TABLE 1
Causes
Obesity is caused by a variety of factors, all of
which result in an excess of caloric intake relative to
the body’s expenditure of energy (calories) at rest,
during activity, and, in childhood and adolescence,
for growth. Calorie intake in excess of these needs is
converted to fat. Less than 2 percent of obesity in
childhood is due to endocrinologic conditions, such
as thyroid disease. An equally small percentage is due
to genetic disorders (e.g., the Prader-Willi Syn-
drome). Though obesity ‘‘runs in families,’’ the genet-
ic contributions to fatness are not well understood. A
shared environment also contributes to the heredi-
tary pattern of obesity, with parental influences on
diet and exercise during childhood and adolescence.
Numerous studies have failed to precisely define the
relative contributions of caloric intake and expendi-
ture to the development of obesity. The difference in
daily intake necessary to result in as much as a ten-
pound difference in weight gain over the course of a
year is actually as little as a hundred calories per day.
Studies have shown that more time spent using televi-
sion, VCRs, and video games is associated with a
greater likelihood of obesity and that decreasing the
amount of time spent watching television correlates
with less weight gain.
Some interesting developmental factors may con-
tribute to overconsumption of calories. These include
difficult infant or child temperament, poor self-
regulation of intake, and an ‘‘obese eating style,’’ in-
volving rapid eating and rapid consumption of calo-
ries. Studies of infant feeding have revealed a style of
vigorous feeding, similar to the obese eating style,
with rapid sucking, at higher pressure, resulting in
greater caloric intake at a feed. Studies of children’s
ability to self-regulate dietary intake have found
poorer self-regulation of eating in fatter girls and in
children exposed to a highly controlling parenting
style. Studies of child temperament have found that
difficult children (low in rhythmicity, approach, and
adaptability; high in intensity; and negative in mood)
show more rapid weight gain, perhaps as a result of
being overfed by parents who use feeding as a sooth-
ing technique, and may later use eating as a technique
for comforting themselves.Consequences
Obesity has significant medical consequences, es-
pecially for adults, but also for children and adoles-
cents. Among adults, obesity is a major risk factor for
heart disease, myocardial infarction (heart attack),
strokes, cancer, and many other diseases. During ado-
lescence and childhood, obesity can contribute to
problems of the joints, especially the hips, knees, and
spine, and more difficulty with chronic illnesses, such
as asthma. Obesity affects the endocrine system, lead-
ing to changes in sex hormones, adrenal hormones,
and the ability to respond appropriately to insulin.
Type II diabetes has become more common during
adolescence as the prevalence of obesity has in-
creased. Sleep apnea, due to obstructed breathing
during sleep, is more common among obese children
and adolescents.
The psychological consequences of obesity are
very important during childhood and adolescence.
Though some studies have found similar prevalence
of psychological problems in obese and normal
weight children, obese children are often teased by
other children, excluded from peer group activities,
picked last (if at all) for sports teams, and shunned
during social activities. Stigmatization of obesity is
commonplace throughout the media, especially
television, movies, and popular magazines. Unfortu-
nately, poor self-esteem, depression, and the devel-
opment of eating disorders occur often in individuals
with histories of obesity. Obese adults are even dis-
criminated against when they apply for jobs and dur-
ing the application process for college.Treatment
Obesity is not a disease that can be diagnosed on
the basis of one or more blood tests or treated with
one or a combination of medications. Until the true288 OBESITY