Issa Zakeri

Eating Patterns and Obesity in Children The Bogalusa Heart Study

BACKGROUND Childhood obesity is a growing public health problem. This study examined the association between eating patterns and overweight status in children who participated in the Bogalusa Heart Study. METHODS A single 24-hour dietary recall was collected on a cross-sectional sample of 1562 children aged 10 years (65% Euro-American [EA], 35% African American [AA]) over a 21-year period. Overweight was defined as body mass index greater than the 85th percentile using Centers for Disease Control and Prevention reference standards. Multivariate logistic regression was used to investigate the association between eating patterns and overweight. RESULTS Consumption of sweetened beverages (58% soft drinks, 20% fruit flavor drinks, 19% tea, and 3% coffee) (p<0.001); sweets (desserts, candy, and sweetened beverages) (p<0.001); meats (mixed meats, poultry, seafood, eggs, pork, and beef) (p<0.051); and total consumption of low-quality foods (p<0.01) were positively associated with overweight status. Total amount of food consumed, specifically from snacks, was positively associated with overweight status (p<0.05). There was a lack of congruency in the types of eating patterns associated with overweight status across four ethnic-gender groups. The percent variance explained from the eating pattern-overweight models was very small. The interaction of ethnicity and gender was significantly associated with overweight status (p<0.001). The odds of being overweight for EA males were 1.2 times higher than for AA females. CONCLUSIONS These results demonstrate that numerous eating patterns were associated with overweight status, yet the odds of being overweight were very small. Additional studies are needed to confirm these findings in a longitudinal sample having multiple days of assessment.

Squire's Quest! Dietary Outcome Evaluation of a Multimedia Game

BACKGROUND Fruit, juice, and vegetable (FJV) consumption among children is low. Innovative programs are needed to enable children to increase FJV intake. Psychoeducational multimedia permits the delivery of interventions as designed and capitalizes on known behavior change principles. DESIGN Elementary school was the unit of recruitment, assignment, and analysis. Twenty-six elementary schools were pair matched on size and percentage of free or reduced-price lunch, and randomly assigned to treatment or control groups. Data were collected just before and just after the program. SETTING/PARTICIPANTS All fourth-grade students in participating elementary schools were invited to participate. Data were collected on 1578 students. MAIN OUTCOME Servings of fruit, 100% juice, and vegetables consumed. INTERVENTION Squires Quest! is a ten-session, psychoeducational, multimedia game delivered over 5 weeks, with each session lasting about 25 minutes. Based on social cognitive theory, educational activities attempted to increase preferences for FJV through multiple exposures and associating fun with their consumption, increase asking behaviors for FJV at home and while eating out, and increase skills in FJV preparation through making virtual recipes. MEASURES Four days of dietary intake were assessed before and after the intervention. Assessment was made by the Food Intake Recording Software System (FIRSSt), which conducts a multiple pass, 24-hour dietary intake interview directly with the children. RESULTS Children participating in Squires Quest! increased their FJV consumption by 1.0 servings more than the children not receiving the program. CONCLUSIONS Psychoeducational multimedia games have the potential to substantially change dietary behavior. More research is warranted.

Relative Reliability and Validity of the Block Kids Questionnaire among Youth Aged 10 to 17 Years

This cross-sectional study tested the reliability and validity of the Block Kids Questionnaire to assess diet during the past 7 days. Within a 7-day period, 10- to 17-year-old children and adolescents completed two 24-hour dietary recalls by telephone, followed by the Block Kids Questionnaire at the end of the week. Test-retest reliability was assessed using intraclass correlations for 18 participants who completed a second Block Kids Questionnaire 1 month later. Validity of the Block Kids Questionnaire compared to the 24-hour dietary recall was assessed for the whole sample and by age group using paired t tests and Pearson correlation coefficients adjusted for attenuation and energy intake. Participants were 83 children and adolescents (57% Hispanic, 21% African-American, and 23% white; 53% were female subjects, mean age 13 years). The Block Kids Questionnaire mean daily consumption values were higher for percent energy from carbohydrate, and servings of fruit, 100% fruit juice, and vegetables, and lower for all other categories compared to the 24-hour dietary recall. All reliability intraclass correlations were >0.30, except percent energy from protein and fruit/vegetable servings. Significant differences in the means between the two dietary assessment methods were noted for most nutrients/food groups. The adjusted correlation coefficients ranged from 0.69 for percent energy from carbohydrate to -0.03 for grain servings, with 60% of the food group servings <0.18. Overall, the majority of the correlation coefficients for children aged >12 years were higher than those aged < or =12 years. These results suggest that the Block Kids Questionnaire has validity for some nutrients, but not most food groups assessed, and appears more useful for adolescents.

