Helaine Rockett

Activity, Dietary Intake, and Weight Changes in a Longitudinal Study of Preadolescent and Adolescent Boys and Girls

Objective. To examine the role of physical activity, inactivity, and dietary patterns on annual weight changes among preadolescents and adolescents, taking growth and development into account. Study Design. We studied a cohort of 6149 girls and 4620 boys from all over the United States who were 9 to 14 years old in 1996. All returned questionnaires in the fall of 1996 and a year later in 1997. Each child provided his or her current height and weight and a detailed assessment of typical past-year dietary intakes, physical activities, and recreational inactivities (TV, videos/VCR, and video/computer games). Methods. Our hypotheses were that physical activity and dietary fiber intake are negatively correlated with annual changes in adiposity and that recreational inactivity (TV/videos/games), caloric intake, and dietary fat intake are positively correlated with annual changes in adiposity. Separately for boys and girls, we performed regression analysis of 1-year change in body mass index (BMI; kg/m2). All hypothesized factors were in the model simultaneously with several adjustment factors. Results. Larger increases in BMI from 1996 to 1997 were among girls who reported higher caloric intakes (.0061 ± .0026 kg/m2 per 100 kcal/day; β ± standard error), less physical activity (−.0284 ± .0142 kg/m2/hour/day) and more time with TV/videos/games (.0372 ± .0106 kg/m2/hour/day) during the year between the 2 BMI assessments. Larger BMI increases were among boys who reported more time with TV/videos/games (.0384 ± .0101) during the year. For both boys and girls, a larger rise in caloric intake from 1996 to 1997 predicted larger BMI increases (girls: .0059 ± .0027 kg/m2 per increase of 100 kcal/day; boys: .0082 ± .0030). No significant associations were noted for energy-adjusted dietary fat or fiber. Conclusions. For both boys and girls, a 1-year increase in BMI was larger in those who reported more time with TV/videos/games during the year between the 2 BMI measurements, and in those who reported that their caloric intakes increased more from 1 year to the next. Larger year-to-year increases in BMI were also seen among girls who reported higher caloric intakes and less physical activity during the year between the 2 BMI measurements. Although the magnitudes of these estimated effects were small, their cumulative effects, year after year during adolescence, would produce substantial gains in body weight. Strategies to prevent excessive caloric intakes, to decrease time with TV/videos/games, and to increase physical activity would be promising as a means to prevent obesity.

Overweight Among Low-Income Preschool Children Associated With the Consumption of Sweet Drinks: Missouri, 1999–2002

Objective. To examine the association between sweet drink consumption and overweight among preschool children. Methods. A retrospective cohort design was used to examine the association between sweet drink consumption and overweight at follow-up among 10904 children who were aged 2 and 3 years and had height, weight, and Harvard Service Food Frequency Questionnaire data collected between January 1999 and December 2001 and height and weight data collected 1 year later. Sweet drinks included vitamin C-containing juices, other juices, fruit drinks, and sodas as listed on the Harvard Service Food Frequency Questionnaire. Logistic regression was used to adjust for age; gender; race/ethnicity; birth weight; and intake of high-fat foods, sweet foods, and total calories. Results were stratified by baseline BMI. Results. Among children who were normal or underweight at baseline (BMI <85th percentile), the association between sweet drink consumption and development of overweight was positive but not statistically significant. Children who were at risk for overweight at baseline (BMI 85th–<95th percentile) and consumed 1 to <2 drinks/day, 2 to <3 drinks/day, and ≥3 drinks/day were, respectively, 2.0 (95% confidence interval [CI]: 1.3–3.2), 2.0 (95% CI: 1.2–3.2), and 1.8 (95% CI: 1.1–2.8) times as likely to become overweight as the referent (<1 drink/day). Children who were overweight at baseline (BMI ≥95th percentile) and consumed 1 to <2 drinks/day, 2 to <3 drinks/day, and ≥3 drinks/day were, respectively, 2.1, 2.2, and 1.8 times as likely to remain overweight as the referent. Conclusions. Reducing sweet drink consumption might be 1 strategy to manage the weight of preschool children. Additional studies are needed to understand the mechanism by which such consumption contributes to overweight.

