Disparities in Overweight and Obesity
Among US College Students
Toben F. Nelson, ScD; Steven L. Gortmaker, PhD; S.V. Subramanian, PhD
Lilian Cheung, ScD; Henry Wechsler, PhD
Objectives: To examine social disparities and behavioral correlates
of overweight and obesity over time
among college students. Methods:
Multilevel analyses of BMI, physical activity, and television viewing
from 2 representative surveys of
US college students (n=24,613).
Results: Overweight and obesity
increased over time and were higher
among males, African Americans,
and students of lower socioeconomic position and lower among
Asians. Television viewing and in
activity were associated with obesity, and disparities in these behaviors partially accounted for excess
weight among African Americans.
Conclusions: Social disparities in
overweight and obesity exist among
college students. Promoting physical activity and reducing television viewing may counteract increasing trends.
Key words: obesity, college students, physical activity, television viewing, social disparities
O
ity racial/ethnic groups, most notably
African Americans and Hispanics.*"® Persons of lower socioeconomic position generally also have higher rates of obesity,^'
Healthy People 2010 goals for the nation's
health include a reduction in the prevalence of obesity and the elimination of
disparities in health across different segments of the population.'"
Obesity is associated with major
chronic diseases, such as cardiovascular disease, some cancers, type 2 diabetes,'''^ and creates a major burden for
health care systems.'^'''^ Although the full
population health consequences of this
epidemic have not yet been realized, the
potential impact for future decreased life
expectancy and poor health due to obesity
is considerable.'* The poor health outcomes of obesity usually manifest in the
later stages of life, but their causes can
develop in childhood or young adulthood.
The transition from adolescence to adulthood is one developmental period that
may be a critical stage for weight gain.
Body mass index (BMI) in early adulthood
is an important predictor for subsequent
verweight and obesity have increased dramatically over the past
30 years among both adults and
children in the United States.''^ The increase in overweight and obesity has
been observed in all age, gender, and
racial/ethnic groups^'^ and is rising more
rapidly among women, young adults, Hispanics and non-Hispanic blacks, and
people with some college education,^'^
Higher rates are observed among minorToben F. Nelson, Research Associate, Department of Society, Human Development and Health;
Steven L. Gortmaker, Professor, Department of
Society, Human Development and Health; S.V.
Subramanian, Assistant Professor, Department
of Society, Human Development and Health; Lilian
Cheung, Lecturer, Department of Nutrition; Henry
Wechsler, Lecturer on Society, Human Development and Health, all from the Harvard School of
Public Health, Boston, MA.
Address correspondence to Dr Nelson, Harvard
School of Public Health, Department of Society,
Human Development and Health, 677 Huntington Avenue, Boston, MA 02115. E-mail:
tnelson@hsph. harvard, edu
Am J Health Behav.™ 2007;31(4):363-373
Am J Health Behav. 2007;31(4):363-373
363
Disparities in Overweight and Obesity
obesity." It is also during the young adulthood period when social patterning in
obesity emerges strongly.^"
In A Call to Action to Prevent and Decrease Overweight and Obesity, the US
Surgeon General recommends schools as
an important setting in which to address
overweight and obesity.'^ To date, most
school-based research and intervention
activity has focused on primary and secondary schools. The college setting presents an important opportunity for health
promotion during a critical stage of development. One in 3 young adults attend
college.^^ However, few studies have examined the prevalence and patterns of
overweight and obesity among college students, and no studies have examined
whether social disparities in overweight
and obesity exist among college students.
Greater caloric intake than expenditure leads to overweight,'^ and specific
behavior targets to prevent and reduce
excess weight include diet and physical
activity.'^'^^'^^ Television viewing also appears to have effects on overweight independent from inactivity.^^ Television viewing is associated with exposure to food
and beverage advertising and with between-meal snacking.^*"^^ Intervention
studies have shovwi that reducing television viewing leads to reductions in overweight and obesity in children.^^"^' The
prevalence of these behaviors and their
relationship to overweight and obesity
has not been systematically studied
among college students.
