| |
Overweight and
Obesity Facts
One in three or 58 million American adults
aged 20 through 74 are overweight. According to data from the Third National
Health and Nutrition Examination Survey (NHANES III), the number of overweight
Americans increased from 25 to 33 percent between 1980 and 1991. The survey also
shows that minority populations, specifically minority women, are
disproportionately affected: approximately fifty percent of African American and
Mexican American women are overweight. By a similar definition, more than one in
five children and adolescents aged 6 through 17 are also overweight. Even using
a more rigorous definition recommended for youths, 11 percent of children and
adolescents are overweight, up from approximately 5 percent in the 1960s and
70s. Overweight and obesity is a known risk factor for diabetes, heart disease,
high blood pressure, gallbladder disease, arthritis, breathing problems, and
some forms of cancer.
Overweight is the excess amount of body
weight that includes muscle, bone, fat, and water. Obesity is the excess
accumulation of body fat. One can be overweight without being obese: a body
builder who has a lot of muscle, for example. However, for practical purposes,
most people who are overweight are also obese.
Doctors and scientists generally agree that
men with more than 25 percent body fat and women with more than 30 percent
body fat are obese. However, it is difficult to measure body fat precisely.
The most accepted method has been to weigh a person underwater. But underwater
weighing is a procedure limited to laboratories with special equipment.
Two simpler methods for measuring body
fat are skinfold thickness measurements and bioelectrical impedance analysis (BIA).
Skinfold thicknesses are measures of the thickness of skin and subcutaneous
(lying under the skin) fat at targeted sites of a person's body such as the
triceps (the back of the upper arm). Measurements of skinfold thickness depend
on the skill of the examiner, and may vary widely when measured by different
examiners.
BIA sends a harmless amount of an
electrical current through the body, which estimates total body water.
Generally, a higher percent body water indicates a larger amount of muscle and
lean tissue. Mathematical equations can translate the percent body water
measure into an indirect estimate of body fat and lean body mass. BIA may not
be accurate in severely obese individuals, and is not useful for tracking
short-term changes in body fat brought about by diet or exercise.
In addition to skinfold thickness
measures and BIA, doctors also use weight-for-height tables and body mass
index measures (BMI) to determine if a person is at a desirable body weight.
Doctors and obesity researchers prefer BMI to other measurements. Body mass
index is found by dividing a person's weight in kilograms by height in meters
squared. When a man's BMI is over 27.8, or woman's exceeds 27.3, that person
is considered overweight. The degree of obesity associated with a particular
BMI ranges from mild obesity at a BMI near 27, moderate obesity at 30, severe
obesity at 35, to very severe obesity at 40 or greater.1
An estimated 41 percent of the population has a BMI greater than 25.1
Like weight-for-height tables, BMI does not measure body fat. While limited,
these measures nevertheless help doctors, patients, and the public assess a
person's desirable body weight.
- Total number of overweight adults:
(20 through 74 years old) approximately one-third or 58 million Americans.2
(numbers derived from NHANES III, 1988-91, which defines overweight as a
BMI value of 27.3 percent or more for women and 27.8 percent or more for
men)
- Overweight adult females (20-74
years old): 32 million (1990)2
- Overweight adult males (20-74
years old): 26 million (1990)2
- Total number of overweight youths:
6 through 17 years old approximately 11 percent or 4.7 million children in
this age group.3 (numbers derived from NHES II
and III, which defines overweight by the 95th percentile of BMI)
- The percentage of dietary fat
American adults eat.
34 percent 4
- The percentage of saturated fat
American adults eat.
12 percent 4
- The number of extra calories a person
must eat to gain a pound or burn to lose a pound.
3,500 calories 5
- The percentage of adult American
women trying to lose weight at any given time.
33 to 40 percent 6
- The percentage of adult American men
trying to lose weight at any given time.
20 to 24 percent 6
- The average number of calories a
person burns eating.
