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Mokdad AH, Serdula MK, Dietz WH, Bowman BA, Marks JS, Koplan JP. The Spread of the Obesity Epidemic in the United States, 1991-1998. JAMA. 1999;282(16):1519–1522. doi:10.1001/jama.282.16.1519
Context The increasing prevalence of obesity is a major public health concern,
since obesity is associated with several chronic diseases.
Objective To monitor trends in state-specific data and to examine changes in the
prevalence of obesity among adults.
Design Cross-sectional random-digit telephone survey (Behavioral Risk Factor
Surveillance System) of noninstitutionalized adults aged 18 years or older
conducted by the Centers for Disease Control and Prevention and state health
departments from 1991 to 1998.
Setting States that participated in the Behavioral Risk Factor Surveillance
Main Outcome Measures Body mass index calculated from self-reported weight and height.
Results The prevalence of obesity (defined as a body mass index ≥30 kg/m2) increased from 12.0% in 1991 to 17.9% in 1998. A steady increase
was observed in all states; in both sexes; across age groups, races, educational
levels; and occurred regardless of smoking status. The greatest magnitude
of increase was found in the following groups: 18- to 29-year-olds (7.1% to
12.1%), those with some college education (10.6% to 17.8%), and those of Hispanic
ethnicity (11.6% to 20.8%). The magnitude of the increased prevalence varied
by region (ranging from 31.9% for mid Atlantic to 67.2% for South Atlantic,
the area with the greatest increases) and by state (ranging from 11.3% for
Delaware to 101.8% for Georgia, the state with the greatest increases).
Conclusions Obesity continues to increase rapidly in the United States. To alter
this trend, strategies and programs for weight maintenance as well as weight
reduction must become a higher public health priority.
Although attempts to lose weight are common in the United States,1,2 the prevalence of obesity has increased
since the 1980s.3,4 Such increases
will tremendously affect public health since obesity is strongly associated
with several chronic diseases, such as cardiovascular diseases and diabetes.5,6 Recent estimates suggest that obesity-related
morbidity may account for 6.8% of US health care costs.7
Recently published trend data from the National Health and Nutrition
Examination Surveys (NHANES) show the percentage of obese persons has increased
from 14.5% in the years 1976-1980 to 22.5% in 1988-1994.3
To monitor obesity trends since 1994 and to present state-specific results,
we used data from a large population-based survey to examine changes in the
prevalence of obesity among adults in the United States from 1991 to 1998.
We analyzed data from all states that participated in the Behavioral
Risk Factor Surveillance System (BRFSS). The BRFSS, a cross-sectional telephone
survey of noninstitutionalized adults aged 18 years or older, is conducted
by the Centers for Disease Control and Prevention and state health departments.
The BRFSS questionnaire concerns personal behaviors that increase risk for
1 or more of the 10 leading causes of death in the United States.8
The BRFSS uses a multistage cluster design based on random digit dialing
methods to select a representative sample from each state's noninstitutionalized
residents.9,10 Data collected
from each state are pooled to produce nationally representative estimates.9 Further details about the BRFSS have been published.9,10
We calculated body mass index (BMI) (weight in kilograms divided by
the square of height in meters) based on self-reported weight and height.
Participants were classified as obese if their BMI was greater than or equal
to 30 kg/m2.11 Questions on leisure-time
physical activity were included in the BRFSS only in 1991, 1992, 1994, 1996,
and 1998 and were used to create a leisure-time physical activity score: inactive,
irregularly active, regular, not intense, and regular, intense.12
We used SAS and SUDAAN statistical software in the analyses and to account
for the complex sampling design.13,14
Because of the large sample size (more than 100,000 participants each year),
we have not emphasized statistical testing.
We excluded from our trend analyses 6 states because they did not collect
weight and height for 1 or more years: Arkansas (1992), the District of Columbia
(1995), Kansas (1991), Nevada (1991), Rhode Island (1994), and Wyoming (1991,
1992, and 1993). However, we included the data for all available years for
these and all other states in our maps. We used the US Bureau of Census method
of grouping states into regions.
The prevalence of obesity increased from 12.0% in 1991 to 17.9% in 1998
(Table 1). Obesity increased in
men and women and across all sociodemographic groups (Table 2), with the highest increase among the youngest ages and
higher education levels. Among Hispanic men, the prevalence of obesity increased
from 10.0% in 1991 to 18.3% in 1997 and for Hispanic women from 13.2% to 23.4%.
The prevalence of obesity increased steadily from 1991 to 1998 in all states
In 1991, 4 of the 45 participating states had obesity rates of 15% or
higher (Table 3). By 1998, 37
states had rates higher than 15%. The magnitude of the increase varied by
region (ranging from 31.9%-67.2% increase in the mid Atlantic and South Atlantic
regions, respectively) and by state, ranging from 11.3% in Delaware to 101.8%
In 1991, the level of leisure-time physical activity was 29.7% inactive,
28.4% irregularly active, 33.2% regular not intense, and 8.7% regular intense.
In 1998, they were 28.6% inactive, 28.2% irregularly active, 29.6% regular
not intense, and 13.6% regular intense.
To exclude the possibility that demographic differences accounted for
the variation in obesity prevalence between the states, we computed the age-,
sex-, and race-adjusted prevalence of obesity. Although the adjusted rates
were higher than the unadjusted rates, similar patterns were observed among
states and over time. Therefore, we only report the unadjusted estimates.
These data show that obesity increased in every state, in both sexes,
and across all age groups, races, educational levels, and smoking statuses.
Rarely do chronic conditions such as obesity spread with the speed and dispersion
characteristic of a communicable disease epidemic. However, this rapid trajectory
of obesity may present both clues to origin and measures for efficient attempts
to control its spread.
Since overweight participants in self-reported studies tend to underestimate
their weight and all participants tend to overestimate their height; true
rates of obesity are likely underestimated.15,16
Moreover, people without telephones are not surveyed through BRFSS, and such
individuals are likely to be of lower socioeconomic status, a factor that
is associated with obesity.17,18
The net effect of these limitations is that the prevalence of obesity reported
herein is likely a conservative estimate. In fact, the prevalence of obesity
from NHANES III (1988-1994) in which weight and height were measured by health
professionals was 22.5% in adults, more than a third higher than the rates
reported in our survey.3
The BRFSS data provide states with unique population-based estimates
of self-reported obesity against which prevention efforts may be evaluated.
State-level population-based estimates of obesity should be used to provide
each state with a basis for setting priorities for public health interventions.
This rapid increase in obesity in all segments of the population and
regions of the country implies that there have been sweeping changes in US
society that are contributing to weight gain by fostering energy intake imbalance.
Such changes are unlikely to be due to diminished individual motivation to
maintain weight or in genetic or other biological changes in the population.
We focused on describing the changes in patterns of obesity instead
of its contributory factors, such as alterations in diet, activity patterns,
or other behaviors that affect energy balance. However, our data demonstrate
that a major contributor to obesity—physical inactivity—has not
changed substantially at the population level between 1991 and 1998. By focusing
on the challenge of stopping the obesity epidemic and the profound negative
health consequences of obesity, it is important to increase the awareness
and involvement of health professionals in dealing with the epidemic.
Our data suggest that the development of strategies and programs for
weight maintenance as well as weight reduction must become a higher priority.
Public health messages should focus increasingly on balancing energy intake
with physical activity. To control the obesity epidemic, a wide range of population
groups, including physicians and other health care professionals, public health
professionals, legislators, communities, work sites, and organizations, must
become engaged in working toward a solution.
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