Senior Research Scientist, Medicine - Stanford Prevention Research Center
Evidence from laboratory and field studies indicates that large portions lead to greater food and energy intake relative to small portions. However, most children and adults demonstrate limited abilities to estimate and control the amounts of food they serve and consume. Five potential environmental strategies appear promising for improving portion control in children: (1) using tall, thin, and small volume glasses and mugs, (2) using smaller diameter and volume plates, bowls and serving utensils, (3) using plates with rims, (4) reducing total television and other screen watching and (5) reducing or eliminating eating while watching television and/or other screens. Further experimental research in real world settings is needed to test these interventions as strategies for portion control and their roles in prevention and treatment of obesity.
View details for DOI 10.1016/j.appet.2014.12.001
View details for Web of Science ID 000352043900006
The Delboeuf Illusion affects perceptions of the relative sizes of concentric shapes. This study was designed to extend research on the application of the Delboeuf illusion to food on a plate by testing whether a plate's rim width and coloring influence perceptual bias to affect perceived food portion size.Within-subjects experimental design. Experiment 1 tested the effect of rim width on perceived food portion size. Experiment 2 tested the effect of rim coloring on perceived food portion size. In both experiments, participants observed a series of photographic images of paired, side-by-side plates varying in designs and amounts of food. From each pair, participants were asked to select the plate that contained more food. Multilevel logistic regression examined the effects of rim width and coloring on perceived food portion size.Experiment 1: participants overestimated the diameter of food portions by 5% and the visual area of food portions by 10% on plates with wider rims compared with plates with very thin rims (P<0.0001). The effect of rim width was greater with larger food portion sizes. Experiment 2: participants overestimated the diameter of food portions by 1.5% and the visual area of food portions by 3% on plates with rim coloring compared with plates with no coloring (P=0.01). The effect of rim coloring was greater with smaller food portion sizes.The Delboeuf illusion applies to food on a plate. Participants overestimated food portion size on plates with wider and colored rims. These findings may help design plates to influence perceptions of food portion sizes.
View details for DOI 10.1038/ijo.2013.169
View details for Web of Science ID 000335445300006
View details for PubMedID 24005858
To test the effects of a three-year, community-based, multi-component, multi-level, multi-setting (MMM) approach for treating overweight and obese children.Two-arm, parallel group, randomized controlled trial with measures at baseline, 12, 24, and 36months after randomization.Seven through eleven year old, overweight and obese children (BMI≥85th percentile) and their parents/caregivers recruited from community locations in low-income, primarily Latino neighborhoods in Northern California.Families are randomized to the MMM intervention versus a community health education active-placebo comparison intervention. Interventions last for three years for each participant. The MMM intervention includes a community-based after school team sports program designed specifically for overweight and obese children, a home-based family intervention to reduce screen time, alter the home food/eating environment, and promote self-regulatory skills for eating and activity behavior change, and a primary care behavioral counseling intervention linked to the community and home interventions. The active-placebo comparison intervention includes semi-annual health education home visits, monthly health education newsletters for children and for parents/guardians, and a series of community-based health education events for families.Body mass index trajectory over the three-year study. Secondary outcome measures include waist circumference, triceps skinfold thickness, accelerometer-measured physical activity, 24-hour dietary recalls, screen time and other sedentary behaviors, blood pressure, fasting lipids, glucose, insulin, hemoglobin A1c, C-reactive protein, alanine aminotransferase, and psychosocial measures.The Stanford GOALS trial is testing the efficacy of a novel community-based multi-component, multi-level, multi-setting treatment for childhood overweight and obesity in low-income, Latino families.
View details for DOI 10.1016/j.cct.2013.09.001
View details for Web of Science ID 000329265300012
To test a 2-year community- and family-based obesity prevention program for low-income African American girls: Stanford GEMS (Girls' health Enrichment Multi-site Studies).Randomized controlled trial with follow-up measures scheduled at 6, 12, 18, and 24 months.Low-income areas of Oakland, California.African American girls aged 8 to 10 years (N=261) and their parents or guardians.Families were randomized to one of two 2-year, culturally tailored interventions: (1) after-school hip-hop, African, and step dance classes and a home/family-based intervention to reduce screen media use or (2) information-based health education.Changes in body mass index (BMI).Changes in BMI did not differ between groups (adjusted mean difference [95% confidence interval] = 0.04 [-0.18 to 0.27] per year). Among secondary outcomes, fasting total cholesterol level (adjusted mean difference, -3.49 [95% confidence interval, -5.28 to -1.70] mg/dL per year), low-density lipoprotein cholesterol level (-3.02 [-4.74 to -1.31] mg/dL per year), incidence of hyperinsulinemia (relative risk, 0.35 [0.13 to 0.93]), and depressive symptoms (-0.21 [-0.42 to -0.001] per year) decreased more among girls in the dance and screen time reduction intervention. In exploratory moderator analysis, the dance and screen time reduction intervention slowed BMI gain more than health education among girls who watched more television at baseline (P = .02) and/or those whose parents or guardians were unmarried (P = .01).A culturally tailored after-school dance and screen time reduction intervention for low-income, preadolescent African American girls did not significantly reduce BMI gain compared with health education but did produce potentially clinically important reductions in lipid levels, hyperinsulinemia, and depressive symptoms. There was also evidence for greater effectiveness in high-risk subgroups of girls.