This study is the first to examine prevalence, trends and social disparities in
overweight, obesity, and class II obesity
in a nationally representative sample of
college students in the United States.
Although other studies have examined
overweight and obesity in this population,
only one obtained a nationally representative sample of students.^" The present
study has sufficient sample size to examine differences among different groups of
students, and it was administered in
multiple years to track changes over time.
We test the hypothesis that the prevalence of overweight and obesity increased
among college students in the United
States from 1993 to 1999. We also examine disparities, or inequalities in overweight and obesity defined by sex, race/
ethnicity, socioeconomic position and age
in this representative sample of college
students. We hypothesize that higher
364
rates of overweight and obesity occur
among males compared with females,
members of minority r a c i a l / e t h n i c
groups, students of lower socioeconomic
position, and upper class (by year in school)
compared with underclass students. The
association of overweight, obesity, and
class II obesity with television viewing
and physical activity, whether these relationships are consistent across student
subgroups, whether they change over
time, and if they account for increasing
body weight or social disparities in these
measures are examined.
METHODS
Sample
Data were from the Harvard School of
Public Health (HSPH) College Alcohol Study
(CAS), a nationally representative sample
of students attending 4-year colleges in
the United States. Colleges were selected
proportionate to the size of the school
from a list of all 4-year institutions provided by the American Council on Education. The sample for the present analysis
included 119 colleges that had data in
both the 1993 and 1999 surveys, consistent with previous analyses of these data.^'
Students were 225 full-time undergraduates randomly sampled within each college. The registrar at each participating
school was provided instructions on drawing a random sample of full-time students. For the present analysis the sample
was limited to 24,613 students (12,786 in
1993 and 11,827 in 1999) under 25 years
of age (mean = 20.4; s.d. = 1.6). Although
these surveys were administered 6 years
apart there is the potential that the same
students could have responded to both,
thereby reducing the variation in the
sample. We did not assess this potential
between the 1993 and 1999 surveys.
However, in other administrations of the
CAS we found an overlap of 1.50% for a 2year difference between surveys and 0.46
% for a 4-year difference between surveys. We have found no statistical evidence of reduced variation resulting from
the inclusion of these respondents.^^
The 1993 and 1999 administrations of
the CAS collected data on exact height
and weight. Response rate was 70% in
1993 (range at each college was 41 to
100%) and was 60% in 1999 (range 4083%). The correlation between response
rate and body mass index at the college
level was r =-0.18 (N=119; P=0.05) in 1993
Nelson et al
and r = -0.16 (N=119; P=0.08) in 1999. All
analyses were adjusted for college response rate to account for response bias,
although it was not statistically significant and did not alter the results. Models
stratified by high and low response rates
showed similar r e s u l t s . Data were
weighted to match each school's true
demographic characteristics over 8 strata
of gender, 2 age-groups (<22 vs others)
and 2 ethnic groups (white vs others).
Additional details of the study methodology and sampling procedure are published
elsewhere.^'
Measures
Respondents reported current height
in feet and inches and weight in pounds.
Self-report measures of height and weight
are generally considered to be valid and
reliable for large-scale surveillance surveys.^^ Three measures were calculated
based on body mass index (BMI), expressed
in kilograms of body weight per meters of
height squared (kg/m^): (a) overweight
(BMI >= 25 kg/m^), (b) obesity (BMI >= 30
kg/m^), and (c) class II obesity (BMI >= 35
k / = ) 3 *
Respondents described the racial/ethnic group they belonged to using the following categories: white; black/African
American; Asian/Pacific Islander; Native American Indian/Native Alaskan;
Other. The Native American and other
race categories were combined due to
small cell sizes for each. Hispanic origin
was included in a separate question and
was modeled separately. Socioeconomic
position (SEP) was assessed as educational attainment for each parent and
converted into a 3-level variable in which
(a) neither parent attended college; (b)
one, but not both, parents attended college; and (c) both parents attended college, consistent with previous analysis of
these data.^^ Students with missing data
on these variables of interest occurred in
less than 1% of the cases, and these were
excluded from the analysis.
