-tional follow-up were reviewed. Theduration of the follow-up was typicallybetween one and three years. Most ofthe studies used a retrospectivequestionnaire or an interview ta assessphysical activity. Only Schoeller et al.(1997) measured total activity level bythe doubly labelled water technique,
focusing on vigorous exercise, ratherth an total physical activity.
The results from the above studieswere quite consistent: a total of 12 stud-ies found that a large amount of physicalactivity at the follow-up measurementwas associated with less weight regainafter weight reduction. Four studies usedthe change in physical activity frombaseline (immediately after weight
reduction) ta the end of the follow-up:they ail reported that increased physicalactivity was associated with a sm allerweight regain. Using only baseline (afterweight reduction) data on physical activ-ity, however, gave less consistent
results: Schoeller et al. (1997) found thatmore physical activity was associatedwith better weight maintenance,
Preventing weight gain and promoting physical activity
Figure 23 Bike to Work Day: promotion of physical activity at the Nationallnstitute ofEnvironmental Health Sciences (NIEHS) in the United States
although McGuire et al. (1999) did notfind such an association. Jeffery et al.(1984) reported that physical activityimmediately after weight reduction, butnot one year later, was associated withless weight regain at two years' follow-up.
Eight randomized interventions withexercise and control groups and aprospective follow-up of at least one
year's duration (Perri et al., 1986; Sikandet al., 1988; King et al., 1989; Pavlou etal., 1989; van Dale et al., 1990; Skenderet al., 1996; Wadden et al., 1998; Winget al., 1998) were reviewed (Table 17).The duration of weight reduction variedbetween eight weeks and 12 months.
Three studies used a very low-energy
diet (Sikand et al., 1988; Pavlou et al.,1989; van Dale et al., 1990) during theweight-reduction phase, while the otherstudies used a more conventional dietwith restricted energy intake. Only Perriet al. (1986) reported use of behaviourtherapy. Ali studies used aerobic
exercise (walking or ergometer cycling)with a target duration of approximately
1.5 ta 3 h/week. ln addition, Wadden etal. (1998) had one group with strengthtraining.
Only one study (Pavlou et al., 1989)found clearly that exercise training dur-ing weight reduction led to less weight
gain during the follow-up th an in non-
exercising groups. Sikand et al. (1988)reported a similar but non-significant dif-ference. King et al. (1989) found thatweight regain was smallest in exercisingsubjects randomized to supportive tele-phone contacts during the follow-up.However, those exercising subjects whowere randomized to no extended supportshowed a tendency ta regain even moreweight than the diet-only subjects. vanDale et al. (1990) reported better weightmaintenance in one physical exercisegroup (N = 5), but the finding was appar-ently caused by one outlier. ln contrast tathe above results, four studies did notfind exercise training to improve mainte-nance of reduced body weight (Perri etal., 1986; Sikand et al., 1988; Wadden etal., 1998; Wing et al., 1998).
Very few studies (Perri et al., 1988;Leermakers et al., 1999; Fogelholm etal., 2000b) have used a design with ran-domization to exercise and controlgroups after weight reduction (Table 18).Perri et al. (1988) used several weight-maintenance techniques, including aero-bic exercise in two groups (men andwomen). Ali groups participating in thesix-month weight-maintenance interven-tion had less weight gain compared withthe controls, who were not contactedafter the weight reduction. Nevertheless,the exercise groups did not succeed any
better or worse than the other weight-
maintenance groups. Leermakers et al.
(1999) randomized 67 subjects (menand women) into exercise-focused andweight-focused groups after a six-monthweight-reduction period. The exercisingsubjects met bi-weekly in supervised
exercise session and were also trainedin relapse prevention strategies to avoidor cope with lapses in exercise. The
weight-ocused group learned problem-solving for weight-related difficulties,without emphasis on physical activity.During the unsupervised follow-up (sixmonths), the exercise-group gained
more weight th an the weight-focused
group. Finally, in the study of Fogelholmet al. (2000b), weight-reduced, but stilloverweight or obese, premenopausal
women were randomized into control,moderate walking (target activity energyexpenditure 4.2 MJ/week (1000kcal/week)) and heavy walking (8.4MJ/week (2000 kcal/week)). Ali groupsreceived diet counselling. Comparedwith the end of weight reduction, weight
regain at the two-year follow-up was 3.5
(95% confidence interval 0.2-6.8) kgless in the moderate walking group th anin control subjects. The heavy walkinggroup did not differ from the contrais.
