Objective. To examine the cross-sectional relationships between weight concerns, weight control behaviors, and initiation of tobacco use among youths.
Study Design. Smoking status, weight concerns, and weight control behaviors were assessed in a cross-sectional sample of 16 862 children, 9 to 14 years of age, in 1996. Logistic regression was used to examine the relationship between weight concerns, weight control behaviors, and early stages of smoking initiation (precontemplation, contemplation, and experimentation). All analyses were adjusted for age, body mass index, and known predictors of initiation.
Results. Approximately 9% of participants had experimented with cigarettes, and 6% were contemplating cigarette smoking. Contemplation of tobacco use was associated with misperception of being overweight (boys: odds ratio [OR], 1.65; 95% confidence interval [CI], 1.10–2.48), unhappiness with appearance (girls: OR, 2.05; 95% CI, 1.48–2.84; boys: OR, 1.60; 95% CI, 1.05–2.42), and a tendency to change eating patterns around peers (girls: OR, 2.87; 95% CI, 2.28–3.62; boys: OR, 1.83; 95% CI, 1.25–2.66). Experimentation with cigarettes was associated with daily exercise to control weight among boys (OR, 1.92; 95% CI, 1.07–3.43) and with monthly purging (OR, 2.54; 95% CI, 1.27–5.07) and daily dieting among girls (OR, 1.79; 95% CI, 1.09–2.96).
Conclusions. Our findings suggest that, among both girls and boys, contemplation of smoking is positively related to weight concerns. Experimentation seems to be positively related to weight control behaviors. It is important for both pediatricians and comprehensive school health programs to address healthy methods of weight maintenance and to dispel the notion of tobacco use as a method of weight control.
- BMI =
- body mass index •
- OR =
- odds ratio •
- CI =
- 95% confidence interval
Experimentation with tobacco is still a common rite of passage among American adolescents. Three-quarters of American youths have tried at least a few puffs of a cigarette before age 18,1 and prevalence of current smoking among high-school students increased from 27.5% in 1991 to 36.4% in 1997.2Furthermore, 30% of youths become regular users of this powerfully addictive drug.1 Understanding how adolescents progress through the initial stages of tobacco use and what predicts these transitions will help delineate optimal points for intervention to prevent adolescent smoking.
The onset of tobacco use seems to be a series of stages through which a child progresses from receptivity to experimentation to addiction.1 Based on the transtheoretical model of change that has been used to study adult smoking cessation, Stern et al3 have defined four stages of adolescent smoking initiation. 1) Precontemplation: these adolescents have not yet begun to think of smoking and express no desire to smoke in the future. They are either ignoring social pressures to smoke or have not constructed positive reasons to start smoking. 2) Contemplation: these youngsters are thinking about starting to smoke. They have begun to develop positive attitudes about smoking and are aware of pressures to smoke. Evans et al4 have defined youngsters in this stage as “susceptible.” 3) Action: these adolescents have started experimenting with cigarettes. They are not yet committed to smoking and receive minimal pleasure from it. Pierce et al5 have referred to this stage as “experimentation,” a term we will use throughout this article to refer to any cigarette use that is not yet regular. 4) Maintenance: these children are smoking on a regular basis and express a commitment to smoking both now and in the future. Nicotine dependence is often considered the fifth stage in the model of smoking initiation,1 in which youths demonstrate a physiologic need for nicotine.
Although there are limited data, it seems that each stage of smoking initiation may have a different set of risk factors. Moreover, that set of risk factors may differ by gender.1 For example, parental smoking may positively influence contemplation and experimentation, but does not seem to be related to regular smoking.6 The effect of parental smoking is also more pronounced among girls than boys.1 The influence of peer smoking seems to be greatest at the contemplation and experimentation stages and may be more pronounced among boys than girls.1
To our knowledge, no studies have assessed the association between weight concerns, weight control behaviors, and the earliest stages of smoking initiation. However, previous studies have suggested that weight concerns and dieting behaviors are positively related to adolescent smoking, particularly among females.7–15 Two hypotheses have been proposed to explain this relationship.16 ,17 First, adolescents are susceptible to society's emphasis on slenderness and may initiate smoking as a weight control measure. Many adolescents believe that smoking is an effective weight control method, and girls tend to adhere to this belief more than boys do.11 ,18 Girls also tend to use more extreme methods of weight control than boys do19–21 and are more likely than boys to report smoking for the purpose of weight control.11 ,20 Alternatively, negative health behaviors may cluster during adolescence, and smoking and dieting may be related to a broader tendency to engage in unhealthy behaviors.17Smoking and dieting are both behavioral expressions of rebelliousness, maturity, and independence and may have similar functional meaning for adolescents.17
The present study examines the relationships between weight concerns, weight control behaviors, and stages of smoking initiation among boys and girls 9 to 14 years of age. Because of the young age of our study participants, we focus exclusively on the earliest stages of tobacco use: precontemplation, contemplation, and experimentation. We hypothesize that weight concerns and weight control behaviors are positively related to contemplation and experimentation, independent of age, body mass index (BMI), and peer, family, and tobacco industry influences, and that relationships will be stronger among girls than boys.