Respondents were asked a series of
questions about the amount of time per
day on average they spend on each of 9
different activities, including one question about television viewing and 2 questions about physical activity. Television
viewing was measured as the average
number of hours per day, ranging from
zero to 5 or more. Physical activity was
defined as any participation in intercolleAm J Health Behav.™ 2007;31(4):363-373
giate athletics or other physical activity
(yes vs no). An additional 348 subjects
(.01% of the analytic sample) were missing data for activity, and 97 (.004%) were
missing data for television viewing.
These subjects were deleted from analyses examining television viewing and
activity, and nested models were compared only for those respondents with
complete data.
Analysis
Descriptive analyses and cross-tabulations were conducted in SAS version 9.0
on the UNIX platform (The SAS Institute,
Inc., Cary, NC). Multilevel analytic techniques were used in a 2-level framework
(college and individual) to account for the
clustered sampling scheme in MLwiN
software version 2.0.^* Change over time
in each of the 3 outcome variables was
assessed using an indicator variable for
survey year adjusting for student gender,
race/ethnicity, SEP, and year in school.
Change over time in each group was
examined using interaction terms between survey year and gender, race/
ethnicity, and SEP. Differences in outcome variables for gender over time and
by race/ethnicity were observed, so subsequent analyses were stratified by gender. In gender-stratified models, interaction terms for race/ethnicity with SEP
examined whether SEP modified the association between race/ethnicity and
overweight or obesity. Whether Hispanic
subgroups differed by race was also examined.
Gender-stratified analyses were used
to test for differences between student
subgroups by television viewing and physical activity. Television viewing and physical activity variables were added to each
analysis to examine the relationship of
these variables with overweight and obesity and to determine whether the addition of these variables attenuated the
differences in prevalence of the other
variables. To examine whether the relationship of television viewing and physical activity differed by population groups,
similar models were stratified by race/
ethnicity.
Multilevel logistic regression models
were fitted using the logit-link function
for binomial outcomes, second-order penalized quasi-likelihood and iterative
generalized least squares procedures.
MLwiN employs a Taylor series lineariza-
365
Disparities in Overweight and Obesity
Table 1
Prevalence of Overweight, Obesity and Class II Obesity by
Socio-demographic Characteristics
Sample Size
1993 1999
Overweight
(BMI >=25)
1993 1999
Obesity
Class II obesity
(BMI >=30)
(BMI>=35)
1993 1999 1993 1999
Gender
7369
5417
7258
4569
13.5
30.8
20.1
35.0
2.9
5.4
5.4
7.8
1.0
0.8
2.0
1.8
White 10,624
African American
568
Asian
849
Native American/Other
745
Hispanic
733
9307
633
978
909
743
21.5
33.3
13.6
23.9
25.0
26.7
38.3
16.4
30.6
30.2
3.9
11.2
2.0
3.4
2.8
6.2
13.9
2.3
8.2
8.3
0.7
4.4
0.2
0.6
0.4
1.7
5.3
0.6
2.1
2.2
7454
3256
2076
7412
2841
1574
20.4
23.4
23.5
25.0
29.1
31.4
3.6
4.6
4.9
5.9
7.6
7.2
0.7
1.2
1.2
1.6
2.0
2.9
2864
2648
3110
3045
1119
2993
2845
2912
2382
695
18.9
19.5
22.0
23.8
28.7
23.0
27.3
27.6
27.5
37.2
3.1
4.0
4.3
4.3
5.7
5.2
6.7
7.2
5.7
10.9
0.7
0.8
0.9
1.0
1.2
1.7
2.5
1.5
1.3
Female
Male
Race/ethnicity
Socioeconomic Position
Both Parents Attended College
One Parent (not both) Attended College
Neither Parent Attended College
Year in School
First year
Sophomore
Junior
Senior
Fifth year
tion of the discrete response outcome and
appropriately estimates standard errors
within the multilevel clustered sampling
design.^* Models were specified to account
for college-level variation for each survey
year. The gender-stratified models for the
class II obesity outcome did not converge
under these specifications so a first-order procedure was employed. The analyses using television viewing as the outcome used a normal distribution and the
identity link function. The analyses stratified by race/ethnicity were conducted in
SAS using the generalized estimating
equation (GEE) estimating approach and
the GENMOD procedure.
