weight-control behaviors among adolescent girls and boys: implications for dietary intake
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RESEARCHurrent Research
eight-Control Behaviors among Adolescentirls and Boys: Implications for Dietary Intake
IANNE NEUMARK-SZTAINER, PhD, MPH, RD; PETER J. HANNAN, MStat; MARY STORY, PhD, RD; CHERYL L. PERRY, PhD
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BSTRACTbjective To examine associations between healthful andnhealthful weight-control behaviors and dietary intakemong adolescents.esign Cross-sectional survey (Project EAT [Eatingmong Teens]).ubjects/Setting The study population included 4,144 mid-le and high school students from Minneapolis/St. Paulublic schools from diverse racial and socioeconomicackgrounds.tatistical Analyses Dietary intake patterns were comparedcross adolescent girls and boys reporting unhealthful,nly healthful, or no weight-control behaviors in unad-usted analyses and analyses adjusted for sociodemo-raphic factors and energy intake.esults Among girls, mean intakes differed across weight-ontrol behaviors for all foods and nutrients examined. Palues ranged from P�.006 to P�.001. Girls using un-ealthful weight-control behaviors had significantly
ower intakes of fruit; vegetables; grains; calcium; iron;itamins A, C, and B-6; folate; and zinc than girls usingnly healthful weight-control behaviors. Compared withirls reporting no weight-control behaviors, girls usingnhealthful weight-control behaviors had lower intakesf grains, calcium, iron, vitamin B-6, folate, and zinc. Inontrast to the girls, boys reporting unhealthful weight-ontrol behaviors did not have poorer dietary intakeshan boys not using weight-control behaviors or usingnly healthful behaviors. Among boys, there were no sig-ificant differences in mean intakes of vegetables; grains;alcium; iron; vitamins A, C, and B-6; folate; and zinc.urthermore, boys using unhealthful weight-control be-aviors had higher fruit intakes (P�.002) than boys re-orting no weight-control behaviors.onclusions Adolescent girls who engage in unhealthfuleight-control behaviors are at increased risk for dietary
nadequacy. The findings demonstrate a need for inter-entions to prevent unhealthful weight-control behaviors
. Neumark-Sztainer, P. J. Hannan, M. Story, and
. L. Perry are with the Division of Epidemiology,chool of Public Health, University of Minnesota, Min-eapolis.Address correspondence to: Dianne Neumark-Sztainer,
hD, MPH, RD, Division of Epidemiology, School ofublic Health, University of Minnesota, 1300 S Secondt, Suite 300, Minneapolis, MN 55454. E-mail: [email protected]
Copyright © 2004 by the American Dietetic Association.0002-8223/04/10406-0006$30.00/0
edoi: 10.1016/j.jada.2004.03.021
2004 by the American Dietetic Association
n adolescent girls, and to promote healthful weight-con-rol behaviors when indicated.Am Diet Assoc. 2004;104:913-920.
ata from numerous studies have demonstrated ahigh prevalence of weight-control behaviors amongadolescents, particularly adolescent girls (1-3). In
reviously reported findings from the Project EAT (Eat-ng Among Teens) study, 45% of adolescent girls and 21%f adolescent boys reported that they were currently try-ng to lose weight, and an additional 26% of girls and 23%f boys were trying to maintain their weight (4,5). Ofarticular concern were the high percentages of youthho reported using unhealthful weight-control behaviors.nhealthful weight-control behaviors such as skippingeals, fasting, using food substitutes, or smoking more
igarettes were reported by more than half (57%) of theirls and by one third (33%) of the boys. An additional2% of girls and 5% of boys reported extremely unhealth-ul behaviors such as use of diet pills, laxatives, diuretics,r vomiting.Some weight-control behaviors (eg, increasing fruits
nd vegetables and decreasing foods high in fats andugars) are appropriate, even desirable, for most adoles-ents, when done in moderation. These behaviors havehe potential to help adolescents achieve a healthful bodyeight through the prevention of excess weight gain or,hen appropriate, through gradual weight loss. However,ecause of the importance of adequate nutrition duringdolescence (6-9), it is essential to determine the poten-ial implications of different weight-control behaviors onietary intake in youth. On one hand, there may be pos-tive implications if adolescents become more attentiveaters, consume more fruits, vegetables, and wholerains, and avoid excessive fat intake. On the other hand,here may be negative implications if energy restrictionsr selective food choices lead to decreased intake of nu-rients such as iron and calcium, which are importanturing this period of growth and development (10,11). Touide the development of appropriate messages and di-tary intervention programs for youth, it is important toetermine whether weight-control behaviors are associ-ted with dietary intake and whether associations varyor different types of weight-control behaviors.