Inadequate amounts of physical activ-ity may help to explain why it has beenso difficult ta find an effect of physicalactivity on weight maintenance in c1inicaltrials. The weekly amount of prescribedexercise in the randomized trials variedfrom 80 min to 300 min, which corre-sponds ta an increase in weekly energyexpenditure by 2300 to 8800 kJ (560 ta2100 kcal). However, adherence to theexercise prescription is much less than100%, and in particular long-terrn adher-ence may be poor.
According to four studies (Hartman etal., 1993; Ewbank et al., 1995; Schoelleret al., 1997; Jakicic et al., 1999), the esti-mated difference in energy expenditurefrom physical activity between the high-est and the lowest exercise group wasmore th an 5500 kJ/week (1300
47
& 1~i
.~~
, Il ø
r¡
AS
-.. .
.-
., .
, .~
- :"
- .
- .
h.. . ~ Il ~
1 ;¡ ;0 0 :i
Ref
eren
ceSu
bjec
tsW
eigh
t red
uctio
n tr
ial
Exe
rcis
e pr
escr
iptio
nFo
llow
-up
Res
ults
i~de
sign
(m
eth(
)d,a
mou
nt)
0 "" (JPe
rri e
t al.,
198
614
M, 7
6 W
20
wk.
BT
onl
y, B
T +
EX
.4
x 20
min
aer
obic
EX
wee
kly
18 m
o, in
clud
ing
6 m
oW
t reg
ain
was
sim
ilar
in B
T (
3.1
kg)
and
S. 0M
ean
wt l
oss
9.4
kg.
mai
nten
ance
sup
port
BT
+ E
X (
3.3
kg)
grou
pso. '"
by m
ail a
nd p
hone
. 67
(" ~measured (74%)
-0 eiSi
kand
et a
l., 1
988
30W
4 m
o. V
LED
onl
y, V
LED
+ E
X.
Aerobic EX, 2 supervised
24 m
o. 2
1 m
easu
red
Wt r
egai
n te
nded
to b
e le
ss in
EX
.. CD
Mea
n w
t los
s 19
.8 k
g.w
eekl
y se
ssio
ns (
abou
t 60-
90(7
0%).
subj
ects
(58
% v
s. 9
6%)
~ õ'm
in/w
k)? 2f
Kin
g et
al.,
198
910
3 M
12 m
o. D
iet o
nly,
EX
onl
y.3
x 40
-50
min
bris
k w
alki
ng12
mo.
Ran
dom
ized
into
2-y
wt r
egai
n w
as s
mal
lest
(17
%)
in E
XE 3
Mea
n w
t los
s 6.
0 kg
.w
eekl
y +
enc
oura
gem
ent t
osupport contacts by mail
subj
ects
with
mai
nten
ance
sup
port
. EX
CD
incr
ease
life
styl
e ac
tivity
and
phon
e vs
no
cont
act.
with
out s
uppo
rt g
aine
d 71
% a
nd th
e0
(120-150 min/wk)
72 m
easu
red
(70%
); 4
8di
et g
roup
s 41
-42%
of w
t los
s.I~
in m
aint
enan
ce s
uppo
rt.
IiPa
vlou
et a
l., 1
989
160
M8
wk.
4 d
iffer
ent V
LED
s (4
20-
3 x
90 m
in E
X w
eekl
y, in
clud
ing
18 m
o. 1
10 m
easu
red
EX
gro
ups
rega
ined
abo
ut 1
0% o
f the
1000
kca
l/d).
Die
t onl
y, d
iet +
35-6
0 m
in a
erob
ic E
X p
er(6
9%).
wt l
oss,
whe
reas
the
diet
gro
ups
EX
(4
x 2
grou
ps).
Mea
n w
tsession (270 min/wk)
rega
ined
92%
i~loss 13.3 kg.
I~va
n D
ale
et a
l., 1
990
15 M
, 39
W D
urat
ion
12-1
4 w
k. V
LED
onl
y,A
erob
ic (
2-3
h/w
k) a
nd f
itnes
s18
-42
mo.