RESULTS
Overweight rose significantly from
21.7% in 1993 to 26.8% in 1999, adjusting
for gender, race/ethnicity, SEP, and year
in school (adjusted odds ratio 1.33, 95%
confidence interval 1.21-1.46, P<0.001).
Similar increases were noted for obesity
(4.1% in 1993 to 6.5% in 1999; AOR 1.64,
366
3.7
95% CI 1.39-1.93, P<0.001) and class II
obesity (0.9% in 1993 to 1.9%; AOR 1.71,
95% CI 1.27-2.30, P<0.001). Changes
were noted only in weight, whereas height
remained stable.
Overweight, obesity, and class II obesity increased significantly from 1993 to
1999 in all groups, but rates differed by
gender, race/ethnicity, SEP, and year in
school (Table 1). Males were significantly
more likely to be overweight and obese.
However, there was no significant difference by student gender for class II obesity. In gender-stratified analyses, significant differences emerged by race/
ethnicity, SEP, and year in school (Table
2). Among male racial/ethnic groups, overweight was more prevalent among African Americans and Hispanics and less
common among Asians compared with
whites. Among females, similar racial/
ethnic differences emerged, although no
differences existed between Hispanic and
white females. Students of lower SEP had
higher rates of overweight. Higher preva-
Nelson et al
Table 2
Relationship Between Overweight, Obesity, and Class II Obesity
and Socio-demographic Characteristics, Stratified by Gender
Overweight (BMI >=25)
Male
Female
Obesity (BMI>=30)
Male
Female
Class II obesity (BMI>=35)
Male
Female
Year
1993
1999
1.00
1.16(1.03, 1.31)'
1.00
1.51(1.31, 1.75)'"
1.00
1.42(1.11, 1.82)"
1.00
1.99(1.51,2.60)"
1.00
1.88(1.16,3.04)'
1.00
1.49(0.99,2.25)-
Year in School
First year
Sophomore
Junior
Senior
5th year
1.00
1.18 (rO2, 1.36)'
1.36(1.18, 1.56)"'
1.44(1.25, 1.66)*"
1.95(1.60, 2.37)"'
1.00
1.09(0.95, 1.25)
1.05(0.91, 1.21)
1.16(1.01, 1.34)'
1.42(1.14, 1.77)"
1.00
1.16(0.88, 1.53)
1.40(1.06, 1.84)"
1.26(0.95, 1.66)1.97(1.38,2.79)'"
1.00
1.44(1.10, 1.90)"
1.41 (1.05, 1.89)'
1.33(0.96, 1.84)~
2.00(1.31,3.06)"'
1.00
1.05(0.60, 1.83)
1.07(0.62, 1.84)
1.47(0.86,2.53)
2.59(1.41,4.77)"
1.00
1.63(1.08,2.45)'
1.25(0.77,2.04)
0.96(0.60, 1.53)
2.01 (1.05, 3.84)'
White
1.00
African American
1.48(1.15,1.90)'"
Asian 0.59 (0.48, 0 . 7 3 ) ' "
Native American/Other 0.91 (0.71, 1.17)
Hispanic
1.27(1.04,1.56)'
1.00
2.32(1.94,2.78)'"
0 47(0.37,0.61)'"
1.38(1.10, 1.75)"
0.98(0.76, 1.26)
1.00
2.22(1.46,3.35)'"
0.54 (0.30, 0.97)"
1.11(0.77, 1.36)
1.02(0.77, 1.56)
1.00
3.22(2.38,4.35)"'
0.35(0.18,0.65)'"
1.44(0.89,2.35)
0.85(0.50, 1.44)
1.00
3.57(2.13,5.99)'"
0.76(0.35, 1.67)
1.37(0.63,2.99)
0.80(0.33, 1.97)
1.00
3.57(2.38,5.36)"'
0.08(0.01,0.65)"
1.36(0.55,3.35)
0.76(0.32, 1.82)
Race/ethnicily
Socioeconomic Position
Both Parents
Attended College
1.00
One Parent (not both)
Attended College
1.18(1.05, 1.32)"
Neither Parent
Attended College
Note.