In general, studies have suggested that youth engagingn weight-control behaviors (unhealthful weight-controlehaviors in particular), are at risk for inadequate di-tary intakes (12-17), although in some studies associa-ions were not found (18-20), and in other studies weight-ontrol behaviors were associated with more positive
ating patterns such as decreased consumption of high-Journal of THE AMERICAN DIETETIC ASSOCIATION 913
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at baked goods (ie, cookies, doughnuts, pie, or cake) (21),weets, salty snacks, and soft drinks (22). Inconsistenciesay be due to differences in measures used to assesseight-control behaviors, dietary assessment tools, di-tary components being examined, and sample character-stics and sizes. Many of the studies that have examinedssociations between weight-control behaviors and di-tary intake did not distinguish between different typesf weight-control behaviors (16,18,21,23), used inade-uate measures of dietary intake (15,16,21-23), had smallamples (or small numbers of dieters within samples)12-14,19), or included only girls in their study popula-ions (12,17,20).
The current study explores associations betweeneight-control behaviors and dietary intake. It expandsn existing studies exploring these associations in thatata are drawn from a large, ethnically diverse popula-ion of adolescents. In addition, healthful weight-controlehaviors, unhealthful weight-control behaviors, and aroad array of dietary outcomes are examined. Specifi-ally, the current study compares intake patterns of keyoods and nutrients among adolescent girls and boys re-orting no weight-control behaviors in the past year, onlyealthful weight-related behaviors, or unhealthfuleight-control behaviors. Mean dietary intakes and per-
entages of adolescent girls and boys meeting dietaryecommendations are examined across these threeroups. The current study further explores whether as-ociations between weight-control behaviors and dietaryntake differ across race/ethnicity and weight status ofdolescent girls and boys.
ETHODStudy Population and Study Designhe overall study population included 4,746 adolescents
rom 31 public middle schools and high schools fromrban and suburban school districts in the St Paul/Min-eapolis area of Minnesota who participated in ProjectAT. Trained research staff administered surveys withinchool classes and assessed height and weight within arivate area. Study procedures were approved by theniversity of Minnesota Human Subjects Committeend by the research boards of the participating schoolistricts. Consent procedures were done in accordanceith the requests of the participating school districts; in
ome schools passive consent procedures were utilized,hereas active consent procedures were required in oth-rs. The response rate for student participation was1.5%. Further details on the study sample and designave been previously published (24-26).Participants who did not complete the food frequency
uestionnaire (n�344) were not included in the currentnalysis. In addition, participants who had energy in-akes less than 400 kcal/day or more than 7,000 kcal/dayn�258) were excluded from analyses examining associ-tions with dietary intake because these values are con-idered biologically implausible for habitual intake.hus, the final study population in the current analysis
ncluded 4,144 participants.The adolescents included in the current analysis were
ompared with those who were excluded due to missing or
nusable dietary intake data and found to be similar in t14 June 2004 Volume 104 Number 6
erms of sex and body mass index (BMI), but more likelyo be white, of higher socioeconomic status, and in middlechool (rather than high school). These differences wereot expected to strongly influence associations betweeneight control practices and dietary intake that are being
xplored in the analyses.
