and Posner, and Lakdawalla and Philipson.
They all concluded that increases in body-mass
index (BMI) over time are related to a lower
use of calories (due to reductions in the strenuousness
of work). Philipson and Posner presented
a theoretical model that suggests that
technological change is a major factor that contributes
to rising obesity rates. Philipson also
suggested other potential reasons that could
explain the growth of obesity rates. These reasons
include, among others, the change from
rural to urban societies and changes in cultural
habits, such as a higher rate of passive entertainment.
Lakdawalla and Philipson used data
from the National Health Interview Survey
from 1976 to 1994, and from the National Longitudinal
Survey ofYouth from the period 1982
through 1998. They empirically estimated the
relationship between obesity and reduction of
physical activity and concluded that about40%
of the total growth in obesity is due to expansion
of the food supply, potentially through
agricultural innovation, and about 60% is due
to demand factors such as decline in physical
activity in market and home production.
Chou, Grossman, and Saffer looked at the
role played by other societal forces that may
alter the individual’s time allocation for food
preparation and consumption in an industrialized
society. In particular, their main hypothesis
was that given the higher value of time in
industrialized societies, individuals would devote
more time to the labor market, thereby
having less time available for food preparation
and leisure. Using cross-sectional data from
the Behavioral Risk Factor Surveillance System
(BRFSS), they analyzed, among other factors,
the expansion of the different restaurants,
the price of a meal in each type of restaurant,
the price of food consumed at home, the
price of cigarettes, hours of work per week, and
hourly wage rates by sociodemographic characteristics.
Their main results indicated a large
positive effect associated with the per capita
number of restaurants. In addition, the authors
found that downward trends in food prices account
for part of the upward trend in weightrelated
incidence, while increases in cigarette
prices are associated with growth in weightrelated
problems.
The studies discussed above provide explanations
for the growth of obesity mainly in
the United States. To our knowledge, only the
work by Cutler, Glaeser, and Shapiro has attempted
to study the factors affecting overweight
and obesity rates in multiple countries