1.17(1.03,1.34)'
1.00
1.00
1.00
1.00
1.00
1.22(1.08, 1.37)"
1.16(0.88, 1.53)
1.32(1.08, 1.62)"
1.40(0.93,2.11)
1.16(0.80, 1.67)
1.45(1.26, 1.67)'"
1.02(0.77, 1.36)
1.67(1.24,2.25)'"
1.30(0.78,2.15)
1.90(1.29,2.80)"'
~P<.10; *P<.05; **P<.01; ***P<.001
lence rates of overweight were observed
in successive years in school. Neither
racial/ethnic differences by SEP nor racial differences among subgroups of Hispanics were observed. A similar pattern
in the trends and differences between
student subgroups for obesity and class II
obesity emerged.
Student Behaviors
Approximately 3 in 4 students reported
engaging in some form of moderate or
vigorous physical activity in both 1993
(75%) and in 1999 (74%). Males were
more likely to be physicaJly active compared with females (80% vs 70% in 1993;
P<0.0001; and 78% vs 71% in 1999;
P<0.0001). Students reported watching
an average of 2 hours of television per
day, and this did not differ for males and
females. There was no significant difference in reported physical activity or television viewing by survey year. African
American students reported more television viewing than did other racial/ethnic
groups among males (2.8 hours per day;
s.d. = 1.7 compared with 2.1 hours overall;
s.d. = 1.4; AOR 2.85; 95% CI 1.24 - 6.54).
Am J Health Behav.™ 2007;31(4):363-373
Students of lower SEP watched significantly more television among males (2.3
hours; s.d. = 1.5; AOR 1.91; 95% CI 1.19 3.07 for neither low SEP, and 2.2 hours;
s.d. = 1.5; AOR 1.68; 95% CI 1.05-2.71 for
mid SEP compared with high SEP). No
significant differences in physical activity by race/ethnicity or SEP were observed for physical activity among males
or females. Although the average number of hours of television viewing among
African American females was also higher
(2.9 hours per day; s.d. = 1.6 compared
with 1.9 hours overall; s.d. = 1.3), these
results were not statistically significant
(AOR 2.03; 95% CI 0.87 - 4.72). Among
females, physical activity was less prevalent for African Americans (55.6% compared with 70.9 % overall; AOR 0.50; 95%
CI 0.43 - 0.59) and Asians (62.9%; AOR
0.63; 95% CI 0.54 - 0.74) and students of
low SEP (64.2%; AOR 0.76; 95% CI 0.67 0.86 for low SEP; 68.4%; AOR 0.85; 95% CI
0.79 - 0.93 for mid SEP compared with
high SEP, 73.1%).
The association of overweight and obesity with both physical activity and television viewing was examined in gender-
367
Disparities in Overweight and Obesity
Tahle 3
Prevalence of Overweight, Ohesity and Class II Ohesity hy
Survey Year, Gender, Physical Activity, and Average
Daily Television Viewing
Overall
Male
Female
1993
1999
1993
1999
by Physical Activity
Not
Active
Active
by Average Daily Television Viewing
0 hrs.
lhr.
2-hrs
3 hrs.
4+ hrs.