easureseight-control behaviors over the past year were as-
essed with the question: “Have you done any of theollowing things in order to lose weight or keep fromaining weight during the past year?” (yes/no for eachethod). Responses classified as healthful weight-control
ehaviors included lifestyle behaviors recommended forll adolescents for overall health promotion and weightanagement: (a) exercise, (b) ate more fruits and vege-
ables, (c) ate less high-fat foods, and (d) ate less sweets.esponses classified as unhealthful weight-control be-aviors included: (a) fasted, (b) ate very little food, (c)sed food substitute (powder/special drink), (d) skippedeals, (e) smoked more cigarettes, (f) took diet pills, (g)ade myself vomit, (h) used laxatives, and (i) used di-
retics. Respondents were classified as using healthfuleight-control behaviors if they reported any of theealthful behaviors and no unhealthful behaviors. Theyere categorized as using unhealthful weight-control be-aviors if they reported any of the unhealthful behaviors.ost of the youth using unhealthful weight-control be-
aviors also reported the use of healthful weight-controlehaviors; therefore, mutually exclusive groups were notossible. For the majority of specific weight-control be-aviors used in the past year, test-retest � values over a-week interval ranged from 0.50 to 0.68, but lower val-es were found for laxatives (0.29) and food substitutes0.44). Dietary intake was assessed with the Youth anddolescent Food Frequency Questionnaire (27,28). Serv-
ngs of fruits, vegetables (including and not includingrench fries), grains (eg, cereal, bread, pasta, rice), andweet and salty snack foods (eg, potato chips, candy, cake,nd cookies) were examined in addition to the followingutrients: energy (kcal), total fat (% of total energy),aturated fat (% of total energy), protein (% of total en-rgy), carbohydrate (% of total energy), calcium (mg), ironmg), vitamin A (IU), vitamin C (mg), vitamin B-6 (mg),olate (�g), and zinc (mg). In addition to examining meanntakes, we also examined the percentages of youth meet-ng the Healthy People 2010 objectives for fruits, vegeta-les, and grains (29), and the Dietary Reference IntakesDRI) for macronutrients and micronutrients (30-32).
Sex, school level, ethnicity/race, and socioeconomictatus (SES) were based on self-report (24). BMI wasased on height and weight measurements taken by re-earch staff using standardized equipment and proce-ures.
ata Analysisirls and boys were analyzed separately due to sexifferences in weight-control behaviors. Analyses of vari-nce generated mean outcomes for adolescents reportingo weight-control behaviors, only healthful weight-con-
rol behaviors, or unhealthful weight-control behaviors.
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o allow for the clustered design, the school was includedn all analyses as a random effect. For skewed outcomesuch as servings of fruits and vegetables, the square rootf the outcome was analyzed; however, means are re-orted on the natural scale for all outcomes. The percentf students meeting the various Year 2010 objectivesere treated as continuous measures. Analysis was byROC MIXED (SAS, Release 8.2).Covariates used in adjusted analyses were grade (mid-
le vs high school), ethnicity/race (white, African Ameri-an, Hispanic, Asian American, other), and SES (fiveevels). Analyses examining mean intakes of foods andutrients were further adjusted for energy intake, butnalyses examining the percentages of adolescents eatingccording to dietary recommendations were not energy-djusted because most dietary recommendations are con-istent across energy intake. Further energy adjustmentsor macronutrients were not done because they are re-orted as percentages of total energy intake in all anal-ses. Results from unadjusted analyses are presented inhe tables; findings from adjusted analyses are discussedn the text.
The possibility of confounding of the relationship be-ween dietary intake and weight control methods by race/thnicity was examined by including the interaction oface/ethnicity (five categories) with weight-control behav-or (three categories) in the adjusted analyses. A signifi-ance level of less than .01 was required for the global-test [8 degrees of freedom (df)]. Where the global testas significant, more specific post hoc hypotheses werexamined comparing each of the four minority racial/thnic groups against the majority white group (2 df).djusted means were generated to describe the pattern of
nteraction. For weight status as a possible confounder,verweight was defined as BMI at or more than the 85thercentile, and the main effect for overweight and inter-ction of overweight with weight-control methods weredded to the adjusted model. Again, a significance leveless than .01 was required for the global test of interac-ion (2 df test).
