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Overweight, Obesity and Weight Management
Backgrounder
Rates of overweight and obesity in the United States have
grown to epidemic proportions over the last 20 years. In 2005, the Surgeon
General estimated that two-thirds of Americans were overweight or obese. The
latest data from the NCHS show that 30 percent of U.S. adults 20 years of age
and older - more than 60 million people - are obese. The direct costs and indirect
costs of overweight and obesity amounted to about $117 billion in 2000.
Intangible costs (such as impaired quality of life) have not been estimated, but
given the social and psychological consequences of obesity, they are likely to
be enormous.
Childhood overweight and obesity rates are especially alarming. According to
the National Center for Health Statistics (NCHS) report, Health, United States,
2005, 16 percent of children and adolescents aged six to 19 were overweight. The
prevalence of overweight among children and adolescents has doubled and tripled,
respectively, over a period of twenty-six years (1976-2002). Research shows that
overweight children are more likely to become overweight adults and, therefore,
are at greater risk for associated health problems. In fact, 60 percent of
overweight five- to 10-year-old children already have at least one risk factor
for heart disease.
While all children and adolescents are at risk, those belonging to certain
ethnic population groups may be more predisposed to overweight than others. Data
from the National Health and Nutrition Examination Survey (NHANES 2003-2004)
indicated that the risk of overweight among Mexican-American children and
adolescents aged two to 19 is 41 percent: more than five and 10 percentage
points higher than their non-Hispanic white (35 percent) and non-Hispanic black
(30 percent) contemporaries, respectively.
Global in Scope
Overweight and obesity are not just a U.S. issue; its prevalence is
increasing throughout the world's population. The World Health Organization
(WHO) reports that more than one billion adults are overweight and at least 300
million of them are clinically obese. Levels of obesity range from below five
percent in China, Japan, and certain African nations to over 75 percent in urban
Samoa.
Worldwide, over 22 million children under the age of five are overweight as
are 155 million school-age children. In a 2006 review published in the
International Journal of Pediatric Obesity, North America, Europe, and parts
of the Western Pacific have the highest prevalence of overweight among children
(approximately 20 to 30 percent). Furthermore, the levels of obesity among
school-age children in countries undergoing economic growth, such as Brazil,
Chile, Mexico, and Egypt, are catching up with fully industrialized countries.
Based on the current secular trends and the International Obesity Task Force
(IOTF) criteria, experts estimate that one in seven children in the Americas
will be obese by 2010 as will one in every 10 children in the Eastern
Mediterranean and European regions.
WHO considers obesity to be one of the top 10 causes of preventable death
worldwide. While malnutrition and unsafe sex account for more deaths, high blood
pressure, smoking, high cholesterol, and obesity are impacting both
industrialized and developing countries. The 2003 Joint FAO/WHO Expert
Consultation on Diet, Nutrition, and the Prevention of Chronic Diseases
estimated that non-communicable diseases (NCDs) such as obesity, diabetes,
hypertension, stroke, and various forms of cancer accounted for 60 percent of
the 55.7 million deaths that occurred in 2000. If unchecked, NCDs are expected
to contribute nearly 75 percent of all deaths by the year 2020.
Definitions and Measures of Overweight/Obesity
According to the National Institutes of Health (NIH), overweight refers to an
excess of body weight compared to set standards. The excess weight may come from
muscle, bone, fat, and/or bodily water. Obesity refers specifically to having an
abnormally high proportion of body fat. A person can be overweight without being
obese, as in the example of a bodybuilder or other athlete who has a lot of
muscle. However, many people who are overweight are also obese.
The Centers for Disease Control and Prevention (CDC), researchers, and health
professionals use Body Mass Index (BMI) as the preferred method for determining
overweight and obesity in adults, though other methods exist and are in use. BMI
is a calculation that divides a person's weight in kilograms by height in meters
squared (BMI = [kg/m2]). BMI can also be calculated in pounds and inches: BMI =
[lbs/in2] x 703. The general guideline currently recommended by the CDC is that
individuals with a BMI of 25 to 29.9 are considered overweight, and those
individuals with a BMI greater than 30 are considered obese. It is important to
note that BMI does not use body fat or frame size in its calculations.
Therefore, it is possible for an individual with a high proportion of lean body
mass (muscle) to have an elevated BMI and not necessarily be at risk for adverse
health conditions associated with overweight and obesity. These charts can be
found at the CDC Web site:
CDC Obesity.