Study participants for the Growing Up Today Study were recruited in 1996 by identifying Nurses' Health Study II participants who reported having a least one child between the ages of 9 and 14. We identified 40 968 women who had given birth between 1982 and 1986. We contacted only the 34 174 women who were prompt responders to the most recent Nurses' Health Study questionnaire because continued participation is essential to all cohort studies. We sent letters briefly explaining the goals of the new study and requested permission from the mothers to contact their child/children. Mothers who gave permission provided each child's name, age, gender, and address (if different from the mother's address). Information was provided by 18 526 women for 26 765 children. We invited these children to join the Growing Up Today Study by sending them a packet that included a letter inviting them to participate and a gender-specific questionnaire. Return of a completed questionnaire was considered consent to participate. The study was approved by Human Subjects Committees at the Harvard School of Public Health and Brigham and Women's Hospital.
Mothers who gave us permission to contact their children were slightly less likely to smoke (9% vs 10%) and were leaner (25.4 kg/m2 vs 45.6 kg/m2) than women who did not grant us permission. However, the two groups of mothers were not different in terms of age (39.7 years vs 79.8 years).
Children were asked to report their measured height and weight. Limited data exist on the validity of self-reported heights and weights among preadolescents and adolescents. Childress et al22observed that both weight (Pearson r = 0.97) and height (Pearson r = 0.90) were validly reported among 139 females and 49 males 9 to 16 years of age. Similarly, in a sample of 806 sixth graders, moderately high correlations were found for weight and height in both boys (r = 0.90, r = 0.74) and girls (r = 0.84, r = 0.62).23 In a pilot study that we conducted among 39 girls ages 10 to 17, we did not find a systematic bias in reported weights. Ten percent of the girls who reported their weights underreported and 3% overreported their weight. The correlations between self-reported and measured weight and height were r = 0.98 for weight and r = 0.73 for height. These results suggest that preadolescents and adolescents can reasonably self-report height and weight.
Children were classified as underweight if their BMI (wt [kg]/ht [m]2) was ≤15th percentile for age and sex, according to reference data from NHANES I.24 Overweight children were defined as those having a BMI equal to or >85th percentile for age and sex. The same BMI cutoffs were used for all racial groups.
We also asked children to describe their weight in one of five categories: very underweight, slightly underweight, just about right, slightly overweight, or very overweight. Children who described themselves as slightly or very overweight, but who were not overweight by the above standards, were classified as having a misperception of being overweight. Girls were also asked whether they had started having menstrual periods.
Smoking status was measured with two questions derived from the Youth Risk Behavior Survey25 and the California Tobacco Survey.26 We asked, “Have you ever tried or experimented with cigarette smoking, even a few puffs?” Children who reported they had not experimented were asked, “Do you think you will try a cigarette in the next year?” Response categories were no, maybe, and probably will. Children who reported that they had experimented were asked whether they had smoked in the last month and whether they had smoked more than 100 cigarettes in their lifetime. From these questions, we classified children as precontemplators (reported that they had not experimented with cigarette smoking and will not try a cigarette in the next year), contemplators (reported that they had not tried cigarette smoking but may or probably will try a cigarette in the next year), experimenters (reported that they had tried cigarette smoking), and regular smokers (reported that they had smoked in the last month and had smoked more than 100 cigarettes in their lifetime). We also asked whether anyone in their household smoked, how many of their friends smoked (categorized as most or all versus few, one, or none), whether they had ever bought or been given items with the name of a cigarette on them, and whether they thought they would ever use such items.