ESULTSescription of Study Populationable 1 provides a description of the study population inerms of age, BMI, ethnicity/race, SES, and weight-con-rol behaviors. More than half of the girls (57.2%) andearly one third of the boys (31.6%) reported the use of at
east one unhealthful weight-control behavior over theast year.
ean Dietary Intake by Weight-Control Behaviorsn general, girls using unhealthful weight-control behav-ors had poorer dietary intakes than girls reporting noeight-control behaviors or only healthful behaviors (Ta-le 2). Girls using unhealthful weight-control behaviorsad significantly lower intakes of fruit, vegetables,rains, and all micronutrients examined (calcium; iron;itamins A, C, and B-6; folate; and zinc) than girls usingnly healthful weight-control behaviors. Compared withirls reporting no weight-control behaviors, girls using
nhealthful weight-control behaviors had lower intakes wf grains and certain micronutrients (calcium, iron, vita-in B-6, folate, and zinc). Analyses adjusting for ethnic-
ty/race, SES, and school level found similar patternsdata not shown in tables).
In energy-adjusted analyses, differences between girlssing unhealthful and healthful weight-control behaviorsemained statistically significant for calcium, iron, vita-ins A and B-6, folate, and zinc, with lower intakes
mong girls using unhealthful behaviors, but differencesetween girls using unhealthful behaviors and no weight-ontrol behaviors were no longer statistically significantor these nutrients (data not shown). Girls using onlyealthful weight-control behaviors had higher fruit in-ake than girls not using weight-control behaviors andigher vitamin A intake than both of the other groups.ssociations between weight-control behaviors and serv-
ngs of vegetables, grains, snack foods, and vitamin Cere no longer statistically significant. Other findings
rom energy-adjusted analyses were similar to thosehown in Table 2 for unadjusted analyses.In contrast to the girls, boys reporting unhealthful
Table 1. Description of study population: Body mass index, socio-demographic characteristics, and weight-control behaviors
Adolescentgirls(N�2,064a)
Adolescentboys(N�2,080a)
Mean SDb Mean SDAge (y) 14.8 1.67 14.9 1.65BMIc 23.2 4.94 23.0 4.81
N % N %Race/ethnicity
White 997 49.1 1,120 54.4African American 340 16.7 316 15.4Hispanic 100 4.9 123 6.0Asian American 426 20.9 377 18.4Native American 85 4.2 58 2.8Mixed/other 86 4.2 61 3.0
SESd
High 274 13.7 297 14.7High-middle 448 22.3 528 26.0Middle 519 25.8 552 27.2Low-middle 382 19.0 372 18.4Low 386 19.2 278 13.7
Grade levelMiddle school 680 33.4 675 32.8High school 1,358 66.6 1,385 67.2
Weight-controlbehaviors
None 253 12.4 610 29.6Healthful only 622 30.5 798 38.8Unhealthful 1,168 57.1 650 31.6
aDue to missing values for certain variables, numbers do not always add up to thismaximum N.bSD�standard deviation.cBMI�body mass index.dSES�socioeconomic status.
eight-control behaviors did not have poorer dietary in-
Journal of THE AMERICAN DIETETIC ASSOCIATION 915
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akes than boys not using weight-control behaviors orsing only healthful behaviors (Table 3). Fruit intake wasighest among boys reporting unhealthful weight-controlehaviors and lowest among boys reporting no weight-ontrol behaviors, being intermediate in boys using onlyealthful weight-control behaviors. Total fat and satu-ated fat intakes, as percentages of energy, were lowermong boys using healthful and unhealthful weight-con-rol behaviors than among boys not trying to control theireight. There were no differences in intakes of vegeta-les, protein, or carbohydrate (as percentages of energyntake), or any of the micronutrients examined (calcium;ron; vitamins A, C, and B-6; folate; and zinc) acrosseight-control behaviors. Similar analyses on boys werelso run, adjusting for ethnicity/race, SES, and schoolevel, and similar patterns were found (data not shown).
