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Public Health Nutrition: 7(1A), 123–146 DOI: 10.1079/PHN2003585
Diet, nutrition and the prevention of excess weight gain and
obesity
1, 2 3 4
BASwinburn *, I Caterson , JC Seidell and WPT James
1Physical Activity and Nutrition Research Unit, School of Health Sciences, Deakin University, Melbourne, Australia:
2Faculty of Medicine, University of Sydney, Sydney, Australia: 3Free University of Amsterdam, Amsterdam,
The Netherlands: 4International Obesity Task Force, London, UK
Abstract
Objective: To review the evidence on the diet and nutrition causes of obesity and to
recommend strategies to reduce obesity prevalence.
Design:Theevidenceforpotentialaetiologicalfactorsandstrategiestoreduceobesity
prevalencewasreviewed,andrecommendationsforpublichealthaction,population
nutrition goals and further research were made.
Results: Protective factors against obesity were considered to be: regular physical
activity (convincing); a high intake of dietary non-starch polysaccharides (NSP)/fibre
(convincing);supportivehomeandschoolenvironmentsforchildren(probable);and
breastfeeding (probable). Risk factors for obesity were considered to be sedentary
lifestyles (convincing); a high intake of energy-dense, micronutrient-poor foods
(convincing); heavy marketing of energy-dense foods and fast food outlets
(probable); sugar-sweetened soft drinks and fruit juices (probable); adverse social
and economic conditions—developed countries, especially in women (probable).
A broad range of strategies were recommended to reduce obesity prevalence
including: influencing the food supply to make healthy choices easier; reducing the
marketing of energy dense foods and beverages to children; influencing urban
environments and transport systems to promote physical activity; developing
community-wide programmes in multiple settings; increased communications about
healthy eating and physical activity; and improved health services to promote Keywords
breastfeeding and manage currently overweight or obese people. Public health
Conclusions: The increasing prevalence of obesity is a major health threat in both Overweight
low- and high income countries. Comprehensive programmes will be needed to turn Obesity
the epidemic around. Evidence-base
This review paper has been structured to provide an the authors and Expert Consultation members. The
overview of the likely aetiological factors in the evidence judgments were based on the framework and
development of weight gain and obesity, to propose definitions used by the World Cancer Research Fund and
related population nutrient goals and content areas for American Institute for Cancer Research in their review on
1. The evidence in that report was rated as
food-baseddietaryguidelines,andtoevaluatesomeofthe diet and cancer
potential food and diet related intervention strategies that convincing, probable, possible or insufficient for a
might help to attenuate and eventually reverse this global positive, a negative or no relationship between the
epidemic. The process involved Medline searches on variable and cancer. However, because their outcome of
relevant topics determined by the authors and the interest was cancer, the framework mainly centred on
participants in the Joint WHO/FAO Expert Consultation epidemiological studies. In the current review, random-
on diet, nutrition and the prevention of chronic diseases ised clinical trials were given the highest ranking with
(Geneva, 28 January–1 February 2002). Recent reviews consistent results from several trials constituting convin-
andkeypapersweresought,butthisdidnotinvolveafull cing evidence. This is particularly important in the
systematic review on each topic. relationship between diet and obesity because of the
The level of evidence that a dietary factor could be major methodological problems of dietary underreport-
involved in the promotion of or protection against the ing. Obese people tend to underreport more than lean
development of obesity was assigned on the basis of the people and the underreporting may be the greatest for
2,3
evidence review and the weighting of this evidence by high fat and high carbohydrate foods . Another difficulty
*Corresponding author: Email swinburn@deakin.edu.au qTheAuthors 2004
https://doi.org/10.1079/PHN2003585 Published online by Cambridge University Press
124 BASwinburn et al.
aroseinratingevidenceinrelationtosomeofthepotential Brazil is an example of a country with well-
environmental causes of weight gain. For environmental documented changes in obesity prevalence as it under-
factors, more associated evidence and expert opinion had goes rapid nutrition transition. There has been a rapid
to prevail because of the absence of direct studies or trials increase in obesity where the prevalence among urban
4
in the area . menwith high incomes is about 10%, but still only 1% in
It is important to note that this review on obesity has rural areas. Women in all regions are generally more
not covered the energy expenditure side of the energy obese than men and the prevalence for those on low
balance equation in any depth. Physical activity is at least income is still increasing. However, the rate of obesity
as important as energy intake in the genesis of weight among women with high income is becoming stable or
15
gain and obesity and there are likely to be many even declining .