Questions on weight concerns were derived from the McKnight Risk Factor Survey,27 a validated self-report instrument for preadolescents and adolescents. We asked children to report how often in the past year they had thought about wanting to be thinner, worried about fat on their bodies, felt fat, or felt happy with their looks. Girls were also asked how often they had worried about gaining 2 pounds, and boys were asked how often they had thought about wanting bigger muscles. Response categories ranged from never to always. From this instrument, we calculated a weight concern score based on children's reported frequencies of these concerns. Children were considered to be overly concerned with their weight if their weight concern score was in the highest quintile for their gender. The test-retest correlation and Cronbach's α for the summary weight concern score derived from this instrument are high (test-retestr = 0.84, Cronbach's 0.86).27
Children were also asked to report how frequently they changed their eating habits around their peers. Response categories ranged from never to always, and we classified children based on their reported frequency of altering their eating patterns (a lot or always versus less than a lot).
Weight Control Behaviors
Questions on weight control methods were adapted from the Youth Risk Behavior Surveillance System questionnaire developed by the Division of Adolescent and School Health at the Centers for Disease Control and Prevention.28 We asked children to report how frequently in the past year they had engaged in the following behaviors to lose weight or to keep from gaining weight: dieting, exercising, using laxatives, and vomiting. Response categories ranged from never to every day. From these questions, we defined purging as the use of laxatives or self-induced vomiting at least once a month to lose or maintain weight. We also classified children based on their reported frequency of dieting or exercising to lose weight (daily versus less than daily).
We also asked children, “During the past year, how often have you eaten so much food in a short period of time that you would be embarrassed if others saw you (binge-eating or gorging)?” Response categories ranged from never to more than once a week. Children who reported that they had engaged in this behavior in the past year were asked, “Did you feel out of control, like you couldn't stop eating even if you wanted to stop?” From these questions, we defined binging as eating an excessive amount of food and reporting an inability to stop eating even when desired (at least monthly versus less than once a month).
The activity portion of the survey was modified slightly from a survey previously validated in children ages 10 to 14.29Children were asked how much time per week during the past year was usually spent participating in each of 16 activities. Response categories ranged from none to more than 6 hours per week. We calculated the total number of hours per week spent in physical activity. Children were classified as highly active if their total hours of activity per week placed them in the top quintile for their gender.
In a pilot study we conducted among 1035 students in grades 6 through 10, the hours of physical activity per week reported on this instrument were reasonably correlated with the time taken to complete a 1-mile run (girls, r = −0.23; boys, r = −0.24). Correlations between activity and fitness were highest when we measured activity as the time spent only in activities that translate into cardiorespiratory conditioning (girls, r = −0.41; boys, r = −0.48).
Questionnaires were sent in 1996 to the 13 261 girls and 13 504 boys whose mothers had granted us consent to invite them to participate in the Growing Up Today Study. Approximately 68% of the girls (n = 9019) and 58% of the boys (n = 7843) returned completed questionnaires, thereby assenting to participate in the cohort. Mothers whose children returned the baseline questionnaire were leaner (25.2 kg/m2 vs 25.7 kg/m2) and younger (39.6 years vs 39.9 years) than mothers whose children did not to return the baseline questionnaire.
Participants were excluded from analysis if they provided no weight and height information (0.7% of girls and 0.8% of boys), no information on smoking status (0.4% of girls and 1.3% of boys), implausible heights or weights for heights (1.4% of girls and 1.1% of boys), or estimates of physical activity that exceeded 40 hours per week (3.4% of girls and 4.9% of boys). The prevalence of experimentation was higher among children excluded from analysis than among those included. The final sample for analysis included 8299 girls and 7067 boys.
Statistical analyses were performed using SAS.30All analyses were stratified by gender. Age- and gender-specificz scores were calculated for BMI. We calculated the prevalence of weight concerns and weight control behaviors by smoking status and gender, adjusted for age, and for age- and gender-specificz scores of BMI. Logistic regression was used to examine the associations among smoking status (the outcome), weight concerns, weight control behaviors, age, age- and gender-specific zscore of BMI, ethnicity, menarcheal status, and known predictors of adolescent tobacco uptake (smokers in the household, friends who smoke, possession of tobacco promotional items, and willingness to use tobacco promotional items). Separate analyses were conducted for each weight concern and weight control behavior.
The sample of 15 366 9- to 14-year-old children was evenly distributed across the age range (Table 1), although there were slightly fewer children in the extreme age groups. There were slightly more girls than boys (54% vs 46%). The sample was approximately 93% white, 1% black, 1.5% Hispanic, and 1.5% Asian.