Energy-adjusted analyses in boys further suggest thatoys engaging in weight-control behaviors, particularlyealthful behaviors, may have a higher quality of dietary
ntake than boys not engaging in weight-control behav-ors (data not shown). Fruit and folate intake were highern boys using healthful and unhealthful weight-controlehaviors, and snack intake was lower, than in boys notsing weight-control behaviors. Iron and vitamin B-6 in-akes were higher in boys using healthful weight-controlehaviors than in both of the other groups. Finally, zincntake was higher in boys using healthful weight-controlehaviors than in those using unhealthful weight-controlehaviors. All other findings from energy-adjusted anal-ses were similar to those found in unadjusted analyses
Table 2. Dietary intake (mean/day) by types of weight-control behav
None(N�253)
4™™™™™™™Energy (kcal) 2,268�79Fruits (servings) 2.40�0.1Vegetables (servings not including french fries) 1.94�0.1Vegetables (servings including french fries) 2.12�0.1Grains (servings) 6.4�0.2Sweet/salty snack foods (servings) 3.3�0.2Total fat (% of energy) 30.6�0.4Saturated fat (% of energy) 11.0�0.2Protein (% of energy) 14.4�0.2Carbohydrate (% of energy) 56.4�0.4Calcium (mg) 1,163�44Iron (mg) 16.2�0.6Vitamin A (IU) 9,526�50Vitamin C (mg) 163.2�7.1Vitamin B-6 (mg) 1.88�0.0Folate (�g) 337.1�12Zinc (mg) 12.4�0.4
aP values are for transformed variables (except for macronutrients as % of energy andbSE�standard error.x,yDifferent superscripts indicate statistically significant differences using Bonferroni adj
hown in Table 3. n
16 June 2004 Volume 104 Number 6
ercentages of Youth Eating According to Dietary Guidelines byeight-Control Behaviorsirls using unhealthful weight-control behaviors were
ess likely to meet dietary recommendations for most ofhe micronutrients examined (calcium, iron, vitamins Cnd B-6, folate, and zinc) than girls using no weight-ontrol behaviors or only healthful behaviors. In addition,irls using unhealthful weight-control behaviors wereess likely to consume the recommended amounts ofruits, vegetables, and grains than girls using healthfuleight-control behaviors (Table 4). Only one fourth
25.7%) of girls using unhealthful weight-control behav-ors consumed 1,300 mg/day or more of calcium, and onlyne third (33.4%) met dietary recommendations for ironntake. Analyses adjusting for race/ethnicity, SES, andchool level revealed similar patterns (data not shown).Compared with girls, among boys there were fewer
ifferences across weight-control behaviors, and differ-nces were not consistent in their direction (Table 5). Forxample, boys using unhealthful weight-control behav-ors were less likely to meet dietary recommendations forron but were more likely to meet recommendations forruit, vegetable, and saturated fat intakes than boys notngaging in weight-control behaviors.Among the boys, in analyses adjusting for race/ethnic-
ty, SES, and school level, patterns were similar to thosehown in Table 5 except for fruit, iron, and total fatntakes. For fruit and iron intake, differences acrosseight-control behaviors were no longer statistically sig-
used in the past year in adolescent girls
Weight-Control Behaviors
P valueaHealthful only(N�622)
Unhealthful(N�1,168)
™™™™™™™™™mean�SE b™™™™™™™™™™™™™™™™™32,165�63x 1,997�57y �.0012.59�0.11x 2.35�0.09y .0112.01�0.08x 1.76�0.07y �.0012.17�0.08x 1.92�0.07y .0026.0�0.2x 5.5�0.2y �.0013.0�0.2x,y 2.7�0.1y .004
30.0�0.3x,y 29.4�0.3y .00610.7�0.1x 10.3�0.1y �.00114.7�0.2x 14.0�0.1y �.00156.8�0.3x 57.8�0.2y .002
1,132�34x 974�30y �.00115.8�0.4x 13.8�0.4y �.001
10,012�390x 8,660�346y �.001166.2�5.1x 152.2�4.3y .0171.84�0.05x 1.62�0.04y �.001
334.7�9.4x 292.2�8.0y �.00112.2�0.3x 10.6�0.2y �.001
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eight-control behaviors met dietary recommendationsor total fat intake than boys reporting no weight-controlehaviors (P�.027).