For children, gender-specific BMI charts have been developed. Children with a
BMI at or above the 95th percentile represented in these charts are considered
overweight. Children in the 85th percentile are considered at risk for
overweight. These charts can also be found on the CDC Web site:
CDC BMI According to Age.
What are the Health Implications?
The consequences of overweight and obesity can range from psychological
effects that impact quality of life (e.g. poor self-esteem, discrimination,
depression) to physiological conditions that put an individual at risk for
premature death. These conditions include the following:
- Hypertension
- Dyslipidemia (high total cholesterol or high levels of
triglycerides)
- Type 2 diabetes
- Heart disease
- Stroke
- Gallbladder disease
- Osteoarthritis
- Sleep apnea and respiratory problems
- Some cancers (such as endometrial, breast, and colon)
In research, the term "metabolic syndrome" has been widely used to refer to
obesity, a combination of the above health factors - diabetes, hypertension,
dyslipidemia - and signs of kidney disease. It has been suggested that the
metabolic syndrome increases the risk for heart disease more than the individual
health factors alone. However, a joint statement issued by the American Diabetes
Association and the European Association for the Study of Diabetes asserts that
there is no evidence supporting this theory. In other words, metabolic syndrome
should not be treated as a unique cluster of diseases until the science behind
it is clear.
Most health professionals believe that the more overweight an individual is,
the higher the risk for developing health complications. Fortunately, the
converse also appears true. By losing even 10 percent of body weight, an
overweight individual can improve his or her health, providing the weight loss
is maintained.
How Did We Get Here?
Prior to World War II, concern focused on health conditions caused by
nutrient deficiency (e.g., hunger, rickets, beri beri). As the United States
became more prosperous, attention began to shift from nutritional deficiencies
to conditions associated with over-consumption (e.g., heart disease, elevated
cholesterol, type 2 diabetes). However, in the 1970s, food insecurity was still
the major focus in this country, behind the development of social and health
programs. In the 1980s and 1990s, the focus was on nutrition and its impact on
chronic disease; with specific attention to dietary fats. Only within the last
decade have overweight and obesity been identified as important public health
concerns.
Similar shifts toward over-consumption and sedentary lifestyles have occurred
globally as other countries become increasingly westernized. Advancements in
nutrition, hygiene, and the control of infectious disease are being replaced in
developing countries by new health threats such as obesity, cardiovascular
disease, and diabetes. As urbanization and incomes rise, traditional diets that
are rich in complex carbohydrates and fiber are gradually replaced by western
diets that are lower in these nutrients and high in calories. Thus, obesity
often coexists with chronic under-nutrition in the same population, creating a
double disease burden.
In the simplest of terms, weight gain occurs when calories consumed (from
food and beverages) exceed calories expended (through basal metabolism, thermal
effect of food, and physical activity). The rise in overweight and obesity can
be attributed to an imbalance between calories consumed and calories expended or
a shift away from healthful food and lifestyle choices. These have resulted from
gradual changes in a complex set of social and environmental factors.
Individuals have become less active in all areas of their lives. Work and free
time have become much more sedentary. Food habits - such as diet composition,
increased eating away from the home, and larger portion sizes - have also changed.
There has also been a societal shift in the way communities are designed and
built. Often, there is a lack of resources or foresight to design urban and
suburban environments that encourage active lifestyles, such as sidewalks and
walking paths. Areas that require more study are the impact of genetics and
psychological factors on the development of overweight and obesity.
Strategies for Healthful Lifestyles and Weight
Management
Eating Patterns and Physical Activity
The 2005 Dietary Guidelines for Americans provide sciencebased advice
on healthful eating and physical activity for people over the age of two.
MyPyramid - the new food guidance system released by United States Department of
Agriculture (USDA) in 2005 - illustrates what and how much to eat from the basic
food groups for health. It includes twelve food intake patterns that are
consistent with the Dietary Guidelines and tailored to individual calorie needs
based on age, gender, and physical activity level. More information can be found
on the My Pyramid Web site:
My Pyramid.