The distribution of precontemplators, contemplators, and experimenters by age and gender are shown in Table 2. Overall, 784 girls (10%) and 737 boys (10%) had experimented with cigarettes, and 601 girls (7%) and 350 boys (5%) were contemplating smoking. Among those who had experimented, 48 girls (6%) and 40 boys (5%) were regular smokers. Because the number of regular smokers was so small, regular smokers were combined with experimenters in all analyses. The prevalence of contemplators and experimenters increased with age among both boys and girls. Known predictors of adolescent tobacco uptake (smokers in the household, friends who smoke, possession of tobacco promotional items, and willingness to use such items) were positively related to the three stages of smoking initiation (χ2 for trend P ≤ .001).
With each progressive stage of tobacco uptake among girls, prevalence of underweight (BMI ≤15th percentile) decreased, and prevalence of overweight increased (BMI ≥85th percentile; Table 3). Among boys, experimenters were more overweight than contemplators and precontemplators. After adjusting for known predictors of tobacco uptake, weight was associated with stages of tobacco initiation only among boys; experimenters were 40% more likely to be overweight than contemplators (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.04–1.92; Table 4).
The prevalence of weight concerns and weight control behaviors, adjusted for age and for age- and gender-specific z scores of BMI, was higher among girls than boys. The prevalence of weight concerns was higher among contemplators and experimenters than precontemplators among both girls and boys (Table 3). Among girls, ∼15% of contemplators and ∼14% of experimenters misperceived themselves as overweight, compared with 10% of precontemplators. Although the prevalence of misperception of being overweight was lower among boys than girls, the trend across stages of smoking initiation seems similar: among boys, ∼9% of contemplators and ∼7% experimenters misperceived themselves as overweight, compared with 5% of precontemplators. After adjusting for BMI and known predictors of tobacco uptake, misperception of being overweight was significantly associated with contemplation only among boys (OR, 1.65; 95% CI, 1.10–2.48; Table 4). Overconcern with weight was significantly associated with contemplation among girls (OR, 2.23; 95% CI, 1.80–2.77). Among both girls and boys, contemplation was also associated with being unhappy with one's appearance (girls: OR, 2.05; 95% CI, 1.48–2.84; boys: OR, 1.60; 95% CI, 1.05–2.42) and with a tendency to change eating patterns around peers of the opposite sex (girls: OR, 2.87; 95% CI, 2.28–3.62; boys: OR, 1.83; 95% CI, 1.25–2.66; Table 4).
Although the prevalence of weight control measures such as dieting, exercising, and purging was highest in the experimentation stage among both girls and boys (Table 3), in the multivariate model, weight control measures were related to both contemplation and experimentation, and associations between specific measures and stages of initiation differed somewhat by gender. Among girls, binging was positively associated with contemplation (OR, 2.52; 95% CI, 1.53–4.14). Daily dieting and monthly purging were positively associated with experimentation (dieting: OR, 1.79; 95% CI, 1.09–2.96; purging: OR, 2.54; 95% CI, 1.27–5.07). Among boys, daily exercise to lose weight was positively associated with experimentation (OR, 1.92; 95% CI, 1.07–3.43). Purging was not examined among boys because prevalence was too low. Similarly, prevalence of combined binging and purging was too low to study among girls or boys.
Ethnicity was not associated with contemplation or experimentation among girls or boys (data not shown). Associations between stages of initiation, weight concerns, and weight control behaviors were slightly higher when analyses included children who were initially excluded because of implausible heights, weights-for-heights, or estimates of activity; thus, the estimates reported here are conservative and are biased toward the null. Among girls, associations were not materially different when menarche was also included as a covariate.
To our knowledge, this study is the first to demonstrate a relationship between weight concerns, weight control behaviors, and early stages of smoking initiation in a sample of both girls and boys as young as 9 years old. Our data are consistent with other studies in demonstrating that early stages of smoking initiation are also strongly related to the smoking status of friends and household members and a willingness to use tobacco promotional items.26 ,31However, the relationships between weight concerns, weight control behaviors, and stages of smoking initiation have interesting implications that warrant further attention. Independent of age, BMI, and known predictors of tobacco uptake, contemplation of cigarette use was positively related to concern about weight, whereas experimentation with cigarettes was positively related to engaging in weight control behaviors. Although these relationships were seen among both girls and boys, they seem to be stronger among girls. Girls who moved beyond being concerned with their weight to actually engaging in extreme weight control behaviors were more likely to also move beyond thinking about smoking to experimenting with cigarettes. Further follow-up of this cohort will allow us to assess the direction of causality.