Association of Consumption of Fried Food Away From Home With Body Mass Index and Diet Quality in Older Children and Adolescents

Objectives. Rates of overweight have increased dramatically among children in the United States. Although an increase in consumption of food prepared away from home has paralleled overweight trends, few data exist relating food prepared away from home to change in BMI in children. The goals of this study were to (1) examine the cross-sectional and longitudinal associations between consumption of fried foods away from home (FFA) and BMI and (2) examine the cross-sectional associations between intake of FFA and several measures of diet quality. Methods. We studied a cohort of 7745 girls and 6610 boys, aged 9 to 14 years, at baseline in 1996. We obtained BMI from self-reported height and weight, measures of diet quality from a food frequency questionnaire, and weekly servings of FFA during the previous year. We performed linear regression analyses to assess the longitudinal associations between change in consumption of FFA on change in BMI, using data from three 1-year periods from 1996 through 1999. We also related consumption of FFA with intake of selected foods and nutrients at baseline. Results. In cross-sectional analyses, adjusting for potential confounders, mean (SE) BMI was 19.1 (0.13) among children who ate FFA “never or <1/week,” 19.2 (0.13) among those who responded “1 to 3 times/week,” and 19.3 (0.18) among those who responded “4 to 7 times/week.” In longitudinal multivariate models, increasing (over 1 year) consumption of FFA “never or <1/week” to “4 to 7/week” was associated with increasing BMI (β = 0.21 kg/m2; 95% confidence interval: 0.03–0.39) compared with those with low consumption of FFA at baseline and 1 year later. At baseline, frequency of eating FFA was associated with greater intakes of total energy, sugar-sweetened beverages, and trans fat, as well as lower consumption of low-fat dairy foods and fruits and vegetables. Conclusions. These data suggest that older children who consume greater quantities of FFA are heavier, have greater total energy intakes, and have poorer diet quality. Furthermore, increasing consumption of FFA over time may lead to excess weight gain.

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, 9–14 y 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 9–14 y 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.

Validation of a food frequency questionnaire in Native American and Caucasian children 1 to 5 years of age.

Objective: To assess the validity of the Harvard Service Food Frequency Questionnaire (HFFQ) in the diet assessment of Native American and Caucasian children 1 to 5 years of age participating in the North Dakota WIC program. Methods: The 84-item HFFQ was administered twice to the parent or guardian of 131 Native American and 102 Caucasian children ages 1 to 5 years (total n = 233), first at the childs routine WIC visit and then following the completion of three 24-hr dietary recalls taken over approximately 1 month. Average nutrient intakes from the three 24-hr dietary recalls were compared to average nutrient intakes from the HFFQs by calculating Pearson correlation coefficients and adjusting for energy intake and within person variation. Results: Correlation coefficients ranged from 0.26 for dietary fiber to 0.63 for magnesium. The average correlation was 0.52, similar to that found in validation studies among adolescents and adults. The following nutrients had correlations of 0.50 or greater: carbohydrate, sucrose, total fat, vitamin C, vitamin E, vitamin Bl, vitamin B2, niacin, folate, vitamin B6, calcium, magnesium, and iron. Conclusions: The HFFQ is a simple self-administered questionnaire completed by the childs parent or guardian and is useful in assessing the diets of Native American and Caucasian children. It may also provide important nutritional information about this age group for future program planning, research, education, and intervention purposes.

Dairy Consumption and Female Height Growth: Prospective Cohort Study

Background: Because of its nutrients and anabolic hormones, cows milk may promote height growth, which in turn has been related to breast cancer risk. We prospectively investigated associations between dairy intakes and height growth. Methods: A cohort of 5,101 girls from throughout the United States completed annual surveys (1996-2001, 2003), providing height, weight, and past-year diet. At baseline, all were premenarchal, ages 9 years and above, with no serious medical conditions. We studied three outcomes: annual height growth, peak growth velocity, and adult height. Multivariate models estimated the effects of milk, cheese, yogurt, and energy on subsequent growth, adjusted for race/ethnicity, age, prior height, and body mass index. Other models studied fats and proteins. Results: Premenarchal girls who drank >3 servings per day of milk grew 0.11 in. (P = 0.02) more the following year than girls consuming <1 serving per day. Yogurt (+0.13 in./cup; P = 0.02), but not cheese or total calories, predicted height growth. In a separate model, dairy protein (+0.034 in./10 g; P < 0.001) predicted height growth. Larger peak velocities were seen among girls reporting, at baseline, more milk (>3 glasses per day versus <1; +0.14 in., P = 0.01), more yogurt (+0.17 in./cup, P = 0.02), and, in a separate model, more dairy protein (+0.039 in./10 g; P = 0.003). Baseline milk and dairy protein predicted taller adults. Dairy protein was more important than dairy fat, for all outcomes. Nondairy animal protein and vegetable protein were never significant, nor were nondairy animal fat and vegetable fat. Conclusion: Of the foods/nutrients studied, dairy protein had the strongest association with height growth. These findings suggest that a factor in the nonlipid phase of milk, but not protein itself, has growth-promoting action in girls. (Cancer Epidemiol Biomarkers Prev 2009;18(6):1881–7)

