Alison E. Field

Longitudinal study of skipping breakfast and weight change in adolescents

BACKGROUND: Several cross-sectional studies reported that heavier children eat breakfast less often. However, no longitudinal studies have addressed whether skipping breakfast leads to excessive weight gain.OBJECTIVE: To investigate whether skipping breakfast was prospectively associated with changes in body fatness.METHODS: A cohort of >14u2009000 boys and girls from all over the US, 9- to 14-y-old in 1996, returned annual mailed questionnaires (1996–1999) for the Growing Up Today Study. We analyzed change in body mass index (BMI; kg/m2) over three 1-y periods among children who reported breakfast frequency.RESULTS: Children who reported that they never eat breakfast had lower energy intakes than those who eat breakfast nearly every day. Children who were more physically active reported higher energy intakes, as did those who reported more time watching television/videos and playing videogames. Like previous studies, skipping breakfast was associated with overweight, cross-sectionally. However, overweight children who never ate breakfast lost BMI over the following year compared to overweight children who ate breakfast nearly every day (boys: −0.66u2009kg/m2 (s.e.=0.22); girls: −0.50u2009kg/m2 (s.e.=0.14)). But normal weight children who never ate breakfast gained weight relative to peers who ate breakfast nearly every day (boys: +0.21u2009kg/m2 (s.e.=0.13); girls: +0.08u2009kg/m2 (s.e.=0.05)). Breakfast frequency was positively correlated with self-reported quality of schoolwork.CONCLUSIONS: Overweight children who never eat breakfast may lose body fat, but normal weight children do not. Since numerous studies link skipping breakfast to poorer academics, children should be encouraged to eat breakfast.

Snack food intake does not predict weight change among children and adolescents

OBJECTIVE: To assess whether intake of snack foods was associated with weight change among children and adolescents.METHODS: Prospective study of 8203 girls and 6774 boys, 9–14u2009y of age in 1996, in an ongoing cohort study who completed at least two questionnaires between 1996 and 1999. Intake of snack foods was assessed in 1996–1998 with a validated food frequency questionnaire designed specifically for children and adolescents. The outcome measure was change in age- and gender-specific z-score of body mass index (BMI).RESULTS: Boys consumed more snack foods than girls during the entire study period. After controlling for Tanner stage of development, age, height change, activity, and inactivity, there was no relation between intake of snack foods and subsequent changes in BMI z-score among the boys (β=−0.004), but snack foods had a weak inverse association (β=−0.007, P<0.05) with weight change among the girls. However, the results were confounded by dieting status, which had a significant positive independent association with BMI change. After controlling for dieting status and whether the mother was overweight, the association between servings per day of snack foods and subsequent changes in BMI z-score were not significant in either gender.DISCUSSION: Our results suggest that although snack foods may have low nutritional value, they were not an important independent determinant of weight gain among children and adolescents.

Association between fruit and vegetable intake and change in body mass index among a large sample of children and adolescents in the United States.

OBJECTIVE: To assess whether intake of fruits and vegetables was associated with change in body mass index (BMI) among a large sample of children and adolescents in the United States.DESIGN: Prospective cohort study of children and adolescent who were 9–14u2009y of age in 1996, when the study began.SUBJECTS: The subjects included 8203 girls and 6715 boys in an ongoing cohort study who completed at least two questionnaires between 1996 and 1999.MEASUREMENTS: Fruit and vegetable intake was assessed in 1996–1998 with a validated food frequency questionnaire designed specifically for children and adolescents. The outcome measure was change in age- and gender-specific z-score of BMI (kg/m2). Self-reported weight and height, which were used to calculate BMI, were collected annually from 1996 to 1999.RESULTS: During 3 years of follow-up, annual changes in BMI were slightly greater among the boys than the girls. After controlling for Tanner stage of development, age, height change, activity and inactivity, which are known or suspected predictors of change in BMI, among the girls there was no relation between intake of fruits, fruit juice, or vegetables (alone or combined) and subsequent changes in BMI z-score. Among the boys, intake of fruit and fruit juice was not predictive of changes in BMI, however, vegetables intake was inversely related to changes in BMI z-score (β per serving=−0.003). However, after adjusting for caloric intake, the magnitude of the effect was diminished and no longer significant.CONCLUSION: Our results suggest that the recommendation for consumption of fruits and vegetables may be well founded, but should not be based on a beneficial effect on weight regulation.

