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Until recently, obesity was defined as weighing 130% of ideal or desirable weight. Now, the body
mass index (BMI) (weight in kilograms divided by the square of height in meters) is used. A person
with a BMI between 25 and 30 is considered overweight, and one with a BMI over 30 is considered
obese.41
As a major health problem that recently has reached epidemic proportions in the United States,
Europe and other countries, obesity accounts for substantial morbidity and mortality and has a
profound negative impact on health-related quality of life. The health implications of obesity are
so serious that obesity has been designated a major cause of death in the United States.41
Etiology
Epidemiology
Major Approaches to Treatment
Etiology
The simple cause of obesity is that fewer calories are used than are taken in; however, the
underlying causes are more complex. A variety of social, behavioral, cultural, environmental,
physiological and genetic factors contribute to this condition. For many overweight and obese
individuals, substantial changes in behavior may be necessary to develop a healthier lifestyle.4
Genetic determinants
Genes have recently been found to play a significant role in the regulation of body weight. Studies
of twins raised apart have estimated that the heritability of BMI is about 80%. Adoption and family
studies indicate a more reasonable 33% heritability.4
Environmental determinants thus reasonably account for the other 66% of influences on weight
regulation. Among these are:4
- Socioeconomic status
A negative relationship, especially among women, affecting both energy intake and energy expenditure,
has been found between socioeconomic status and obesity.
- Large food intake
Using the doubly labeled water method (stable isotopes of hydrogen and oxygen) indicates that
obese individuals have a high level of energy expenditure, requiring a large food intake that
includes large fat intake. Fat intake has been independently associated with obesity.
- Sedentary lifestyle
Although food intake increases with a high level of energy expenditure, food intake does not appear
to decrease with a low level of energy expenditure.
Regulatory determinants
These include pregnancy, increases in fat cells and adipose tissue mass during infancy and
childhood, brain damage, certain drugs, endocrine factors and psychological factors.
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Epidemiology
Prevalence of Obesity (1998)38
17.9% of all American adults
17.7% of males
18.1% of females
16.6% of Caucasians
26.6% of African Americans
20.8% of Hispanics
11.9% of other
- Obesity increases with age, with decreases beginning after age 60.38
- Education is inversely related to obesity, except for magnitude of increase in obesity.38
- Former smokers are more likely to be obese than are those who never smoked or those who currently smoke. 38
Prevalence of Comorbidities (1988-1994) 39
Class 1 = BMI of 30-34.9
Class 2 = BMI of 35-39.9
Class 3 = BMI of 40 and above
| Type 2 diabetes mellitus (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
10.10 |
12.30 |
10.65 |
2.03 |
| Females |
7.24 |
13.16 |
19.89 |
2.38 |
| Gallbladder disease (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
5.38 |
5.80 |
10.17 |
1.93 |
| Females |
15.99 |
19.15 |
23.45 |
6.29 |
| Coronary heart disease (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
16.01 |
10.21 |
13.97 |
8.84 |
| Females |
12.56 |
12.31 |
19.22 |
6.87 |
| Hyperlipidemia (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
39.17 |
34.01 |
35.63 |
26.89 |
| Females |
40.37 |
40.96 |
36.39 |
26.89 |
| High blood pressure (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
48.95 |
65.48 |
64.53 |
23.47 |
| Females |
47.95 |
54.51 |
63.16 |
23.26 |
| Osteoarthritis (%), by obesity class and gender |
| Gender |
Class 1 |
Class 2 |
Class 3 |
Normal |
| Males |
4.66 |
5.46 |
10.04 |
2.59 |
| Females |
9.94 |
10.39 |
17.19 |
5.22 |
Mortality1
Between 280,000 and 325,000 deaths in 1991 were attributable to obesity.
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Major Approaches to Treatment
Treatment programs for overweight and obesity can be do-it-yourself, nonclinical or clinical.4
Do-It-Yourself Programs
These programs include self-help groups, such as Overeaters Anonymous or Take Off Pounds Sensibly
(TOPS); books and articles; community or work-site programs; and weight-loss products, such as
meal-replacing drinks.4
Nonclinical Programs
Nonclinical programs are generally run by a corporate entity, but also include some form of
counseling and instruction/guidance materials prepared by health care professionals. An example
is Weight Watchers®. Although the efficacy of these programs is hard to determine since they publish
little outcomes data, they are popular and readily available, and may be useful in concert with
physician direction about sensible diets and exercise programs.4
Clinical Programs
These programs are provided by licensed health care professionals. They may be part of a commercial
endeavor or be offered through a medical practice. 4 Clinical programs often provide a combination
of diet and nutrition counseling, behavior therapy, and exercise found to be important in successful
weight loss.41
Diet and Nutrition Counseling
These programs assist in tailoring diets for both weight loss and maintenance of weight loss, resulting
in steady but small losses that can be maintained. Very low-calorie diets are no longer as popular
as they once were.4 Nutrition education is a key part of these programs. The proportion of calories
from fat, protein and carbohydrate sources; salt, mineral and vitamin content; and the amount of
dietary fiber in the food consumed all play a critical role in preventing disease. The Dietary
Guidelines for Americans recommend a diet consisting of a variety of foods, including grain products,
vegetables and fruits, that are moderate in salt, sodium, and sugars and low in fat, saturated fat,
and cholesterol.
Behavior Therapy
These programs try to change long-held habits and beliefs. No single method or combination of
methods has been shown to be superior, however.41
Ethical Drugs
Medication is a valuable adjunct to diet plans and behavior therapy. 41 XENICAL has been found to
be effective when combined with a diet having no more than 30% of calories from fat.
In clinical trials involving 1064 patients, 69% on XENICAL plus diet lost 3% or more of initial body
weight within 3 months, with a mean loss of 13 lbs.18
In clinical trials, the overall mean weight loss from randomization to the end of 1 year in the
intent-to-treat population was 13.4 lbs in patients treated with XENICAL plus diet versus 5.8 lbs
in placebo-treated patients.
Surgery
Surgical treatment should be considered only for those with severe obesity (i.e., a BMI greater
than 40) and one or more comorbid diseases who have also been shown to be intractable to medical
treatment.13 The NIH has defined vertical banded gastroplasty and Reux-en-Y gastric bypass as safe
and effective surgical procedures.13 Decline in excess body weight of between 40% and 70% results.
More than three-quarters of patients become independent of antihypertensives and antihyperglycemic
medications after surgery.13
XENICAL: Part of a Comprehensive Weight-Loss Strategy
As physicians become increasingly aware of the health benefits of even modest weight loss (5% to 10%),
they will need to communicate this understanding to their overweight patients. Through frequent
contact and reinforcement of appropriate behavior,26 physicians can have a major impact on their
patients' ability to attain the clinically significant benefits associated with weight loss.41
Even with good support programs, however, over time patients usually regain lost weight. Although diet
and exercise are effective means for losing weight, patients are poorly compliant over the long
term.10 Adding drug therapy to a regimen of caloric restriction, however, may facilitate weight
loss and thus may also help prevent the weight regain associated with caloric restriction alone.41
Patients using XENICAL, in addition to diet and exercise, learn the skills needed to maintain a
healthy lifestyle even after they reach their weight-loss goals.
Information on Healthy People 2010 objectives, nutrition and overweight treatment guidelines is
available on our page of useful Web sites.
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Managing Patients with Obesity-Related Comorbidities
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