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International Journal of Epidemiology 2001;30:1136–1137
Commentary: Globalization and the
epidemiology of obesity
J effery Sob al
Th e biom edical roots of epidem iology lead m ost epidem iologists
to exam in e in dividu als as u n its of an alysis, typically in on e
popu lation an d on e place, an d to in terpret th eir fin din gs u sin g
ph ysiological explan ation s. However, com parative epidem iology
is in creasin gly con trastin g th e prevalen ce an d pattern s of
variou s con dition s in differen t places, an d social epidem iology is
em ployin g social scien ce in terpretation s of research fin din gs.
Like m an y oth er fields, epidem iologists are payin g close
atten tion to th e rise in th e prevalen ce of obesity in all parts of
th e world in wh at h as been labelled th e ‘obesity epidem ic’.1,2
Mu ch epidem iological research h as exam in ed h igh levels of
adu lt obesity, an d n ow m ore an alysts are stu dyin g ch ildren ’s
body weigh ts to seek th e precu rsors of overweigh t adu lts an d
exam in e fu tu re adu lt coh orts.
Research by Wan g3 in th is issu e of th e International Journal
of Epidemiology advan ces cu rren t kn owledge abou t obesity in
ch ildren by applyin g stan dardized con sen su s-based m easu res
of body weigh t to relatively recen t cross-section al sam ples in
th ree large n ation s: Ch in a, Ru ssia, an d th e US. Com parative
cross-n ation al research design s4 m ay provide u sefu l in sigh ts
abou t processes in volved in th e ch an gin g prevalen ce of h ealth
Division of Nu trition al Scien ces, Corn ell Un iversity, Marth a Van Ren sselaer
Hall, Ith aca, NY 14853-4401, USA.
con dition s su ch as body weigh t. Wan g3 fou n d obesity an d overweigh t were relatively com m on in US ch ildren wh ile u n derweigh t was rare, th e reverse was tru e of Ch in a, an d Ru ssia stood
between th e oth er two n ation s. Wan g3 also iden tified im portan t
variation s in overweigh t an d u n derweigh t by socioecon om ic
statu s an d ru ral-u rban residen ce, wh ich su ggested addition al
com plexities in th e processes u n derlyin g body weigh t differen ces between th e th ree n ation s. Wan g’s3 research open s th e
door for epidem iologists to in corporate th e con cept of globalization in to th e field.
Cross-n ation al data can be in terpreted in several ways,
in clu din g as eviden ce of globalization .4 Epidem iologists h ave
typically con sidered n ation al differen ces in h ealth an d illn ess as
site-specific cases or as exam ples of a progressive m odern ization
process th at n ation s proceed th rou gh at differen t rates. Rath er
th an con siderin g each n ation as a separate u n it of an alysis,
h owever, an altern ative is to con sider th e world as a global u n it
wh ere overarch in g in stitu tion s an d processes operate. Su ch
global th in kin g h as em erged as an im portan t fram ework in
th e social scien ces,5 an d it wou ld be fru itfu l for epidem iologists
to in corporate globalization in to th eir con ceptu alization s an d
analyses. Little global thinking is currently evident in epidemiology,
with som e exception s in con siderin g globalism in occu pation al
h ealth , in fectiou s disease, an d n u trition .6
CHILDHOOD OBESITY AND SOCIOECONOM IC STATUS
Globalization is th e process of worldwide in tegration an d u n ification of previou sly local, n ation al, an d region al ph en om en a
in to global u n its. Globalization in volves m ore th an in tern ation alization or cross-n ation al, cross-cu ltu ral, or cross-popu lation
lin kages. Ach ievem en t of globality m akes n ation s com pon en ts
of a com m on global wh ole rath er th an separate u n its of an alysis
to be com pared in depen den tly. Global govern m en ts, global corporation s, global m edia, global food system s, an d global diseases
becom e th e n ew u n its of an alysis rath er th an separate n ation al,
local, or in dividu al cases. To th e exten t th at obesity represen ts
a worldwide epidem ic, it con stitu tes a global pan dem ic rath er
th an a set of in depen den t occu rren ces in variou s n ation s. Th e
cru cial poin t in th in kin g abou t globality is th at global con dition s
have underlying global causes and also require global interventions.
