Agriculture Reference
In-Depth Information
Overweight in children has also increased dramatically in the last several years.
In the United States, the prevalence of overweight among children 6 to 11 years old
has doubled, and the number of overweight adolescents has trebled since the 1960s
(Flegal and Trioano 2000, Ogden et al. 2002). Obesity is the most common health
problem faced by American children, with African American and Hispanic children
and children in low-income households the most severely affected. However, child-
hood obesity is a global phenomenon and increasingly extends into the develop-
ing world; for example, in Thailand the prevalence of obesity in 5- to 12-year-olds
rose from 12.2 to 15.6% in just 2 years (World Health Organization 2003). Similar
statistics have been documented in many other low- and middle-income countries.
Rising rates of obesity in children are particularly problematic, not only because
overweight children have a high risk of growing into obese adults, but also because
obesity-associated illnesses, including diabetes and high blood pressure, accompany
obesity even at young ages.
While the prevalence of obesity has increased across all population segments
in the United States, rates are highest among women, middle-aged adults, and
those with less education and income. Interestingly, in the United States the asso-
ciation of higher socioeconomic status with lower rates of obesity in women is
less marked among Hispanics and African Americans than among non-Hispanic
whites (Friel et al. 2007). In developing countries, the long-standing pattern has
been that higher socioeconomic status is associated with higher rates of obesity,
but that pattern is changing. In Brazil, for example, the obesity/socioeconomic
status relationship has already reversed for women, with poorer women now at
higher risk than richer ones (Monteiro et al. 2004b). Assuming that this trend will
repeat itself in other large populations, the obesity epidemic threatens to widen
already existing health disparities in a number of populations (Monteiro et al.
2004a). In other words, the burden will increasingly fall on the poor, as does the
burden of undernutrition.
the ReAl cAuses of the obesIty ePIdemIc
While body weight has a high degree of heritability and genetics contributes 25-40%
to individual variation in weight, the rapidity with which obesity has emerged
as a highly prevalent condition argues that profound changes in the environment
are responsible for the current global trend. These include urbanization and eco-
nomic development with attendant decreases in demands for physical activity, as
well as globalization of food commodities and trade resulting in widespread dietary
change. These quite powerful environmental changes have occurred superimposed
on unprecedented changes in the age structure of many of the world's populations.
The term
nutrition transition
is being used to describe the shift toward obesity and
nutrition-related chronic disease dominating the public health landscape in develop-
ing countries (Popkin 1998). To understand it, it is necessary to appreciate the demo-
graphic and epidemiologic transitions that underlie it.