Table 3. Dietary intake (mean/day) by types of weight-control behav
None(N�610)
4™™™™™™Energy (kcal) 2,301�72Fruits (servings) 2.12�0.Vegetables (servings not including french fries) 1.61�0.Vegetables (servings including french fries) 1.80�0.Grains (servings) 6.3�0.Sweet/salty snack foods (servings) 3.3�0.Total fat (% of energy) 31.0�0.Saturated fat (% of energy) 11.3�0.Protein (% of energy) 14.6�0.Carbohydrate (% of energy) 55.4�0.Calcium (mg) 1,222�41Iron (mg) 15.8�0.Vitamin A (IU) 8,659�33Vitamin C (mg) 152.7�5.Vitamin B-6 (mg) 1.85�0.Folate (�g) 332.8�10Zinc (mg) 12.7�0.
aP values are for transformed variables (except for macronutrients as % of energy andbSE�standard error.x,yDifferent superscripts indicate statistically significant differences using Bonferroni adj
Table 4. Percentage of adolescent girls meeting dietary recommend
Dietaryrecommendation
Fruits �2 servings/dayVegetables (not including french fries) �3 servings/dayc
Vegetables (including french fries) �3 servings/dayGrains �6 servings/dayTotal fat �30% of energy intakeSaturated fat �10% of energy intakeCalcium �1,300 mg/dayIron �15 mg/dayVitamin A �2,330 IU/dayVitamin C �65 mg/dayVitamin B-6 �1.2 mg/dayFolate �400 �g/dayZinc �9 mg/day
aDietary recommendations are Healthy People 2010 Nutrition Objectives for fruits and vbSE�standard error.cThe recommended amount does not exclude french fries; therefore, comparisons shoux,yDifferent superscripts indicate statistically significant differences using Bonferroni adj
nteractions with Ethnicity/Race and Weight Statusn general, ethnicity/race did not confound the relation-hip between dietary intake and weight-control behav-
used in the past year in adolescent boys
Weight-Control Behaviors
P valueaHealthful only(N�798)
Unhealthful(N�650)
™™™™™™™™™™™mean�SE b™™™™™™™™™™™™™™32,238�68 2,289�69 .5662.32�0.08x,y 2.55�0.08y .0021.64�0.07 1.76�0.08 .4011.80�0.08 1.95�0.08 .1146.3�0.2 6.3�0.2 .7252.9�0.2y 3.1�0.2x,y .006
30.3�0.2y 30.0�0.2y .00310.7�0.1y 10.6�0.1y �.00114.9�0.1 14.6�0.1 .05955.9�0.2 56.3�0.3 .054
1,207�38 1,148�39 .10716.0�0.5 15.6�0.6 .253
9,041�303 8,871�318 .361155.3�4.6 162.9�4.9 .1771.87�0.05 1.81�0.05 .349
338.2�10.0 325.0�10.4 .23012.8�0.4 12.3�0.4 .392
intake).
ts.
sa by types of weight-control behaviors
Weight-Control Behaviors
P valueNone(N�253)
Healthful only(N�622)
Unhealthful(N�1,168)
4™™™™™™™™™™™™™™mean�SE b™™™™™™™™™™™™™346.8�3.5x,y 50.5�2.5x 41.2�2.1y �.00116.2�2.5x,y 20.1�1.8x 14.0�1.5y .00317.2�2.6x,y 22.8�1.9y 16.2�1.6x .00145.4�3.3x 40.2�2.4x 34.3�2.0y .00147.2�3.6 48.9�2.6 51.5�2.2 .35631.6�3.7x 40.4�2.8y 45.0�2.5y �.00139.6�3.2x 33.6�2.4x 25.7�2.1y �.00145.7�3.3x 42.5�2.3x 33.4�1.9y .00192.6�1.9 93.1�1.3 89.9�1.0 .04983.9�2.6x 83.1�1.7x,y 77.9�1.3y .01276.4�3.2x 72.7�2.2x 63.0�1.8y �.00129.8�3.0x 30.1�2.1x 22.6�1.8y �.00166.9�3.3x 63.7�2.3x 52.4�1.8y �.001
les and Dietary Reference Intakes for nutrients.