79.7
78.1
70.4
70.4
20.3
21.9
29.6
29.6
11.3
11.4
13.7
14.2
29.0
29.2
28.9
32.2
26.0
26.8
25.7
24.9
16.4
17.0
15.9
14.6
17.4
15.6
15.8
14.1
% Overweight
Male 1993
1999
Female 1993
1999
30.8
35.0
13.5
20.1
31.0
34.4
12.5
18.2
30.0
37.5
15.8
24.9
22.3
26.1
9.4
13.5
26.8
32.9
11.3
17.5
30.2
35.7
13.3
20.6
35.0
39.9
14.9
23.6
40.0
39.5
19.2
28.3
% Obese
Male 1993
1999
Female 1993
1999
5.4
7.8
2.9
5.4
4.9
4.2
2.4
6.9
7.2
8.3
4.1
10.9
2.2
4.4
1.4
1.9
3.2
5.8
2.1
3.9
5.1
7.1
2.8
6.8
6.9
9.5
3.3
6.0
10.1
13.6
5.2
9.2
% Class II Obesity
Male 1993
1999
Female 1993
1999
0.8
1.8
1.0
2.0
0.7
1.5
0.6
1.2
1.0
2.8
1.8
3.9
0.6
1.0
0.5
1.0
0.3
0.9
0.8
1.3
0.6
2.0
0.9
1.1
0.8
2.0
0.7
1.9
2.0
3.4
2.1
3.4
stratified analyses adjusting for survey
yeeir, race/ethnicity, and SEP. Television viewing was positively associated
with overweight among males (AOR 1.14,
95% CI 1.11 - 1.18) and females (AOR 1.16,
95% CI 1.12 - 1.20). Similar findings were
observed for obesity (AOR 1.31, 95% CI
1.24 - 1.39 for males and AOR 1.22, 95% CI
1.14 - 1.29 for females) and class II obesity
(AOR 1.31, 95% CI 1.16 - 1.48 for males
and AOR 1.16, 95% CI 1.03 - 1.32 for
females). Students who engaged in physical activity were less likely to be overweight among females (AOR 0.75, 95% CI
0.68 - 0.84, adjusting for television viewing), but not among males. Physically
active students were less likely to be
obese among both females (AOR 0.56,
95% CI 0.47 - 0.67) and males (AOR 0.63,
95% CI 0.52 - 0.76) and were less likely to
meet criteria for class II obesity among
both females (AOR 0.33, 95% CI 0.23 0.46) and males (AOR 0.59, 95% CI 0.40 -
368
0.87). The relationships of physical activity and television viewing with overweight,
obesity, and class II obesity were similar
in each survey year and were consistent
with overall findings across racial/ethnic groups. No significant interaction
effects for any of the race/ethnicity categories with physical activity or television viewing for overweight, obesity, and
class II obesity in the gender stratified
multilevel models were observed.
Adding the physical activity and television viewing variables to the analyses
improved the overall model fit and reduced the odds of overweight for African
Americans in the model for females (from
AOR = 2.32; 95% CI 1.94 - 2.78 to AOR =
1.93; 95% CI 1.61 - 2.33) and for males
(from AOR = 2.32; 95% CI 1.94 - 2.78 to
AOR = 1.93; 95% CI 1.61 - 2.33), although
African Americans remained at significantly higher odds of being overweight in
nested models of students with complete
Nelson et al
data. Physical activity and television viewing did not appear to account for other
disparities in overweight by r a c e /
ethnicity or SEP, or changes in the prevalence of overweight over time. Similar
results for obesity were observed, with
declines in the odds for African American
females from AOR = 3.25 (95% CI 2.55 4.15) to AOR = 2.49 (95% CI 1.93 - 3.20) and
for African American males from AOR =
1.98 (95% CI 1.42 - 2.75) to AOR = 1.69
(95% CI 1.21 - 2.37) when accounting for
physical activity and television viewing,
but no other shifts in odds for any of the
other groups. Similar declines in the
odds of class II obesity for both female
(from AOR = 3.56; 95% CI 2.37 - 5.34 to
AOR = 2.59; 95% CI 1.68 - 3.98) and male
(from AOR = 3.48; 95% CI 2.00 - 6.04 to
AOR = 2.96; 95% CI 1.69 - 5.19) African
American students were observed. No
other changes were noted when accounting for physical activity and television
viewing in the models.