interactions between the two sides of the equation in The standard definitions of overweight (BMI $ 25
terms of aetiology and prevention. The role of physical kg/m2) and obesity ($30kg/m2)havebeenmainly
inactivity in the development of obesity has been well derivedfrompopulationsofEuropeandescent8.However,
described5 and a recent report from the US Center for in populations with large body frames, such as Poly-
16
Disease Control and Prevention summarises the evidence nesians, higher cut-off points have been used .In
base for a variety of interventions to increase physical populations with smaller body frames, such as Chinese
6 17
activity at the population level . Also, a thorough review populations, lower cut-off points have been proposed
of weight control and physical activity has recently been and studies are being undertaken to evaluate appropriate
18
conducted by the WHO International Agency for cut-off points for a variety of Asian populations .
Research on Cancer and was also used as a basis for Body fat distribution (often assessed by the waist
recommendations on physical activity7. circumference or the waist:hip ratio) is an important
19,20
independent predictor of morbidity . Although this
Current global situation and trends review focuses on weight gain and the development of
overweight and obesity, it is acknowledged that increases
Overview in abdominal fatness (particularly, intra-abdominal fat)
The prevalence of obesity is increasing throughout the pose a greater risk to health than increases in fatness
world’s population. But the distribution varies greatly aroundthehipsandlimbs.Ingeneral,thecausesofweight
between and within countries. In the US, over the past 30 gain and abdominal weight gain are the same and it is the
years, the prevalence of obesity rose from about 12–20% characteristics of the individuals (such as sex, age,
8 menopausal status) that influence the distribution of the
of the population from 1978 to 1990 . The UK has
experienced an increase in the prevalence of obesity from fat that is gained.
8
7%in 1980 to 16% in 1995 . Other countries, such as The
Netherlands, have experienced much smaller increases The nutrition transition
from a low baseline of about 5% in the 1980s to about 8% The increasing westernisation, urbanisation and mechan-
9
in 1997 . In Asia, the prevalence of obesity has rapidly isation occurring in most countries around the world is
increased. In the last 8 years the proportion of Chinese associatedwithchangesinthediettowardsoneofhighfat,
2 8,21
menwithabodymassindex(BMI).25kg/m hastripled high energy-dense foods and a sedentary lifestyle . This
from 4 to 15% of the population and the proportion in shift is also associated with the current rapid changes in
10
womenhasdoubledfrom10to20% .Pacificpopulations childhood and adult obesity. Even in many low income
have some of the world’s highest prevalence rates of countries, obesity is now rapidly increasing, and often
obesity. The proportion of men and women with a BMI coexists in the same population with chronic under-
2 11 21
.30kg/m in Nauru was 77% in 1994 and for Pacific nutrition . Life expectancy has increased due to
people living in New Zealand in the early 1990s the advancement in nutrition, hygiene and the control of
12
prevalence rates were about 65–70% . infectious disease. Infectious diseases and nutrient
The obesity epidemic moves through a population in a deficiency diseases are, therefore, being replaced in
reasonably consistent pattern over time and this is developing countries by new threats to the health of
reflected in the different patterns in low- and high income populations like obesity, cardiovascular disease and
8
countries. In low income countries, obesity is more diabetes .
commoninpeopleofhighersocioeconomic status and in A sharp decline in cost of vegetable oils and sugar
those living in urban communities. It is often first meansthattheyarenowindirectcompetitionwithcereals
22
apparent among middle-aged women. In more affluent as the cheapest food ingredients in the world . This has
countries, it is associated with lower socioeconomic caused a reduction in the proportion of the diet that is
13,14 21
status, especially in women, and rural communities . derived from grain and grain products and has greatly
The sex differences are less marked in affluent countries increased world average energy consumption, although
and obesity is often common amongst adolescents and this increase is not distributed evenly throughout the
22
younger children. world’s population .
https://doi.org/10.1079/PHN2003585 Published online by Cambridge University Press
Diet, nutrition and the prevention of excess weight gain and obesity 125
As populations become more urban and incomes rise, figures underestimated the full direct costs of weight-
diets high in sugar, fat and animal products replace more associated disease because they estimated the costs for
traditional diets that were high in complex carbohydrates the population with BMI . 30kg/m2 and omitted any
21,22 2
and fibre . Ethnic cuisine and unique traditional food burden of lesser forms of overweight (BMI 25–30kg/m ).