36
mea
sure
dln
one
stu
dy, E
X im
prov
ed w
tIi
VLE
D +
EX
. Mea
n w
t los
s 12
.2 k
g. (
2 h/
wk)
trai
ning
(24
0-30
0(6
7%).
mai
nten
ance
at 4
2 m
o, b
ut th
e9!
min
/wk)
diffe
renc
e w
as a
ppar
ently
cau
sed
by;p u
one
outli
er. N
o ot
her
effe
cts
of E
X w
ere
;;.re
port
ed f
or th
e ot
her
two
stud
ies.
~S
kend
er e
t al.,
199
6 66
M, 6
1 W
12
mo.
Die
t onl
y, E
X o
nly,
die
tW
alki
ng; t
arge
t goa
l 5 x
45
12 m
o. 6
1 m
easu
red
Wt r
egai
n w
as s
imila
r in
die
t + E
X v
s.+
EX
. Mea
n w
t los
ses
6.8,
2.9
,min/wk (225 min/wk)
(48%
).di
et o
nly
grou
ps. E
X o
nly
lost
and
8.9 kg.
rega
ined
less
.
Wad
den
et a
l., 1
998
99 W
48 w
k. A
erob
ic E
X +
die
t, st
reng
th2-3 weekly sessions. Aerobic
12 m
o. 7
7 m
easu
red
EX
did
not
affe
ct m
aint
enan
ce o
f wt
trai
ning
+ d
iet,
aero
bic
EX
+=
ste
p ae
robi
cs; s
tren
gth
=(7
8%).
loss
.st
reng
th tr
aini
ng +
die
t, di
et o
nly.
Uni
vers
al G
ym o
r C
ybex
Mea
n w
t los
s 15
.6 k
g.eq
uipm
ent;
com
bina
tion
= 4
0%ae
robi
c, 6
0% s
tren
gth
(120
-180
min
/wk)
.
Win
g et
al.,
199
832 M,
6 m
o. C
ON
, die
t onl
y, E
X o
nly,
Bris
k w
alki
ng e
tc.,
5 da
ys/w
k,18
mo.
129
mea
sure
dE
X d
id n
ot a
ffect
mai
nten
ance
of w
t12
2Wdi
et +
EX
. Mea
n w
t los
ses
1.5,
targ
et e
nerg
y ex
pend
iture
(84%
).lo
ss.
9.1,2.1,10.3 kg.
6.3
MJ
(150
0 kc
al)
per
wk.
Abb
revi
atio
ns: B
T, b
ehav
iour
al th
erap
y; C
ON
, con
trol
sub
ject
s (n
o tr
eatm
ent)
; EX
, exe
rcis
e; M
, men
; mo,
mon
th(s
); P
A, p
hysi
cal a
ctiv
ity; V
LED
, ver
y-Io
w-e
nerg
y di
et; W
,
wom
en; w
k, w
eek(
s) w
t, w
eigh
t
Preventing weight gain and promoting physical activity
Reference Subjects
Perri et al., 1988 26 M, 97 W
Leermakerset al., 1999
13 M,54 W
Fogelholm et al.,2000
85W
Weight reduction Maintenance intervention Follow-up Results(method, amount)
12 mo. 91measured (74%)
Ali 4 conditions withmaintenance supportyielded better long-term wt loss th an BTalone. EX did notsignificantly affectthe results
BT. 12.4 kg in 20wks
6 mo. Extended therapistcontact (C) vs C and socialinfluence (S) vs C and 4 x20 min aerobic EX weeklyvs C, S and EX vs nomaintenance support
6 mo. 48completed (72%)
EX subjects gainedmore (4.4 kg) th an the
wt-focused subjects(0.8 kg) during mo 6to 12.
Diet + BT, 8.8 kgin 6 mo.
6 mo. EX vs wt-focused.EX = 150 min/wk, biweeklysessions, contingencies,
relapse prevention training.57 (85%) completed
24 mo. 74
measured (87%)The mean wt regainalter WR was 8.3 kg.Compared with theend of WR, wt regainat the end of follow-upwas 3.5 (95% Ci 0.2-
6.8) kg less in EX-1vs CON.
VLED, 13.1 kgin 3 mo.
9 mo. Randomized intowalking (2 groups, EX-1
= target energy expenditure4.2 MJ/wk, EX-2 = 84MJ/wk) and CON. Alireceived diet instruction.