DISCUSSION
A substantial number of college students are overweight and the prevalence,
like that in the US population overall,''^'^'
has increased over time. Class II obesity
rose rapidly during the study period, which
is particularly concerning considering the
substantial health care costs associated
with extreme obesity.'^••'^
Male college students were more likely
to be overweight and obese than their
female peers, consistent with findings in
other surveys of youth and adults.'•^•^°'^'''°
However, there were no differences in
class II obesity between males and females. Females report greater concern
about their weight and may expend more
effort to maintain or lose weight through
dietary control and exercise.^" Socioeconomic position was associated with overweight, obesity, and class II obesity among
both males and females, although the
strength of this association was stronger
among females. These results are consistent with findings across multiple agegroups that show differences in rates of
overweight and obesity by gender and
socioeconomic position."" People of higher
socioeconomic position tend to have
greater awareness of weight and expend
more effort at maintaining weight through
dietary control and physical activity, which
may explain these differences.'""''^ Females could also be more likely to be
Am J Health Behav.™ 2007;31(4):363-373
accepted into college if they are thin or of
normal weight, compared with males. A
third factor that promotes both academic
achievement and interest in weight control may account for lower rates of overweight among females. These social
forces apply to both males and females,
although they may apply differentially to
males. Females may also experience
disproportionate weight-related discrimination compared with males and experience negative social consequences as a
result.""
Higher rates of overweight and obesity
were observed among male and female
African American students, consistent
with other studies.2''° These racial/ethnic disparities emerged in a sample adjusted for parent socioeconomic position
and restricted to college students, itself
an indicator of higher socioeconomic position. We found lower rates of overweight
and obesity among Asian students. However, the relationship between BMI and
cardiovascular disease may vary by racial/ethnic group."5"^ Prevalence rates
for overweight in both survey years and
obesity in the 1999 survey year were
higher among Hispanics compared with
whites, but these differences were not
significant when adjusting for socioeconomic position. These findings are different from those observed in other studies'''^'' and may refiect socioeconomic differences. In the CAS sample, more Hispanic students reported that neither parent attended college (27%) compared with
students overall (14%).
Significantly higher rates of overweight
and obesity occurred among students in
their later years of college in both surveys. However, these data are crosssectional, and hypotheses about the
course of weight gain during college cannot be adequately addressed with this
design. Longitudinal studies tracking individuEil students throughout their college years may provide more insight into
the factors that promote healthy weight
maintenance. One limitation of the
present study was that the CAS was administered in the spring of the school
year and may have missed significant
weight gain occurring upon entry to college.
Late adolescence and early adulthood
may be a time of particular risk for weight
gain beyond normal and healthy development. Data from the CDC Youth Risk
369
Disparities in Overweight and Obesity
Behaviors Survey show that in 1999, approximately 12% of male and 8% of female
high school students in the United States
were overweight.''* Among young adults
aged 1 8 - 2 4 years, 37% of males and 21%
of females were overweight in 1993, and
these estimates rose to 42% for males
and 28% for females in 1999.''^'5° The lower
overall prevalence rates in the present
study compared with the BRFSS and with
data from the National College Health
Risk Behavior Survey may reflect the
higher socioeconomic position of young
adults who attend college compared to
those who do not attend college and vnth
students who attend 4-year colleges, compared with students who attend all types
g
Physical activity, diet, and television
viewing are 3 important behavioral targets to prevent or counteract overweight
and obesity.'^ Females who were active
were less likely to be overweight, whereas
there was no significant relationship between physical activity and overweight
among males. Both males and females
who engaged in moderate or vigorous
activity were less likely to be obese. Hours
of television vievwng were strongly associated with being overweight, consistent
with findings in other populations,^''^^ and
may reflect the role of heavy advertising
of calorie-dense, low-nutrient foods on
television.^'' The average college student
reports watching 2 hours of television per
day. African American students reported
watching an average of nearly 3 hours of
television per day. Considering findings
from other studies that show reducing
television viewing prevents weight gain,^''"
^' this is a promising behavioral target for
preventing overweight and obesity among
college students.