habits are being replaced by westernised fast foods, soft A Dutch study suggests the costs attributed to BMI
22 2
drinks and increased meat consumption . Homogenis- 25–30kg/m are three times the cost of BMI .30
232
ation and westernisation of the global diet has increased kg/m . The direct costs of obesity are predominantly
the energy density22 and this is particularly a problem for from diabetes, cardiovascular disease and hypertension.
thepoorinallcountrieswhoareatriskofbothobesityand Indirect costs, which are far greater than direct costs,
14
micronutrient deficiencies . include workdays lost, physician visits, disability pen-
sions and premature mortality which all increase as BMI
33
Health consequences of obesity increases . Intangible costs (impaired quality of life)
Mortality rates increase with BMI and they are greatly have not been estimated, but given the social and
223 psychological consequences of obesity, they are likely to
increased above a BMI of 30kg/m . For example, a
study in US women estimated that among people with a be enormous.
2
BMI.29kg/m ,53%ofalldeathscouldbedirectlyrelated
24
to their obesity . Potentialaetiological factors in relation to obesity in
As obesity has increased over the last 30 years, the populations
prevalence of type 2 diabetes has increased dramatically.
The global numbers of people with diabetes (mainly type The format for identifying potential nutritional causes of
2) are predicted to rise by almost 50% in 10 years—151 obesity at a population level is based on the Epidemio-
25 logical Triad34 where the ‘hosts’ are the general
million in 2000 to 221 million in 2010 . The most potent
predictor for the risk of diabetes, apart from age, is the population, the ‘vectors’ are the foods and nutrients and
23 2
BMI .EvenataBMIof25kg/m theriskoftype2diabetes the ‘environment’ includes the physical, economic, policy
is significantly higher compared to BMI of less than and socio-cultural factors external to the individual.
2 2 Issues were selected based on their relevance to
22kg/m , but at BMI over 30kg/m , the relative risks are
26 approaches to reducing the burden of obesity at a
enormous . Type 2 diabetes is becoming increasingly
prevalentamongchildrenasobesityincreasesinthoseage population level. The evidence summary for identified
groups. This was first reported among the Pima Indians in issues is shown in Table1.
1979 where 1% of the 15–24-year-olds had diabetes
27
(almost all type 2 diabetes) . Now in many populations Host issues
around the world, a substantial proportion of the There are a variety of behaviours and other host factors
teenagers with diabetes have the obesity-associated type that have a potential effect on a population’s level of
28
2 variety . Asian populations appear to develop diabetes obesity. These are, of course, closely linked to the vectors
29
at a lower BMI than other populations . andtheenvironmentsandinmanycasestheissuesmerge
AhighBMIisassociatedwithhigherbloodpressureand and overlap. Issues related to social aspects of eating are
risk of hypertension, higher total cholesterol, LDL- not covered.
cholesterol and triglyceride levels and lower HDL-
cholesterol levels. The overall risk of coronary heart Snacking/eating frequency
disease and stroke, therefore, increases substantially with Whilethere is no one definition of snacking, it is probably
weight gain and obesity23. best to consider the content of snack foods and the
Gall bladder disease and the incidence of clinically increased eating frequency that snacking promotes as
23 35
symptomatic gallstones are positively related to BMI . separate issues . There is evidence from the US that
There is evidence to suggest increased cancer risk as BMI snacking prevalence (i.e. occasions of snacking) is
increases, such as colorectal cancer in men, cancer of the increasing, the energy density of snack foods is increasing
endometrium and biliary passage in women, and breast 36
andthecontributiontototal energy is increasing . Snacks
8,23
cancer in post-menopausal women . Obese people are contribute to about 20–25% of total energy intake in
also at increased risk of gout, sleep apnoea, obstetric and 35
countries like the US and UK . However, there is little
23
surgical complications . evidence that a higher frequency of eating per se is a
potential cause of obesity. Cross-sectional studies tend to
Health care costs of obesity show a negative relationship or no relationship between
37
The direct health care costs of obesity in the US have meal frequency and BMI . Low eating frequency may, of
been estimated to account for 5.7% of total health care course, be a response to obesity rather than a cause.
