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

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X d

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nten

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. Mea

n w

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(84%

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ss.

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atio

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al th

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ON

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sub

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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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