Obesity, diets, and social inequalities
Obesity and type 2 diabetes follow a socioeconomic gradient. Highest rates are
observed among groups with the lowest levels of education and income and in the
socioeconomic factors influence the diet and health of a population. As incomes
drop, energy-dense foods that are nutrient poor become the best way to provide
diets not only cost more but are consumed by more affluent groups. This article
economic insecurity and a failing economic environment.
© 2009 International Life Sciences Institute
Rising rates of obesity in industrialized societies have
been blamed on increased consumption of sweetened
beverages and energy-dense foods.1Published research
has variously linked rising obesity rates in the United
added fats, snacks, beverages, fast foods, and eating away
from home.2One way to change dietary behaviors is by
modifying the obesogenic food environment. Reducing
consumer access to palatable sweet and high-fat foods
seems to be the main goal of many nutrition policies and
Minorities and the poor are clearly at a disadvantage
when it comes to the adoption of healthier eating habits.
Simply put, fats and sweets cost less, whereas many
healthier foods cost more.3Researchers have shown that
and convenience stores as opposed to full-service super-
markets and grocery stores. By contrast, more affluent
areas generally have access to better restaurants, fresher
produce, and more opportunities for physical activity.
Such studies merely demonstrate that socioeconomic
factors, including inequitable access to healthy foods,
have a profound effect on weight and health. It is eco-
nomic deprivation that is obesogenic, and one key pre-
dictor of weight gain may be low diet cost.
The obesity debate in the United States has steered
clear of the complex issue of social class. Instead, much
time has been spent on genetics, physiology, race/
ethnicity, personal responsibility, and freedom of choice.
Some in public health nutrition have adopted the view
that most Americans could follow a healthy diet but
simply choose not to. Attempts to improve population
dietary habits have therefore emphasized the food-choice
behavior of individuals. The emphasis has been on psy-
chosocial factors, self-efficacy, and readiness to change.
The unspoken assumption has been that healthful foods
less of income, have access to a healthy diet. It may be
time to point out that obesity is an economic issue.3,4
Many segments of society have limited resources and are
unable to resist powerful economic forces that are largely
beyond their control.
Americans spend the lowest proportion of dispos-
able income on food (~12%) and have the lowest-cost
food supply in the world.5Until recently,no one seriously
questioned the benefits of low-cost foods or indeed the
freedom to choose.Official recommendations and guide-
lines, including the 2005 Dietary Guidelines for Ameri-
cans, exhorted consumers to “choose” healthful diets as
opposed to unhealthful ones. Other documents recom-
mended that obese consumers replace white bread,
bologna, and mayonnaise with fresh salads, mangos, and
Affiliation: A Drewnowski is with the Center for Public Health Nutrition at the School of Public Health and Community Medicine, University
ofWashington, Seattle,Washington, USA.
Correspondence: A Drewnowski, Center for Public Health Nutrition, University ofWashington, Seattle,Washington, 98195-3410, USA.
E-mail: firstname.lastname@example.org, Phone: +1-206-543-8016, Fax: +1-206-685-1696.
Key words: diet cost, energy density, energy intake, obesity, poverty
Nutrition Reviews® Vol. 67(Suppl. 1):S36–S39
star fruit. The rapid rise in food prices has helped dem-
onstrate that healthier diets are no longer merely a matter
Food choices are made on the basis of taste, cost,
convenience, and, to a lesser extent, healthfulness and
variety.6Refined grains, added sugars, and added fats are
good tasting, readily accessible, and inexpensive. Low-
cost foods and low-cost diets tend to be energy dense and
eating; on the other hand they are preferentially selected
by the low-income consumer.The low cost and high pal-
atability of energy-dense foods – mainly sugars and fats –
along with the easy access to such foods can help explain
why the highest obesity rates are found among the most
disadvantaged groups.3The key variable, however, is not
the macronutrient composition of the diet; rather, what
may predict obesity is low diet cost.7
POVERTY AND OBESITY ARE LINKED
The rates of obesity and type 2 diabetes in the United
States follow a socioeconomic gradient, with the highest
rates observed among racial/ethnic minorities and the
poor.3At the individual level, obesity rates are linked to
low income, low education, minority status, and a higher
incidence of poverty.8Among women, higher obesity
rates tend to be associated with low incomes and low
education; the association of obesity with low socioeco-
nomic status has been less consistent among men.At the
environmental level, obesity rates are higher in lower-
income neighborhoods, legislative districts, and states.8,9
Although obesity rates have continued to increase
steadily in both sexes, across all ages and all races, and at
all educational levels, the highest rates occur among the
most disadvantaged groups. Obesity and food insecurity,
defined as the limited or uncertain availability of nutri-
tionally acceptable or safe foods,also appear to be linked,
at least among female recipients of food assistance
ENERGY-DENSE FOODS COST LESS
Developments in agriculture and food technology have
made energy-dense foods accessible to the consumer at a
very low cost. Figure 1 shows the inverse relationship
between the energy density (kcal/g) of foods and the
energy cost (US$/1,000 kcal). Food prices were obtained
fresh produce was 10 times as much as that of vegetable
oils and sugars.As indicated by the logarithmic scale,the
difference in energy costs between the healthy and
unhealthy foods was several thousand percent. The
energy cost of soft drinks was, on average, 30 cents per
megajoule (MJ), whereas that of orange juice from con-
centrate was 143 cents/MJ.
