By any measure, more Americans are heavier today than ever before.
Nearly 2 out of 3 adults now meet or exceed the clinical definition
of overweight, and 3 out of 10 children are overweight or at risk
for overweight. Especially alarming to public health experts is
the rapid weight gain witnessed since the mid-1970s. Since then,
obesity has doubled among adults and tripled among adolescent boys
and girls.
People gain weight when energy consumption (or calories) from food
consistently exceeds energy expended on bodily functions and physical
activity. Therefore, the current obesity epidemic must be due to
some combination of people eating more and moving less. “Environmental” changes
in recent decades that have been linked to obesity include more
fast foods, bigger portion sizes, and more sedentary lifestyles.
Still, why are more people making the choices that lead to weight
gain
and obesity?
Economists are attempting to answer
this by examining the incentives and disincentives people face
when making food
and physical activity
choices. In earlier agricultural and industrial times, work was
strenuous and people, in effect, were paid to exercise (that is,
undertake work). Today, physical labor has become more rare and
people pay to undertake—and budget time for—exercise.
Inexpensive alternative uses for leisure time, such as TV or video
games, only compound the problem.
Technological progress has also altered
incentives for the type and amount of food people eat. A more
efficient
agricultural system
has cut food prices, especially of calorie-dense foods. Advances
in food processing and packaging have introduced a multitude of
ready-to-eat foods, available virtually anywhere and at any time.
This has reduced the time “cost” of food preparation
and consumption. People have responded to these incentives by increasing
the quantity and variety of foods they consume.
At the same time, technology-driven progress in medical and epidemiological
research warns us of the serious health consequences of obesity.
These warnings should act as a disincentive against choices that
lead to excess body weight, but apparently have not. By studying
how people evaluate long-term health consequences when making short-term
food and activity choices, economists hope to better understand
the causes behind the increase in obesity.
Download PDF version