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ors. The only exception was that African-American girlssing healthful weight-control behaviors were more
ikely to meet dietary recommendations for vegetables30.8%) than white girls using healthful weight-controlehaviors (14.2%) (overall P�.007 for 8 df test, post hoc�.009 for 2 df test). In contrast, vegetable intake did notiffer between other African-American and white girls.lthough the P values are small, inferences must beade cautiously because many outcomes were tested for
nteractions with ethnicity/race, and the post hoc testsere not preplanned, but rather were data driven. Over-eight status did not confound any of the relationshipsetween dietary intake and weight-control behavior inither girls or boys.
ISCUSSIONhe current study explored associations between differ-nt types of weight-control behaviors and dietary intakemong adolescent girls and boys. Among adolescent girls,he patterns of association between unhealthful weightehaviors and dietary intake were of greater concernhan among the boys. Girls engaging in unhealthfuleight-control behaviors had lower intakes of fruits, veg-tables, grains, and all of the micronutrients assessed inhis study than girls reporting only healthful weight-ontrol behaviors. As compared with girls not reportingny weight-control behaviors, girls engaging in unhealth-ul weight-control behaviors had lower intakes of most ofhe micronutrients that were examined. Of particularoncern were the low intakes of calcium and iron in girlssing unhealthful weight-control behaviors, because in-ake of these nutrients tends to be less than dietaryecommendations for all adolescent girls, regardless ofheir dieting status (33).
Table 5. Percentage of adolescent boys meeting dietary recommend
Dietaryrecommendation
Fruits �2 servings/dayVegetables (not including french fries) �3 servings/dayc
Vegetables (including french fries) �3 servings/dayGrains �6 servings/dayTotal fat �30% of energy intakeSaturated fat �10% of energy intakeCalcium �1,300 mg/dayIron �11 mg/dayVitamin A �3,000 IU/dayVitamin C �75 mg/dayVitamin B-6 �1.3 mg/dayFolate �400 �g/dayZinc �11 mg/day
aDietary recommendations are Healthy People 2010 Nutrition Objectives for fruits and vbSE�standard error.cThe recommended amount does not exclude french fries; therefore, comparisons shoux,yDifferent superscripts indicate statistically significant differences using Bonferroni adj
In contrast to the girls, boys reporting weight-control g
18 June 2004 Volume 104 Number 6
ehaviors (healthful and unhealthful) did not differreatly from boys not reporting any weight-control behav-ors. Furthermore, the few differences that were found inhe boys suggested an improved dietary intake amongoys trying to control their weight. Sex differences inatterns of association between unhealthful weight-con-rol behaviors and dietary intake found in the currenttudy suggest that the use of unhealthful weight-controlehaviors represents a different set of behaviors (andossibly associated attitudes) for boys than for girls. Fur-her research is needed to better understand motivationsnd behaviors of adolescent boys reporting the use ofealthful and unhealthful weight-control behaviors.Findings from the current study confirm previous find-
ngs regarding sex differences and the importance of dis-inguishing between healthful and unhealthful weight-ontrol behaviors. In a study using data from the Youthisk Behavior Survey, extremely unhealthful weight-ontrol behaviors (defined as vomiting or diet pill use)ere associated with decreased fruit and vegetable in-
ake in girls. In contrast, moderate weight-control behav-ors (defined as all other methods) were associated withncreased fruit and vegetable intake and decreased high-at food intake in both girls and boys (15).