.023 kcal per minute/per kilogram of body weight 7
- The annual number of deaths
attributable to poor diet and inactivity.
300,000 deaths 8
Noninsulin-dependent diabetes mellitus (NIDDM)
Nearly 80 percent of patients with NIDDM
are obese.9 Much of the estimated $11.3 billion
dollars spent each year to diagnose, treat, and manage NIDDM, including
treatment for diabetic ketoacidosis, diabetic coma, diabetic eye disease,
and diabetic kidney disease, stems from obesity. 9
Gallbladder disease
The incidence of symptomatic gallstones
soars as a person's body mass index (BMI) goes beyond 29.10
Nearly $2.4 billion dollars or 30 percent of the total amount spent annually
on gallbladder disease and gallbladder surgery are related to obesity.10
Heart disease
Nearly 70 percent of the diagnosed cases
of cardiovascular disease are related to obesity.
Obesity
Obesity accounts for $22.2 billion, or 19
percent, of the total cost of heart disease. 10
High blood pressure
Obesity more than doubles one's chances
of developing high blood pressure, which affects approximately 26 percent of
obese American men and women. The annual cost of obesity-related high blood
pressure is close to $1.5 billion dollars.10
Breast and colon cancer
Almost half of breast cancer cases are
diagnosed among obese women; an estimated 42 percent of colon cancer cases
are diagnosed among obese individuals. Obesity-related breast cancer and
colon cancer account for 2.5 percent of the total costs of cancer, or $1.9
billion dollars, annually.10
Indirect costs:
Americans spend an additional $33 billion
dollars annually on weight-reduction products and services, including diet
foods, products, and programs. 10
Weighing the Options: Criteria
for Evaluating Weight-Management Programs. Institute of Medicine, National
Academy of Sciences. 1995; 50-51.
Kuczmarski, R.J., Johnson, C.L.,
Flegal, K.M., Campbell, S.M. Increasing prevalence of overweight among US
adults. Journal of the American Medical Association. 1994; 272:205-211.
Troiano, R.P., Kuczmarski, R.J.,
Johnson, C.L., Flegal, K.M., Campbell, S.M. Overweight prevalence and trends
for children and adolescents: The National Health and Nutrition Examination
Surveys, 1963 to 1991. Archives of Pediatrics and Adolescent Medicine,1995;
149:1085-1091.
Daily dietary fat and total
food-energy intakes: Third National Health and Nutrition Examination Survey,
Phase I, 1988-1991. MMWR Morbidity and Mortality Weekly Report. 1994;
43:116-117, 123-125.
Weight control: What works and why.
Medical Essay. Mayo Foundation for Medical Education and Research,
1994.
Methods of Voluntary Weight Loss
and Control. National Institutes of Health Technology Assessment
Conference Statement, March 30-April 1, 1992. Copies are available from the
Office of Medical Applications Research, National Institutes of Health,
Federal Building, Room 618, Bethesda, MD 20892.
McArdle, W.D., Katch, F.I. &
Katch, V.L. Exercise Physiology: Energy, Nutrition & Human Performance.
Philadelphia, Pa: Lea & Febiger; 1991.
McGinnis, J.M. & Foege, W.H.
Actual causes of death in the United States. Journal of the American
Medical Association. 1993; 270:2207-2212.
Diabetes in America, 2nd
Edition, The National Institutes of Diabetes and Digestive and Kidney
Diseases, 1995, NIH publication number 95-1468.
Colditz, G.A. Economic costs of
obesity. American Journal of Clinical Nutrition, 1992; 55:503-507s.
Weight-control Information
Network
1 Win Way
Bethesda, MD 20892-3665
Phone: (301) 984-7378 or 1-800-WIN-8098
Fax: (301) 984-7196
E-mail: win@info.niddk.nih.gov
The Weight-control Information Network
(WIN) is a service of the National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK).
Path:
Home>Education>Food
and Nutrition Information>Overweight
and Obesity Facts
|
|