Improvements in Middle School Student Dietary Intake After Implementation of the Texas Public School Nutrition Policy

OBJECTIVES We assessed the effect of the Texas Public School Nutrition Policy on middle school student lunchtime food consumption. METHODS Three years of lunch food records were collected from middle school students in southeast Texas: baseline (2001-2002), after local district changes (2002-2003), and 1 year after implementation of the Texas Public School Nutrition Policy (2005-2006). Students recorded amount and source of foods and beverages they consumed. Analysis of variance and covariance and nonparametric tests were used to compare intake after the policy change with intake during the 2 previous years. RESULTS After implementation of the nutrition policy, student lunch consumption of vegetables, milk, and several nutrients increased (protein, fiber, vitamins A and C, calcium, and sodium), and consumption of less desirable items (sweetened beverages, snack chips) decreased, as did percentage of energy from fat. Most of the desired nutrients and foods (vegetables and milk) were obtained from the National School Lunch Program meal. Fewer sweetened beverages, candy, chips, and dessert foods were purchased and consumed, but more of these items were brought from home and purchased from the snack bar. CONCLUSIONS Overall, state school nutrition policies can improve the healthfulness of foods consumed by students at lunch.

Pedometer reliability, validity and daily activity targets among 10- to 15-year-old boys

Abstract The aims of this study were to: (1) determine whether the number of pedometer counts recorded by adolescents differs according to the adiposity of the participant or location on the body; (2) assess the accuracy and reliability of pedometers during field activity; and (3) set adolescent pedometer-based physical activity targets. Seventy-eight 11- to 15-year-old Boy Scouts completed three types of activity: walking, fast walking and running. Each type was performed twice. Participants wore three pedometers and one activity monitor during all activities. Participants were divided into groups of normal weight (BMI < 85th percentile) and at risk of being overweight (BMI ⩾ 85th percentile). Intra-class correlations across the three activities indicated reliability (r = 0.51 – 0.92, P < 0.001). This conclusion was supported by narrow limits of agreement that were within a pre-set range that was practically meaningful. Multivariate analysis of covariance indicated adiposity group differences, but this difference was a function of the increased stature among the larger participants (P < 0.001). Ordinary least-squares regression models and multi-level regression models showed positive associations between the number of pedometer and activity monitor counts recorded by the three groups of participants during all activities (all P < 0.001). The mean number of counts recorded for all participants during the fast walk was 127 counts per minute. In conclusion, the pedometers provided an accurate assessment of adolescent physical activity, and a conservative estimate of 8000 pedometer counts in 60 min is equivalent to 60 min of moderate to vigorous physical activity.

Exploring changes in middle-school student lunch consumption after local school food service policy modifications.

OBJECTIVE This study assessed the impact of changes in school food policy on student lunch consumption in middle schools. METHODS Two years of lunch food records were collected from students at three middle schools in the Houston, Texas area. During the first year, no changes occurred in the school food environment. After that school year was completed, chips and dessert foods were removed from the snack bars of all schools by the Food Service Director. Students recorded the amount and source of food and beverage items consumed. Point-of-service purchase machines provided a day-by-day electronic data file with food and beverage purchases from the snack bars during the 2-year period. Independent t-tests and time series analyses were used to document the impact of the policy change on consumption and sales data between the two years. RESULTS In general, student consumption of sweetened beverages declined and milk, calcium, vitamin A, saturated fat and sodium increased after the policy change. Snack chips consumption from the snack bar declined in year 2; however, consumption of snack chips and candy from vending increased and the number of vending machines in study schools doubled during the study period. Ice cream sales increased significantly in year 2. CONCLUSIONS Policy changes on foods sold in schools can result in changes in student consumption from the targeted environments. However, if all environments do not make similar changes, compensation may occur.

Food, fun, and fitness internet program for girls: pilot evaluation of an e-Health youth obesity prevention program examining predictors of obesity.

OBJECTIVE This pilot study tested whether an Internet-based intervention could achieve change in fruit, juice, and vegetable consumption, physical activity, and self-efficacy in youth at-risk of obesity. METHOD Participants were 80 8-to-10-year-old African American girls at-risk of obesity, with a home computer, Internet access, and an e-mail address. A two-group design was followed. Groups differed only on incentive schedule (immediate, delayed). The 8-week home-based program, conducted entirely over the Internet, promoted fruit, juice, vegetables, and water intake and physical activity. Pre-post measures were collected through self-report via the program website. The study was conducted in the greater Houston, TX, area September through November, 2004. RESULTS Statistically significant pre-to-post differences were observed in fruit, juice, and vegetable consumption (p=.002), physical activity--yesterday (p<.001), physical activity--usually (p=.001), and fruit, juice, and vegetable self-efficacy (p=.003). CONCLUSION Internet-based obesity prevention programs may be an effective channel for promoting healthy diet and physical activity behaviors to youth at-risk of obesity. Additional research is needed to more fully examine their effectiveness at promoting and maintaining diet and physical activity change.