The high prevalence of girls using unhealthful weight-ontrol behaviors (64% of the girls) and the strong asso-iations between these behaviors and inadequate dietaryntake point to a need for education about healthful strat-gies for adolescent girls who are interested in weightanagement. It may be helpful to deter girls from “diet-
ng,” which tends to be short-term, and encourage adop-ion of more healthful behaviors that can be integratednto one’s lifestyle, such as substituting fruits and vege-ables for higher-fat snack foods. Findings from ethno-
sa by types of weight-control behaviors
Weight-Control Behaviors
P valueNone Healthful only Unhealthful
4™™™™™™™™™™™™™™mean�SE b™™™™™™™™™™™™341.8�2.6x 44.6�2.3x,y 48.9�2.5y .04511.4�1.8x 12.9�1.6x,y 16.6�1.7y .02013.9�1.9x 15.1�1.7x,y 18.9�1.8y .03545.6�2.7 42.8�2.4 40.0�2.5 .15141.2�2.0 45.2�1.8 47.8�2.0 .07228.0�2.3x 37.2�2.0y 40.7�2.2y �.00142.0�2.7 40.9�2.5 38.8�2.6 .52567.1�2.8x 67.1�2.6x 59.9�2.7y .00787.8�1.7 88.8�1.5 85.8�1.6 .22977.2�1.8 78.4�1.6 74.9�1.7 .31268.3�2.3 69.7�2.1 64.4�2.2 .10129.9�2.3 32.8�0.2 30.1�2.2 .41954.0�2.9 52.8�2.7 47.5�2.8 .053
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dolescent girls suggests differences between “dieting”nd “watching what I eat.” “Dieting” tended to be associ-ted with poorer dietary intake, whereas “watching” wasctually associated with higher calcium intake. It may bemportant to teach adolescents how to “watch” what theyat, to ensure that if energy intake is reduced, nutrientntake remains stable and adequate. That said, it is im-ortant to note that even the behaviors classified in thisaper as “healthful” may turn into unhealthful behaviorsf done excessively. Thus, any messages promoting these of healthful weight-control behaviors need to be givenith caution.Strengths of the present study include the comprehen-
ive assessments of weight-control behaviors and dietaryntake. Most large population-based studies of youth ad-ress a broader range of adolescent health concerns andhus have only included a few questions about weight-ontrol behaviors and dietary intake (15,16,21). In addi-ion, although the study population was drawn from onlyne Midwestern state, its large and diverse nature inerms of ethnicity and socioeconomic backgrounds pro-ides some confidence in making extrapolations to aroader sector of the adolescent population. However,tudy limitations also need to be considered. Althoughhe time periods referred to in the questions on weight-ontrol behaviors and dietary intake were similar (previ-us year), we cannot be sure that the behaviors wereccurring simultaneously and that dietary intake wasoorer during the exact time period that girls were en-aging in unhealthful weight-control behaviors. Further-ore, we cannot assert that the relationship was causal
nd that the use of unhealthful weight-control behaviorsas leading to poorer dietary intake.
ONCLUSIONSindings from the present study provide justification for
nterventions aimed at preventing unhealthful weight-ontrol behaviors, particularly among adolescent girls.nterventions aimed at preventing unhealthful weight-ontrol behaviors should include both educational andnvironmental components. Educational messages foroth sexes can address the reasons why adolescentsngage in unhealthful weight-control behaviors, theotential dangers and futility of unhealthful dieting,nowledge and skills for the use of healthful weight-ontrol behaviors (when appropriate), and skills for re-isting potentially harmful social influences to engage innhealthful weight-control behaviors (35-37). Interven-ions should also directly address the social environmentsf the adolescent, including proximal factors such aseight-related norms and behaviors of family membersnd peers, and more distal factors, such as messages ineen magazines and other media regarding weight-con-rol strategies, because all of these social sources influ-nce whether and how an adolescent will try to controleight (38,39).Dietitians can play a major role in the prevention of
nhealthful weight-control behaviors through their clin-cal work with adolescents and their families, outreach tochools and community centers, and advocacy work suchs writing teen-friendly magazine articles on nutritionnd weight control. Clearly the messages should focus on
ealthful methods to control weight and yet maintaindequate nutrient intake. Dietitians are in a unique po-ition in that they also have the training and skills to helpdolescents at risk for obesity incorporate healthfuleight-control behaviors into their lifestyle, whether foreight maintenance or gradual weight loss.
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