Exposure to the Mass Media, Body Shape Concerns, and Use of Supplements to Improve Weight and Shape Among Male and Female Adolescents

Objective. To assess the prevalence and correlates of products used to improve weight and shape among male and female adolescents. Methods. A cross-sectional study was conducted of 6212 girls and 4237 boys who were 12 to 18 years of age and enrolled in the ongoing Growing Up Today Study. The outcome measure was at least weekly use of any of the following products to improve appearance, muscle mass, or strength: protein powder or shakes, creatine, amino acids/hydroxy methylbutyrate (HMB), dehydroepiandrosterone, growth hormone, or anabolic/injectable steroids. Results. Approximately 4.7% of the boys and 1.6% of the girls used protein powder or shakes, creatine, amino acids/HMB, dehydroepiandrosterone, growth hormone, or anabolic/injectable steroids at least weekly to improve appearance or strength. In multivariate models, boys and girls who thought a lot about wanting more defined muscles (boys: odds ratio [OR]: 1.6; 95% confidence interval [CI]: 1.1–2.2; girls: OR: 2.3; 95% CI: 1.2–3.2) or were trying to gain weight (boys: OR: 3.0; 95% CI: 2.0–4.6; girls: OR: 4.3; 95% CI: 1.6–11.4) were more likely than their peers to use these products. In addition, boys who read men’s, fashion, or health/fitness magazines (OR: 2.3; 95% CI: 1.1–4.9) and girls who were trying to look like women in the media (OR: 2.9; 95% CI: 1.4–4.0) were significantly more likely than their peers to use products to improve appearance or strength, but hours per week watching television, watching sports on television, and participation in team sports were not independently associated with using products to improve appearance or muscle mass. Conclusions. Girls and boys who frequently thought about wanting toned or well-defined muscles were at increased risk for using potentially unhealthful products to enhance their physique. These results suggest that just as girls may resort to unhealthful means to achieve a low body weight, girls and boys may also resort to unhealthful means to achieve other desired physiques.

Weight Concerns, Weight Control Behaviors, and Smoking Initiation

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 16u2009862 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.

Longitudinal relationship between television viewing and leisure-time physical activity during adolescence.

OBJECTIVE. The goal was to examine the longitudinal associations of changes in television viewing and other sources of sedentary behavior with changes in leisure-time moderate/vigorous physical activity in adolescence. METHODS. We studied a cohort of 6369 girls and 4487 boys who were 10 to 15 years of age in 1997. During each of 4 years of follow-up assessments, participants self-reported their weekly hours of television viewing. By using a seasonal questionnaire, we also obtained detailed information on physical activities over the previous year, from which we calculated total leisure-time moderate/vigorous physical activity. We performed linear regression analyses to assess the longitudinal associations between 1-year changes in television viewing and 1-year changes in leisure-time moderate/vigorous physical activity during the same year, using data from 1997 through 2001. RESULTS. One-year changes (mean ± SD) were −0.13 ± 7.2 hours/week for leisure-time moderate/vigorous physical activity, −0.55 ± 7.0 hours/week for television viewing, and −1.02 ± 11.0 hours/week for total sedentary behaviors. In longitudinal models adjusted for age, age2, gender, race/ethnicity, Tanner stage, menarche (in girls), baseline physical activity, and baseline television viewing, we found no substantive relationship between year-to-year changes in television viewing and changes in leisure-time moderate/vigorous physical activity (0.03 hours/week, for each 1-hour/week change in television viewing). There were no material associations in age or gender subgroups. CONCLUSIONS. In this longitudinal study, changes in television viewing were not associated with changes in leisure-time moderate/vigorous physical activity. Our findings suggest that television viewing and leisure-time physical activity are separate constructs, not functional opposites.

Association of weight change, weight control practices, and weight cycling among women in the Nurses' Health Study II.

OBJECTIVE: To assess the association of weight cycling with weight change, weight control practices, and bulimic behaviors.METHODS: A nested study of 2476 young and middle-aged women in the Nurses Health Study II who provided information on intentional weight losses between 1989 and 1993.SAMPLE: In total, 224 women who were severe cyclers, 741 women who were mild cyclers, 967 age- and BMI-matched controls (noncyclers), and 544 women who did not weight cycle and maintained their weight between 1989 and 1993 completed a questionnaire in 2000–2001 assessing recent intentional weight losses, weight control practices, and weight concerns.RESULTS: After controlling for age and body mass index (BMI) in 1993, when weight cycling was initially assessed, mild cyclers gained an average of 6.7 pounds (lbs) more and severe cyclers gained approximately 10.3u2009lbs more than noncyclers between 1993 and 2001. Weight cyclers preferred to change their diet rather than to exercise to control their weight. Severe weight cyclers were less likely than noncyclers to use frequent exercise as a weight control strategy (odds ratio [OR]=0.8, 95% confidence interval (CI) 0.6–1.1). Cyclers were also more likely than noncyclers to engage in binge eating (mild cyclers: OR=1.8, 95% CI 1.4–2.4; and severe cyclers: OR=2.5, 95% CI 1.7–3.5). Independent of weight cycling status, age, and BMI, women who engaged in binge eating gained approximately 5u2009lbs more than their peers (P<0.001).CONCLUSIONS: Weight cycling was associated with greater weight gain, less physical activity, and a higher prevalence of binge eating. Low levels of activity and binge eating may be partially responsible for the large amount of weight regained by weight cyclers.