WHICH IS MORE
IMPORTANT: NATURE OR NURTURE?
Causes of Obesity
In scientific terms, obesity occurs when a
person's calorie intake exceeds the amount of energy he or she burns. What causes this imbalance
between consuming and burning calories is unclear. Evidence suggests that obesity often has more
than one cause. Genetic, environmental, psychological, and other factors all may play a part.
Obesity tends to run in families, suggesting
that it may have a genetic cause. However, family members share not only genes but also diet and
lifestyle habits that may contribute to obesity. Separating these lifestyle factors from genetic
ones is often difficult. Still, growing evidence points to heredity as a strong determining factor
of obesity. In one study of adults who were adopted as children, researchers found that the
subjects' adult weights were closer to their biological parents' weights than their adoptive
parents'. The environment provided by the adoptive family apparently had less influence on the
development of obesity than the person's genetic makeup.
Nevertheless, people who feel that their genes have
doomed them to a lifetime of obesity should take heart. Many people genetically predisposed to
obesity do not become obese or manage to lose weight and keep it off.
People can't change their genetic makeup, of course,
but they can change what they eat and how active they are. Some people have been able to lose weight
and keep it off by:
Although genes are an important factor in
many cases of obesity, a person's environment also plays a significant part. Environment includes
lifestyle behaviors such as what a person eats and how active he or she is. Americans tend to have
high-fat diets, often putting taste and convenience ahead of nutritional content when choosing
meals. Most Americans also don't get enough exercise.
Learning how to choose more nutritious
meals that are lower in fat. ( See
Learning to recognize environmental cues
(such as enticing smells) that may make them want to eat when they are not
Becoming more physically active.
Psychological factors also may influence
eating habits. Many people eat in response to negative emotions such as boredom, sadness, or anger.
While most overweight people have no more
psychological disturbance than normal weight people, about 30 percent of the people who seek
treatment for serious weight problems have difficulties with binge eating. During a binge eating
episode, people eat large amounts of food while feeling they can't control how much they are eating.
Those with the most severe binge eating problems are
considered to have binge eating disorder. These people may have more difficulty losing weight and
keeping the weight off than people without binge eating problems. Some will need special help, such
as counseling or medication, to control their binge eating before they can successfully manage their
other causes of obesity
Some rare illnesses can cause obesity. These
include hypothyroidism, Cushing's syndrome, depression
and certain neurologic problems that can lead to overeating. Certain drugs, such as steroids and
some antidepressants, may cause excessive weight gain. A doctor can determine if a patient has any
of these conditions, which are believed to be responsible for only about one percent of all cases of