Weight Gain in Older Adolescent Females: The Internet, Sleep, Coffee, and Alcohol

OBJECTIVES To examine whether excessive recreational Internet time, insufficient sleep, regular coffee consumption, or alcoholic beverages promote weight gain. STUDY DESIGN A longitudinal cohort of >5000 girls (Growing Up Today Study), from all over the United States and aged 14 to 21 years, returned surveys in 2001 reporting typical past-year recreational Internet time, sleep, coffee (with caffeine), and alcohol consumption. We estimated correlations among these 4 exposures. Each girl also reported her height and weight in 2000 and again in 2001. Multivariate models investigated associations between 1-year change in body mass index and same-year exposures, adjusted for adolescent growth/development, activity, and inactivity. RESULTS The exposures were highly (P < .0001) correlated with each other, except for coffee with Internet time (P > .50). More Internet time, more alcohol, and less sleep were all associated (P < .05) with same-year increases in body mass index. Females, aged 18+ years, who slept <or=5 hours/night (P < .01) or who consumed alcohol 2+servings/week (P < .07) gained more body mass index from 2000 to 2001. For females in weight-promoting categories of all exposures, this translates to nearly 4 extra pounds gained over 1 year. We found no evidence that drinking coffee promotes weight gain. CONCLUSIONS Older girls may benefit from replacing recreational Internet time with sleep and by avoiding alcohol.

Use of a food frequency questionnaire in American Indian and Caucasian pregnant women: a validation study.

BackgroundFood frequency questionnaires (FFQs) have been validated in pregnant women, but few studies have focused specifically on low-income women and minorities. The purpose of this study was to examine the validity of the Harvard Service FFQ (HSFFQ) among low-income American Indian and Caucasian pregnant women.MethodsThe 100-item HSFFQ was administered three times to a sample of pregnant women, and two sets of 24-hour recalls (six total) were collected at approximately 12 and 28 weeks of gestation. The sample included a total of 283 pregnant women who completed Phase 1 of the study and 246 women who completed Phase 2 of the study. Deattenuated Pearson correlation coefficients were used to compare intakes of 24 nutrients estimated from the second and third FFQ to average intakes estimated from the week-12 and week-28 sets of diet recalls.ResultsDeattenuated correlations ranged from 0.09 (polyunsaturated fat) to 0.67 (calcium) for Phase 1 and from 0.27 (sucrose) to 0.63 (total fat) for Phase 2. Average deattenuated correlations for the two phases were 0.48 and 0.47, similar to those reported among other groups of pregnant women.ConclusionThe HSFFQ is a simple self-administered questionnaire that is useful in classifying low-income American Indian and Caucasian women according to relative dietary intake during pregnancy. Its use as a research tool in this population may provide important information about associations of nutrient intakes with pregnancy outcomes and may help to identify groups of women who would benefit most from nutritional interventions.

Breast-feeding and Overweight in Adolescence: Within-family analysis

Background: Previous reports have found associations between having been breast-fed and a reduced risk of being overweight. These associations may be confounded by sociocultural determinants of both breast-feeding and obesity. We addressed this possibility by assessing the association of breast-feeding duration with adolescent obesity within sibling sets. Methods: We surveyed 5614 siblings age 9 to 14 years and their mothers. These children were a subset of participants in the Growing Up Today Study, in which we had previously reported an inverse association of breast-feeding duration with overweight. We compared the prevalence of overweight (body mass index exceeding the age-sex-specific 85th percentile) in siblings who were breast-fed longer than the mean duration of their sibship with those who were breast-fed for a shorter period. Then we compared odds ratios from this within-family analysis with odds ratios from an overall (ie, not within-family) analysis. Results: Mean ± standard deviation breast-feeding duration was 6.4 ± 4.0 months, and crude prevalence of overweight was 19%. On average, siblings who were breast-fed longer than their family mean had breast-feeding duration 3.7 months longer than their shorter-duration siblings. The adjusted odds ratio (OR) for overweight among siblings with longer breast-feeding duration, compared with shorter duration, was 0.92 (95% confidence interval = 0.76-1.11). In overall analyses, the adjusted OR was 0.94 (0.88-1.00) for each 3.7-month increment in breast-feeding duration. Conclusion: The estimated OR for the within-family analysis was close to the overall estimate, suggesting that the apparent protective effect of breast-feeding on later obesity was not highly confounded by unmeasured sociocultural factors. A larger study of siblings, however, would be needed to confirm this conclusion.