The majority of studies assessing the relationship between weight concerns, weight control behaviors, and youth smoking initiation have focused on regular cigarette use among children who are at least 12 years old.8 ,9 ,11 31–36 Although the average age of smoking initiation is 14.5 years,1 our data suggest that children younger than 12 years old are thinking about smoking or have experimented with cigarettes. Given that the early onset of smoking has been shown to be predictive of sustained adolescent and adulthood smoking37 ,38 and that lung cancer mortality is highest among adults who began smoking before age 15,39 it is important to examine predictors of smoking initiation in the preteen years, when youths are becoming receptive to the idea of smoking.
Concern about weight has often been touted as a reason that girls initiate smoking.1 ,16 However, recent data suggest that the relationships between weight concerns, weight control behaviors, and smoking initiation are not as gender-specific as had been believed. In a cross-sectional survey of 34 000 adolescents, frequency of tobacco use was associated with dieting frequency in girls and purging behavior in both boys and girls.9 A prospective study of 1705 7th- to 10th-grade students demonstrated that girls and boys who reported a fear of weight gain or a strong desire to be as thin as possible were more than twice as likely to be smokers at baseline as girls and boys who did not report these concerns.8 A study of tobacco use and unhealthy weight loss behaviors among 539 sixth-grade students revealed that girls who used unhealthy weight loss methods (vomiting or use of laxatives, water pills, or diet pills) were 14 times more likely to smoke than those who did not. Although the magnitude of association was weaker among boys, the relationship remained significant; boys who engaged in unhealthy weight loss methods were 4 times more likely to smoke than those who did not.10 Consistent with these studies, our results suggest that weight concerns and weight control behaviors may be related to the earliest stages of tobacco uptake in both girls and boys.
Strengths of this study include its large sample of children from all over the United States, inclusion of both girls and boys, its diversity of weight concern and weight control questions, inclusion of other predictors of adolescent smoking initiation, and detailed classification of current smoking status. Limitations include the lack of questions specifically related to the use of smoking to control weight and the cross-sectional nature of the study. In addition, the results presented here are based on self-reported information on smoking from children and adolescents. Although we did not validate report of smoking with objective measures in this study, 90% agreement between youth self-report of smoking and cotinine levels has been demonstrated elsewhere.40 Finally, our study population does not represent a random sample of all US adolescents. The cohort is predominately white, reflecting the ethnic composition of the mothers who are participants in the Nurses' Health Study II. Therefore, we may not be able to generalize our results to all races. Because all participants are children of nurses, the possibility of confounding as a result of socioeconomic factors is reduced but not eliminated. In addition, the relatively low prevalence of high-risk behaviors in our study population suggests that the children who completed our questionnaire may be a particularly health-conscious group. However, associations between weight concerns, weight control behaviors, and smoking initiation would most likely not differ between respondents and nonrespondents.
In summary, the relationships between weight concerns, weight control behaviors, and tobacco uptake raise important questions about the factors in our society that drive children to be concerned with their weight and to practice unhealthy weight control behaviors. Given the rising prevalence of obesity among adolescents, strategies to educate children on body image and healthy weight control practices must be developed in such a way as to counteract both tobacco use and obesity. It is important for both pediatricians and comprehensive school health programs to address healthy methods of weight maintenance and to dispel the notion of tobacco use as a method of weight control.
This work was supported by a grant from the Robert Wood Foundation and by Grant DK46834 from the National Institutes of Health.
- Received October 14, 1998.
- Accepted February 22, 1999.
Reprint requests to (A.L.F.) Channing Laboratory, 181 Longwood Ave, Boston, MA 02115. E-mail:
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- ↵Massachusetts Department of Education. Massachusetts 1992 Youth Risk Behavior Survey Results. Quincy, MA: Massachusetts Department of Education; 1993
- ↵Pierce J, Evans N, Farkas A, et al. Tobacco Use in California: An Evaluation of the Tobacco Control Program. La Jolla, CA: University of California, San Diego; 1994
- ↵Peterson K, Field A, Fox M, et al. Validation of the Youth Risk Behavioral Surveillance System (YRBSS) Questions on Dietary Behaviors and Physical Activity Among Adolescents in Grades 9 Through 12. Prepared for the Centers for Disease Control and Prevention, Division of Adolescent and School Health. Boston, MA: Harvard School of Public Health; 1996
- ↵SAS Institute Inc. SAS User's Guide: Statistics. Cary, NC: SAS Institute, Inc; 1991
- ↵US Department of Health and Human Services. Reducing the Health Consequences of Smoking: 25 Years of Progress: A Report of the Surgeon General. Rockville, MD: US Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 1989
- Copyright © 1999 American Academy of Pediatrics