Activity or television-viewing behaviors did not change over time and are not
likely to be driving the changes in body
weight in the college student population
over time. They also do not appear to
account for between-group differences in
body mass. Adjusting for these behaviors
reduced the magnitude of the observed
disparities in overweight among African
American males and females, suggesting
that those behaviors may account for
some racial disparities in overweight and
obesity. However, adding the activity and
television-viewing variables did not
eliminat disparities in this group and did
not change estimates for the other ra-
370
cial/ethnic or socioeconomic groups. It
is possible that the content of the television viewed differed for some groups compared with others and these exposure
differences could account for the remaining social disparities in overweight and
obesity. For example, television programming viewed more frequently by African
American students may contain more
advertisements for calorie-dense fast food,
promoting its consumption. Consuming
fast food is associated with increased
intake of overall calories, dietary fat, carbohydrate, added sugars, and sugar-sweetened beverages among children.^^ Future
research among college students could
benefit from increased measurement precision and longitudinal research design.
Some caveats and potential limitations
should be considered when examining
this evidence. Self-report height and
weight are subject to reporting bias Eind
may lead to lower estimated BMI compared to measured height and weight.^^'^"*
As a result, our findings may reflect lower
rates of overweight and obesity than the
true prevalence of these conditions in the
population. In addition, females are more
likely to underreport their weight compared with males, and this may at least
partly explain the differences we observed
between males and females.^^'^* However,
self-reported heights and weights are generally considered valid and can be reliably
used in large-scale national survey research, particularly with young adults.^^
In addition, we did not have measures of
height and weight prior to students entering college to examine changes during
college. The measures of physical activity and television viewing were limited to
single questions and may not provide a
complete reflection of students' behavior.
The imprecision of these variables may
have reduced our ability to estimate the
true prevalence in the college student
population and to examine the complex
relationship vwth overweight and obesity
by student subgroups. However, physical
activity and television viewing were associated with overweight and obesity in
this sample, consistent with existing literature,^^'^'' and the prevalence rates for
these measures were consistent across
survey years. Nonresponse bias may have
influenced the results. However, body
mass index was not correlated with survey response rate, the results did not
differ when adjusting for college response
Nelson et al
rate, and models stratified by high and low
response rate were similar. Prevalence
rates were consistent with other studjgg 39,40 Possible mechanisms not tested
in this study include dietary behavior,
self-perceived weight, ideal body size, discrimination, and social isolation. We did
not collect dietary consumption data, and
this represents an area for future research £ind prevention efforts in the college student population.
Young people in the transition from
adolescence to adulthood are at risk for
excess weight gain. Students entering
college may be making independent decisions about their diet, activity, and television viewing behaviors for the first time.
New environmental and social factors
may emerge during this time period to
have a greater influence on their behavior.^^ Understanding these influences on
student behavior and the environments
in which they live may help prevent the
epidemic of overweight and obesity. Additional studies should investigate potential mechanisms that may create social
disparities in overweight and obesity
among college students. Future work
should also consider to what extent these
mechanisms are unique to the college
setting or whether some aspects of college life may be amenable to change to
reduce overweight and obesity. The
present study suggests that reducing television viewing and increasing physical
activity may help counteract overweight
and obesity, but they are not likely the
fundamental causes of the increase in
prevalence we observed in this study.
Additional study using measures of
height, weight, television viewing, and
physical activity that allows greater precision may help inform these questions.
Dietary intake and the food environment
at college are also potential topics for
further investigation. Parents, college
administrators and staff, peers, and other
health professionals can engage students
in understanding the components of
maintaining healthy weight and can
shape environments so students are more
likely to engage in healthy behaviors that
affect their weight.
Acknowle dgment
This research was supported by grants
from the Robert Wood Johnson Foundation to H. Wechsler and by the Centers for
Disease Control and Prevention, PrevenAm J Health Behav.™ 2007;31(4):363-373
tion Research Centers.
•
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