Validation of Cross-Sectional Time Series and Multivariate Adaptive Regression Splines Models for the Prediction of Energy Expenditure in Children and Adolescents Using Doubly Labeled Water

Accurate, nonintrusive, and inexpensive techniques are needed to measure energy expenditure (EE) in free-living populations. Our primary aim in this study was to validate cross-sectional time series (CSTS) and multivariate adaptive regression splines (MARS) models based on observable participant characteristics, heart rate (HR), and accelerometer counts (AC) for prediction of minute-by-minute EE, and hence 24-h total EE (TEE), against a 7-d doubly labeled water (DLW) method in children and adolescents. Our secondary aim was to demonstrate the utility of CSTS and MARS to predict awake EE, sleep EE, and activity EE (AEE) from 7-d HR and AC records, because these shorter periods are not verifiable by DLW, which provides an estimate of the individuals mean TEE over a 7-d interval. CSTS and MARS models were validated in 60 normal-weight and overweight participants (ages 5-18 y). The Actiheart monitor was used to simultaneously measure HR and AC. For prediction of TEE, mean absolute errors were 10.7 +/- 307 kcal/d and 18.7 +/- 252 kcal/d for CSTS and MARS models, respectively, relative to DLW. Corresponding root mean square error values were 305 and 251 kcal/d for CSTS and MARS models, respectively. Bland-Altman plots indicated that the predicted values were in good agreement with the DLW-derived TEE values. Validation of CSTS and MARS models based on participant characteristics, HR monitoring, and accelerometry for the prediction of minute-by-minute EE, and hence 24-h TEE, against the DLW method indicated no systematic bias and acceptable limits of agreement for pediatric groups and individuals under free-living conditions.

Decision boundaries and receiver operating characteristic curves: New methods for determining accelerometer cutpoints

Abstract We propose and evaluate the utility of an alternative method (decision boundaries) for establishing physical activity intensity-related accelerometer cutpoints. Accelerometer data collected from seventy-six 11- to 14-year-old boys during controlled bouts of moderate- and vigorous-intensity field physical activities were assessed. Mean values and standard deviations for moderate- and vigorous-intensity activities were obtained and normal equivalents generated. The decision boundary (the point of intersection of overlapping distributions) was used to create a lower-bound vigorous-intensity cutpoint. Receiver operating characteristic (ROC) curves compared the sensitivity and specificity of the new cutpoint and mean values with the actual activity. There was a 96.5% probability that participants performing vigorous-intensity physical activity were accurately classified when using the decision boundary of 6700 counts per minute, in contrast to the 50% accurately classified when the mean value was used. Inspection of the empirical ROC curve indicated that the decision boundary provided the optimal threshold to distinguish between moderate and vigorous physical activity for this dataset. In conclusion, decision boundaries reduced the error associated with determining accelerometer threshold values. Applying these methods to accelerometer data collected in specific populations will improve the precision with which accelerometer thresholds can be identified.

Application of cross-sectional time series modeling for the prediction of energy expenditure from heart rate and accelerometry

Accurate estimation of energy expenditure (EE) in children and adolescents is required for a better understanding of physiological, behavioral, and environmental factors affecting energy balance. Cross-sectional time series (CSTS) models, which account for correlation structure of repeated observations on the same individual, may be advantageous for prediction of EE. CSTS models for prediction of minute-by-minute EE and, hence, total EE (TEE) from heart rate (HR), physical activity (PA) measured by accelerometry, and observable subject variables were developed in 109 children and adolescents by use of Actiheart and 24-h room respiration calorimetry. CSTS models based on HR, PA, time-invariant covariates, and interactions were developed. These dynamic models involve lagged and lead values of HR and lagged values of PA for better description of the series of minute-by-minute EE. CSTS models with random intercepts and random slopes were investigated. For comparison, likelihood ratio tests were used. Log likelihood increased substantially when random slopes for HR and PA were added. The population-specific model uses HR and 1- and 2-min lagged and lead values of HR, HR(2), and PA and 1- and 2-min lagged values of PA, PA(2), age, age(2), sex, weight, height, minimum HR, sitting HR, HR x height, HR x weight, HR x age, PA x weight, and PA x sex interactions (P < 0.001). Prediction error for TEE was 0.9 +/- 10.3% (mean +/- SD). Errors were not correlated with age, weight, height, or body mass index. CSTS modeling provides a useful predictive model for EE and, hence, TEE in children and adolescents on the basis of HR and PA and other observable explanatory subject characteristics of age, sex, weight, and height.