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Overweight and Obesity: An Overview
Is there a quick answer to the question, "what contributes to
overweight and obesity?"
Overall
there are a variety of factors that play a role in obesity. This
makes it a complex health issue to address. This section will
address how behavior, environment, and genetic factors may have an
effect in causing people to be overweight and obese.
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Overweight and obesity
result from an energy imbalance. This involves eating too
many calories and not getting enough physical activity.
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Body weight is the result of
genes, metabolism, behavior, environment, culture, and
socioeconomic status.
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Behavior and environment
play a large role causing people to be overweight and obese.
These are the greatest areas for prevention and treatment
actions.
Adapted from
U.S. Surgeon General’s Call to Action to Prevent and Decrease
Overweight and Obesity, 2001 |
The Caloric Balance Equation
When it
comes to maintaining a healthy weight for a lifetime, the bottom
line is — calories count! Weight management is all about
balance—balancing the number of calories you consume with the number
of calories your body uses or "burns off." |
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A
calorie is defined as
a unit of energy supplied by food. A calorie is a calorie
regardless of its source. Whether you’re eating carbohydrates,
fats, sugars, or proteins, all of them contain calories.
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Caloric
balance
is like a scale. To remain in balance and maintain your body
weight, the calories consumed (from foods) must be balanced by the
calories used (in normal body functions, daily activities, and
exercise).
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If you are… |
Your caloric balance status is …. |
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Maintaining your weight |
"in balance."
You are eating roughly the same number of calories that your
body is using. Your weight will remain
stable.
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Gaining weight |
"in caloric
excess." You are eating more calories than your body is using.
You will store these extra calories as fat and you’ll
gain weight.
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Losing weight |
"in caloric
deficit." You are eating fewer calories than you are using.
Your body is pulling from its fat storage cells for energy, so
your weight is decreasing. |
Genetics and
the environment may increase the risk of personal weight gain.
However, the choices a person makes in eating and physical activity
also contributes to overweight and obesity.
Environment
People may
make decisions based on their environment or community. For example,
a person may choose not to walk to the store or to work because of a
lack of sidewalks. Communities, homes, and workplaces can all
influence people's health decisions. Because of this influence, it
is important to create environments in these locations that make it
easier to engage in physical activity and to eat a healthy diet.
The Surgeon General’s Call to
Action to Prevent and Decrease Overweight and Obesity 2001
identified action steps for several locations that may help prevent
and decrease obesity and overweight. The following table provides
some examples of these steps.
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Location |
Steps to Help Prevent and Decrease Overweight and Obesity |
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Home |
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Reduce time spent watching
television and in other sedentary behaviors
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Build physical activity into
regular routines
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Schools |
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Ensure that the school
breakfast and lunch programs meet nutrition standards
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Provide food options that
are low in fat, calories, and added sugars
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Provide all children, from
prekindergarten through grade 12, with quality daily
physical education
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Work |
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Create more opportunities
for physical activity at work sites
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Community |
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Promote healthier choices
including at least 5 servings of fruits and vegetables a
day, and reasonable portion sizes
Encourage the food industry to provide reasonable food and
beverage portion sizes
Encourage food outlets to increase the availability of
low-calorie, nutritious food items
Create opportunities for physical activity in communities
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Genetics
How do genes affect obesity?
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"Despite
obesity having strong genetic determinants, the genetic
composition of the population does not change rapidly.
Therefore, the large increase in . . . [obesity] must
reflect major changes in non-genetic factors."
Hill, James
O., and Trowbridge, Frederick L. Childhood obesity: future
directions and research priorities.
Pediatrics.
1998; Supplement: 571. |
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Science
shows that genetics plays a role in obesity. Genes can directly
cause obesity in disorders such as Bardet-Biedl syndrome and
Prader-Willi syndrome.
However genes do not always predict future health. Genes and
behavior may both be needed for a person to be overweight. In some
cases multiple genes may increase one’s susceptibility for obesity
and require outside factors; such as abundant food supply or little
physical activity.
Other Factors
Diseases and Drugs
Some illnesses may lead to obesity or weight gain. These may include
Cushing's disease, and polycystic ovary syndrome. Drugs such as
steroids and some antidepressants may also cause weight gain.
A doctor is the best source to tell you whether illnesses,
medications, or psychological factors are contributing to weight
gain or making weight loss hard.
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