Only 49 percent of adults in the United States engage in regular physical
activity consistent with recommendations, according to the latest Behavioral
Risk Factor Surveillance System survey conducted by the CDC. Furthermore, many
individuals who begin exercise programs either do not participate in them
regularly or do not maintain them for the long-term. In addition, the
development of new technologies and labor saving devices, changes in how we
spend our leisure time, and transformations in community design all have
contributed to an increase in sedentary behaviors in workplaces, schools, and at
home. Physical activity does not have to be strenuous to maintain weight and
promote health. MyPyramid, the American College of Sports Medicine, the CDC, and
the Surgeon General recommend that individuals of all ages accumulate at least
30 minutes of moderate-intensity physical activity on most, preferably all, days
of the week. To prevent weight gain, 60 minutes a day may be needed, based on
the Dietary Guidelines and MyPyramid. Preliminary evidence shows that
accumulated activity, or activity in short bursts, can provide health benefits,
similar to sustained activity. Additional health benefits may be gained by
increasing time or intensity of the activity and by including strength training.
Short, intense bouts of activity can deliver similar benefits as longer, less
intense sessions.
Promotion of Healthful Eating Guidelines and Messages
According to the 2002 Joint FAO/WHO Expert Consultation on Diet,
Nutrition, and the Prevention of Chronic Diseases, mass media campaigns and
other communication strategies, such as the former "Food Guide Pyramid" and the
"5-A-Day for Better Health" campaign, can have significant impact on awareness,
attitudes, knowledge, and intention to change. But behavior change is usually
not influenced unless the message is highly specific and achievable.
This is consistent with the results of the IFIC Foundation's 2003 qualitative
research, exploring consumers' perceptions n health and weight management. In a
series of focus groups that tested six messaging concepts, a message that
consumers particularly liked was, "Take a small step each day toward a healthy
weight. Over time, small steps add up to big changes." In addition to being
achievable, it was realistic and meaningful enough for them to cite several
examples of "small steps" they can do to eat better and exercise more. Further
details of this study may be found on the IFIC Foundation Web site:
IFIC Research.
Treatment
Evidence-based reports - such as the 2000 National Institutes of Health (NIH)
Practical Guide for Identification, Evaluation, and Treatment of Overweight and
Obesity in Adults - summarize approaches to weight loss and maintenance. The
general goals for weight loss and weight management are the following:
- Reduce body weight;
- Maintain a lower body weight over the long term; and,
- Prevent further weight gain as a minimum goal.
Weight loss should be achieved at a safe and healthful rate of 1-2 pounds per
week based on a reduction of 500 to 1,000 calories per day. Six months is a
reasonable time period to achieve a 10 percent reduction in body weight.
Effective weight management requires multiple techniques and strategies
including diet, physical activity, behavior therapy, pharmacotherapy, and weight
loss surgery. Guidelines to selecting the appropriate treatments can be based on
the degree of obesity as measured by BMI and the presence of comorbidities.
Successful interventions for weight loss and maintenance may combine a
low-calorie diet, increased physical activity, and behavior therapy. The
addition of weight loss drugs may be useful in people who are not successful in
losing the recommended one pound per week after six months. For people with
clinically severe obesity (BMI >35 with comorbid conditions or a BMI >40) in
whom other methods of treatment have failed, weight loss (or bariatric)
surgery, is an option.
Bariatric surgery involves restricting the size of the stomach or bypassing a
portion of the intestines which cause weight loss by limiting the amount of food
a person can consume in one meal and decreasing the proportion of nutrients
absorbed from a meal, respectively. A substantial number of complications are
associated with the procedure, although most of these are minor. A recent review
by the Agency for Healthcare Research and Quality, suggested that more studies
are needed to confirm or refute the relative efficacy of bariatric surgery in
less severe cases of obesity.
Summary
Rates of overweight and obesity have reached epidemic proportions in the
United States and around the world. This epidemic creates increased health care
costs associated with a variety of weight-related conditions such as heart
disease, type 2 diabetes, hypertension, some cancers, and hundreds of thousands
of premature deaths each year. The increase in childhood overweight is
especially alarming because overweight children are more likely to become
overweight or obese adults.
While several options to achieving weight loss and maintenance are available,
prevention rather than treatment is the most desirable approach. Leading a
healthful lifestyle by being physically active and practicing healthful eating
habits can be enjoyed by people of all ages. A varied, moderate, and balanced
diet combined with regular physical activity contribute to optimum health and
well-being throughout one's life.
Source: Originally printed in the 2007-2009 IFIC Foundation Media Guide on Food
Safety and Nutrition
Adapted by Editorial Staff, December 2007
Last update, August 2008
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