Global in creases in th e in ciden ce an d prevalen ce of obesity
are grou n ded in th e globalization of Western post-in du strial food
system s an d con su m er cu ltu re th at h as in creasin gly pen etrated
all societies of th e world.5,7 Un derstan din g th e global epidem iology of obesity requ ires an alysis of th e global in stitu tion s
th at m odify caloric in take an d en ergy expen ditu re. Global
corporation s are establish in g in du strialized agro-food system s
in alm ost all n ation s th at will provide con stan t 24 h ou rs a day/
7 days a week/ 365 days a year con su m er access to virtu ally
u n lim ited volu m es of relatively in expen sive calorifically den se
foods to all people in all places at all tim es th rou gh su perm arket,
caterin g, ven din g, takeou t, h om e delivered, drive th rou gh , an d
fast/ sn ack foods.8,9 Oth er global processes provide in creasin gly
u n iversal an d relatively in expen sive tran sportation , com m u n ication , an d oth er activity-sparin g system s th rou gh au tom obiles,
television , an d en ergy-savin g com pon en ts of th e bu ilt en viron m en t th at m in im ize ph ysical activity levels for a growin g proportion of people worldwide.8,9 Global food system s an d global
veh icles, applian ces, an d m ass m edia are th e u n derlyin g cau ses
of in creases in global obesity.6,9
To fu lly u n derstan d th e globalization of obesity, epidem iologists n eed to m ove beyon d biology an d beyon d beh aviou rs
to exam in e collective social, econ om ic, an d political stru ctu res
an d cu ltu ral ch an ges rath er th an focu sin g on ly on in dividu al
ph ysiology an d person al ch aracteristics. Global valu es, corporation s, an d politics tran sform th e m aterial con dition s of
life so th at ch ildren an d adu lts eat m ore an d are less active,
leadin g to global in creases in obesity. In clu din g qu estion s on
n ation al su rveys th at ask abou t processed food con su m ption
an d television viewin g can provide in sigh ts in to th e u n derlyin g
processes in th e globalization of obesity better th an addition al
batteries of stan dard dem ograph ic an d h ealth qu estion s. In vestigation of globalization m ay also em ploy m u lti-level con textu al
an alyses, exam in in g n eigh bou rh ood or n ation al fast food
fran ch ises an d obesity levels or an alysin g television access in
com m u n ities an d m ean body weigh ts.
1137
Som e n ation s su ch as th e US are alm ost com pletely globalized
in th eir food an d activity pattern s for all social strata. Oth er
cou n tries like Ru ssia an d Ch in a are cu rren tly less th an fu lly
globalized, wh ere h igh er socioecon om ic statu s in dividu als h ave
becom e in corporated in to global system s an d are becom in g
obese while lower socioeconomic status individuals remain localized an d experien ce u n dern u trition . Ru ral-u rban differen ces in
obesity are sm all in th e US,3,10 wh ere globalization approach es
u n iversal pen etration , wh ile th ey rem ain large in cou n tries
su ch as Ch in a an d Ru ssia wh ere ru ral location s h ave n ot been
as com pletely drawn in to global system s. Ch ildren an d adolescen ts ten d to participate in global cu ltu re m ore qu ickly th an
th eir paren ts, an d th erefore you n g coh orts bear watch in g for
th eir in volvem en t in global in stitu tion s th at will sh ape th eir
eatin g an d activity levels an d con sequ en tly th eir body weigh ts.
Th e biom edical basis of epidem iology h as led th e field to
focu s on com parison s of in dividu als an d popu lation s, rath er
th an u n its m ore appropriate to an alysis of globalization su ch
as m arkets or cu ltu res. Th e u sefu ln ess of epidem iological data is
con tin gen t u pon providin g in form ation abou t appropriate u n its.
Obesity in terven tion s som etim es in clu de local an d n ation al
policy ch an ges,2,6 bu t global rath er th an com m u n ity an d federal
pu blic h ealth m easu res are n eeded to adequ ately deal with th e
globalization of obesity.
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