Fats and oils, sugar, refined grains, potatoes, and
beans provided dietary energy at minimum cost. Dry
foods with a stable shelf life are generally less costly (per
MJ) than perishable meats, fish, dairy products, or fresh
produce. The selection of refined grains, added sugars,
and vegetable fats may represent a deliberate strategy to
save money. Lower food costs may be associated with
more energy-dense diets, and total energy intake may
actually increase.7This means that, paradoxically, it is
possible to spend less and eat more, provided that the
extra energy comes in the form of added sugar and added
fat.3The association between poverty and obesity may be
mediated,in part,by the low cost and high palatability of
energy-dense foods.3In fact,the foods implicated in pro-
moting obesity,like snacks,fast foods,sweets,and refined
grains,are those that provide dietary energy at a very low
The standard dietary advice is to replace fats and
sweets with more fruit, vegetables, whole grains, poultry,
and fish.1However, these more healthful foods are also
more expensive and beyond the reach of many. Some
low-income families limit their food budget to $100 for
four people per week, or less than $4 per person per day.
The only foods that can be obtained for this amount of
money are high in refined grains, added sugars, and
added fats, and the healthful, recommended foods are
separated by an immense gap in energy costs.
Energy Density (kcal/g)
Energy Cost ($/1000 kcal)
2006 retail prices
Figure 1 Relationship between energy density of
selected foods (kcal/g) and energy costs (US$/
1,000 kcal). Food prices from Seattle supermarkets, 2006.
and fats and fresh vegetables and fruit can be several thou-
sand percent, as indicated by the logarithmic scale.
Nutrition Reviews® Vol. 67(Suppl. 1):S36–S39
HEALTHIER DIETS COST MORE
Not only do healthier diets cost more, they are also con-
sumed by more affluent persons. Diet quality in the
United States is very much a function of socioeconomic
status. People who are older, wealthier, and better edu-
cated are both thinner and have better diets than do the
poor. The impact of socioeconomic status variables on
diet quality has normally been ascribed to a higher edu-
cational level or a greater awareness of health issues
esis is that food choices are driven by the relative differ-
ences in cost between high-quality and low-quality foods.
This observation is not restricted to the United States:
similar associations between higher incomes and higher-
quality diets were also found in Canada, France, the
United Kingdom, and other countries of the European
Union. A study of the relationship between energy
density and the cost of freely chosen diets in a French
community11showed that dietary energy density was
diets were associated with a higher consumption of
grains, fats, and sweets; there was a negative association
between energy-dense diets and consumption of fruits
and vegetables.12,13In addition, the energy density of the
diet was inversely linked to the energy cost.
Replacing fats and sweets with more vegetables and
fruits was associated with higher diet costs: each 100 g
increment in additional fruit and vegetable consumption
increased diet costs.14,15In contrast, higher consumption
of fats and sweets was associated with a net savings in diet
costs. These data showed that sweets and fats cost less,
while low-energy-density diets high in vegetables and
are generally associated with higher energy intakes.
OBESITY: AN ECONOMIC HYPOTHESIS
abnormalities in biology,physiology,and behavior.16The
biological explanation has been that the observed crav-
ings for fats and sweets are driven by central metabolic
events,a serotonin or dopamine imbalance,altered leptin
levels, or the endogenous opiate peptide system. Physi-
ological explanations have invoked the glycemic index of
foods, individual differences in fructose metabolism,
satiety deficits, or insulin resistance. Psychological expla-
nations have addressed an addictive personality, a
cortisol-mediated response to stress, or simply the
seeking of comfort in high-fat foods. Environmental
approaches have blamed the susceptibility of individuals
to external cues provided by fast foods or snacks and the
inability to regulate calories following the consumption
of soft drinks.
Fewer studies have made the link between the low
cost of energy-dense foods and the obesity epidemic.The
present hypothesis is that the links seen between poverty
and obesity are primarily attributable to economic vari-
ables.15Unhealthy diets cost less,while the recommended
healthier diets cost more. As consumers reduce food
expenditures,their diet becomes increasingly energy rich
but nutrient poor.Whereas increasing food expenditures
below a certain limit virtually guarantees that the result-
ing diet will be nutrient poor and energy dense. House-
holds on a limited budget will find it difficult to eat more
healthfully unless they adopt unfamiliar eating habits,
depart from social norms, or eat mostly unpalatable
foods. Public policies to promote dietary change should
take into account food preferences and usual eating
The growing price gap between healthy and
unhealthy foods also supports the causal link between
poverty and obesity. The foods that have been found to
maintain their price are fats and sweets, which could
accentuate disparities in the access that people with lower
incomes have to healthy diets.
Given economic constraints, especially among lower-
income groups, not all consumers have the same degree
of choice when it comes to purchasing healthful fresh
produce, fruit, lean meats, and fish. For many, the choice
was removed long ago by economic and employment
policies. There are sound economic reasons why poverty
and obesity are so closely linked, and this could affect
future obesity-prevention strategies. A combination of
agricultural subsidies, pricing policies, regulatory action,
and consumer education, involving cooperation among
governments, academia, and the food industry, could
facilitate access to an affordable supply of fresh,nutrient-
rich foods. In addition, while the onus to provide low-
income consumers with inexpensive, healthy foods is
currently on the food industry,this view could shift to the
need for policies to address broader societal issues, such
as the falling value of the minimum wage and declining
neighborhood resources. Environmental and policy
interventions will be needed to address the observed
inequalities in access to healthy foods,particularly as they
relate to body weight and health.
Declaration of interest. The author has no relevant inter-
ests to declare.
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