Abbreviations: BT, behavioural therapy; Ci, confidence intervals; CON, control subjects (no treatment); EE, energy expenditure;EX, exercise; M, men; mo, monlh(s); VLED, very-Iow-energy diet; W, women; WR, weight reduclion intervention; wt, weight
kcal/week), but less than 8400 kJ/week
(2000 kcal/week). The difference inyearly weight regain (high versus low
exercise groups) in the above studieswas 5 ta 8 kg. Hence, it seemed that anincrease in energy expenditure of physi-cal activity of approximately 6300 to8400 kJ/week (1500-2000 kcal/week,corresponding ta 1 h of brisk walking
daily) was associated with improved
weight maintenance. This is more thanmost randomized trials aimed at, andcertainly more th an the exercisers actu-
ally achieved. Keeping up increased reg-ular exercise is believed to be particu-larly problematic among obese subjects,who may have both physiological andpsychological barriers to physical activity
(Fogelholm & Kukkonen-Harjula, 2000).Ali randomized trials used traditional
structured training prescription with
walking, jogging or ergometer cycling as
the modes of exercise. Only King et al.(1989) encouraged subjects also toincrease daily lifestyle activity. Since theintroduction of health-related exercise
(Pate et al., 1995), interest in Iifestyleactivity (with several short bouts of exer-cise daily) has increased, but few groupshave studied the effects of lifestyle activity
(Andersen et al., 1999; Dunn et al.,1999) or of multiple short-bout exercise(Jakicic et al., 1999) on weight change inoverweight persons. None of these stud-ies found any statistically significant dif-ference between the effects of differentkinds of activity on weight.
Some groups have studied differentstrategies to improve adherence to exer-cise programmes. Three papers have
reported 'that adherence to a home-based exercise programme is at least asgood as a supervised group programmeamong overweight persans (King et al.,
1991; Perri et al., 1997; Jakicic et al.,1999). Exercise prescribed in multipleshort bouts rather th an as one continu-ous daily bout may or may not improveexercise adherence (Jakicic et al., 1995,1999). Although one might suppose thatadherence would be easier for a lifestyleactivity than for a more fixed exerciseregimen, two studies (Andersen et al.,1999; Robinson, 1999) found adherenceto be equal for both approaches.
How to increase physicalactivityThe first US Surgeon General's Reporton Physical Activity and Health (UnitedStates Department of Health and HumanServices, 1996) has established theimportance of the overall physical activityand health agenda. It is not known towhat extent it will be feasible to integratesystematic and cost-effective exercise
49
IARC Handbooks of Cancer Prevention, Volume 6: Weight Control and Physical Activity
Figure 24 Organized walking day for NIEHS staff members and family
counselling into routine primary care andother health services. It is also not yetclear what effects might be achieved bymass-reach, ubiquitous public healthstrategies that offer 'passive' protection
ta populations by creating (or recreating)environments in which physical activity isa natural and enjoyable part of people'slives.
Trials of interventions to increase
physical activity typically lead to modestinitial changes in behaviour and anychanges tend not to be maintained afterthe intensive initial intervention phase.
Controlled intervention trials in health-care settngs that yielded the strongest
and best-maintained effects onbehaviour have revealed severalimportant elements, including multipleand continuing contacts with participantsand multiple behavioural interventioncomponents (Simons-Morton et al.,1998). For such individual or small-groupinterventions, the most effectiveprogramme elements appear ta be theuse of structured behaviour-change
techniques; educational, health-riskappraisal and verbal persuasion
methods have been found ta be farless effective (Dishman & Buckworth,1996).
Workplace, community and mass-media intervention studies have typicallyfound modest or no actual effects onbehaviour and, where it has been
assessed, poor maintenance of behav-
50
ioural changes (Dishman et al., 1998;Marcus et al., 1998).
The conduct of physical activityintervention trials on which to baselarge-scale, comprehensive strategieshas inherent scientific difficulties. Meta-analyses and qualitative reviews ofpublished studies have identifiedseveral areas of methodological limita-tion. These include lack of standard-ized outcome measures, lack of rigor-ous experimental controls and compro-mises in the implementation of inter-ventions (Dishman et al., 1998).