expenditure in 1995. Comparable figures are somewhat Experimental studies have found mixed results on the
lower than this for other western countries such as France degree of caloric compensation that people make at meal
30 31
(2%), Australia (2%) and New Zealand (2.5%) . These time in response to a prior snack with some studies
https://doi.org/10.1079/PHN2003585 Published online by Cambridge University Press
126 BASwinburn et al.
Table 1 Evidence table for factors that might promote or protect against overweight and weight gain
Evidence Decreases risk Norelationship Increases risk
Convincing Regular physical activity Sedentary lifestyles
High dietary NSP/fibre intake High intake of energy dense foods*
Probable Homeandschoolenvironments that Heavy marketing of energy dense foods*
support healthy food choices for children and fast food outlets
Breastfeeding Adverse social and economic conditions
(developed countries, especially for women)
High sugar drinks
Possible LowGIycemic Index foods Protein content Large portion sizes
of the diet
High proportion of food prepared outside
the home (western countries)
‘Rigid restraint/periodic disinhibition’ eating patterns
Insufficient Increased eating frequency Alcohol
*Energy dense foods are high in fat and/or sugar; energy dilute foods are high in NSP/fibre and water such as fruit, legumes, vegetables and whole grain
cereals.
Strength of evidence: The totality of the evidence was taken into account. The World Cancer Research Fund schema was taken as the starting point but
was modified in the following manner: RCTs were given prominence as the highest ranking study design (RCTs not a major source of cancer evidence);
associated evidence was also taken into account in relation to environmental determinants (direct trials were usually not available or possible).
showing more complete compensation among lean from home and the proportion of food budget spent on
37 42,44,45
people . There is insufficient evidence to support an away from home foods has coincided with the
effect of a higher frequency of eating on obesity or weight increasing prevalence of obesity.
gain. If anything, it is protective against weight gain. The In the US, food prepared away from home is higher in
high energy density of common snack foods, however, total energy, total fat, saturated fat, cholesterol and
maydotheoppositeandpromoteweightgain(seebelow). sodium, but contains less fibre and calcium and is overall
of poorer nutritional quality than at-home food. Also, the
Restrained eating, dieting and binge eating patterns fat content of at-home food has fallen considerably from
Whileadegreeofselectiveorrestrainedeatingisprobably 41%oftotalenergyin1977to31.5%,buttherehasbeenno
needed to prevent obesity in an environment of plenty, change in the fat content of food prepared away from
43.
someindividuals(dieters andnon-dieters) score highly on home(37.6%)
the Restraint Scale and paradoxically may also exhibit These food composition differences and the increasing
38
periods of disinhibited eating . Such individuals appear portion sizes, are likely contributors to the rising
44
to be at risk of dieting–overeating cycles. The concepts prevalence of obesity in the US . Those who eat out
used to define these constructs and the instruments used more, on average, have a higher BMI than those who eat
46
to measurethemcontinuetoevolve,butthestudieswould more at home . The evidence implicating the increasing
suggestthata‘flexiblerestraint’eatingpatternisassociated useoffoodpreparedoutsidethehomeasariskforobesity
with a lower risk of weight gain whereas a ‘rigid is largely limited to the US but this may be extrapolated to
restraint/periodic disinhibition’ pattern is associated with other western countries. It is unknown whether a high
39 40
agreater risk of weight gain . Binge eating disorder and frequency of eating out is associated with obesity or
night eating syndrome41 would be examples of the latter weight gain in other populations, for example, in Asian
pattern. Binge eating disorders are significantly more countries, where eating outside the home may not be a
common in obesity in cross-sectional studies. The risk for weight gain.
relationships between these dietary patterns and weight
gain or obesity is complex with both cause and effect Breastfeeding
relationships likely. Breastfeeding has been suggested as a potential protective
47 and this is
factor against weight gain in childhood
Eating out important because overweight children and adolescents
48
In western countries, the frequency of eating food are at risk of becoming overweight adults . A review by
prepared outside the home is increasing and this is most Butte49 examined 18 studies (6 retrospective, 10
apparent and best documented in the US. In 1970, 26% of prospective, 1 cohort, 1 case–control) published up to
the food dollar in the US was spent on food prepared 1999 with a total of nearly 20,000 subjects. There was a
outside the home. By 1995, it had climbed to 39% and is wide time span (1945–1999) and the definitions of
projected to rise to 53% by 201042,43. This shift towards an breastfeeding and obesity and the length of follow up
increase in the frequency of eating meals and snacks away were all highly variable. Two of the studies found a
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