Studies that meet rigorous methodolog-ical criteria and that demonstrate
strong and sustained effects on physi-cal activity behaviour are few. However,behavioural scientists, epidemiologists,exercise and sport scientists andothers are developing improved, stan-dardized and objectively validatedmeasures of physical activity behav-iours and are applying these in popula-tion studies (Sallis & Saelens, 2000).New studies of physical activity deter-minants, including environ mental influ-ences, are being developed (Baker etal., 2000; Owen et al., 2000). Particularissues for higher-risk or traditionallyneglected groups are being identifiedand addressed systematically (Taylor etal., 1998; Ainsworth, 2000; Ainsworth etal., 2000). Trials of innovative
approaches to increasing energyexpenditure through incidental and
lifestyle activities are under develop-ment (Dunn et al., 1998).
The major need is to develop evi-dence-based mass-reach interventions,along with environmental and policychanges that can be demonstrated to
have a positive impact on rates of partici-pation in physical activity (Jebb & Moore,1999; Sallis et al., 1998). For example,there are now opportunities to conducttrials of mass-reach behavioural-changeservices that use combinations of tradi-tional broadcast media with the newcapacities provided by the Internet andother information technology innova-
tions. Such strategies can potentiallyprovide automated, individually tailoredphysical activity assessments andstructured, interactive advice to largenumbers of people at very low cost(Marcus et al., 1998).
It may be helpful for interventions tafocus on sedentary behaviour as an
entity in its own right (Jebb & Moore,1999; Owen et al., 2000). Prolongedperiods of sedentary behaviour at workmay in future be regarded as an occupa-tional health risk.
Trials of interventions to influence
physical activity have focused on indi-viduals. The challenge is to influencewhole populations effectively. Theextensive social changes and strategiesneeded to promote physical activity willrequire strong interactions between
science, advocacy and public healthpolicy. Environmental and policyinitiatives require research on new waysto assess putative macro-Ievelinfluences on physical activity. Suchenviron mental and policy interventionsinclude, for example, the provision ofwalking and cycling paths, restrictionson automobile access to city centresand provision of showers and changingfacilities at workplaces. Systematictrials are needed to demonstrate theextent ta which such changes caninfluence people's choice to be moreactive (Sallis et al., 1998).
Lessons to be learned fromother successful public health
campaignsCampaigns that have been successful indealing with public health problems
include those to discourage smoking anddrink-driving or to promote immunizationand the wearing of seatbelts. Analyses ofthese campaigns have helped to identifyfeatures that can be applied in publichealth interventions to control obesity
(Egger & Swinburn, 1997). For example,it appears that programmes which
involve government, the community, thefood industry and the media, and whichare of long duration, lead to positive andsustainable change (WHO Consultationon Obesity, 1998).
Public health programmes to preventweight gain are unlikely ta achieve thesame spectacular rates of success asthose associated with the control ofinfectious disease. Unlike the case ofpathogens, it is not feasible to rem ovetotally the causes of obesity. Nor is it asimple process ta isolate and manageexposure to major disease-promoting
factors in the way that the control ofsmoking and hypertension has con-tributed to the reduction in rates ofchronic heart disease. Overweight, the
consequence of energy imbalance, ismore tightly controlled physiologically
Prevenling weighl gain and promoling physical aclivily
than other risk factors are and is subjectta man y environmental influences thatshape food choices and physical activitybehaviours (Figure 25). Nevertheless,
with concentrated efforts, particularlyalong the lines recommended in Chapter10, successes in weight gain preventionand in physical activity promotion can beachieved.
There are good reasons to believethat weil conducted preventive initiativeswith adequate resources will succeed.For example, large numbers of people inmany populations do maintain habits ofregular physical activity and maintain ahealthy body weighl. While this is moreIikely in higher socioeconomic groups, itshould nevertheless be seen as realisticand achievable. Regular physicalactivity and maintaining a healthy bodyweight will be more possible if peoplehave supportive environments. Where
governments and community bodiesprovide facilities and settngs for physi-cal activity, or where there are weilorganized programmes with adequateresources, people are better able tamaintain regular activity. For societies toprovide such support and services,significant commitments of funding andweil developed policies and organiza-
tional systems are required. Given theextent of cancer-related risk and other
health risks associated with overweightand inactivity including heart diseaseand diabetes, such serious commit-
ments should be made.
Figure 25 Keep on movìng! A person loses
25% of his or her lean body mass and 75% ofhis or her fat when losing weight through
reduction of energy intake alone. Weight lossthat is achieved with a cambination of dietaryrestriction and physical activity is moreeffective !
For maintenance of desirable body weight amaintenance level of energy intake alone withphysical activity is recammended ta preservelean body mass and muscle tone.
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