View details for Web of Science ID 000283735700006
View details for PubMedID 21041592
African-American girls and women are at high risk of obesity and its associated morbidities. Few studies have tested obesity prevention strategies specifically designed for African-American girls. This report describes the design and baseline findings of the Stanford GEMS (Girls health Enrichment Multi-site Studies) trial to test the effect of a two-year community- and family-based intervention to reduce weight gain in low-income, pre-adolescent African-American girls.Randomized controlled trial with measurements scheduled in girls' homes at baseline, 6, 12, 18 and 24 month post-randomization.Low-income areas of Oakland, CA.Eight, nine and ten year old African-American girls and their parents/caregivers.Girls are randomized to a culturally-tailored after-school dance program and a home/family-based intervention to reduce screen media use versus an information-based community health education Active-Placebo Comparison intervention. Interventions last for 2 years for each participant.Change in body mass index over the two-year study.Recruitment and enrollment successfully produced a predominately low-socioeconomic status sample. Two-hundred sixty one (261) families were randomized. One girl per family is randomly chosen for the analysis sample. Randomization produced comparable experimental groups with only a few statistically significant differences. The sample had a mean body mass index (BMI) at the 74 th percentile on the 2000 CDC BMI reference, and one-third of the analysis sample had a BMI at the 95th percentile or above. Average fasting total cholesterol and LDL cholesterol were above NCEP thresholds for borderline high classifications. Girls averaged low levels of moderate to vigorous physical activity, more than 3 h per day of screen media use, and diets high in energy from fat.The Stanford GEMS trial is testing the benefits of culturally-tailored after-school dance and screen-time reduction interventions for obesity prevention in low-income, pre-adolescent African-American girls.
View details for DOI 10.1016/j.cct.2007.04.007
View details for Web of Science ID 000252584100007
View details for PubMedID 17600772
To examine the effects of cumulative, real-world marketing and brand exposures on young children by testing the influence of branding from a heavily marketed source on taste preferences.Experimental study. Children tasted 5 pairs of identical foods and beverages in packaging from McDonald's and matched but unbranded packaging and were asked to indicate if they tasted the same or if one tasted better.Preschools for low-income children.Sixty-three children (mean +/- SD age, 4.6 +/- 0.5 years; range, 3.5-5.4 years).Branding of fast foods.A summary total taste preference score (ranging from -1 for the unbranded samples to 0 for no preference and +1 for McDonald's branded samples) was used to test the null hypothesis that children would express no preference.The mean +/- SD total taste preference score across all food comparisons was 0.37 +/- 0.45 (median, 0.20; interquartile range, 0.00-0.80) and significantly greater than zero (P<.001), indicating that children preferred the tastes of foods and drinks if they thought they were from McDonald's. Moderator analysis found significantly greater effects of branding among children with more television sets in their homes and children who ate food from McDonald's more often.Branding of foods and beverages influences young children's taste perceptions. The findings are consistent with recommendations to regulate marketing to young children and also suggest that branding may be a useful strategy for improving young children's eating behaviors.
View details for Web of Science ID 000248583000010
View details for PubMedID 17679662
Food-related parenting attitudes are thought to influence children's dietary intake and weight. The objective of this study was to examine the associations between mothers' reports of food-related parenting and children's dietary intake and body mass index (BMI). A sample of 108 Mexican-American fifth-grade children and their mothers were surveyed. Children's height, weight, and three 24-hour dietary recalls were collected. Mothers reported household food insecurity status and food-related parenting attitudes. Correlational analyses were calculated among dietary intake variables, children's BMI percentiles, and food-parenting behaviors. Mothers' pressure on their children to eat was inversely correlated with children's BMI. In food-insecure families, attitudes toward making healthful foods available were inversely associated with children's daily energy intake and BMI. In contrast, in food-secure families, attitudes about making healthful foods available were positively associated with children's fruit intake and percentage energy from fat, and parental modeling of healthful food behaviors was inversely associated with the energy density. In our sample of Mexican-American families, mothers' food-related parenting was associated with their children's weight and dietary intake. These associations differed in food-secure and food-insecure households. Overall, pressure to eat was highly associated with children's weight, but the temporal nature of these relationships cannot be discerned.
View details for DOI 10.1016/j.jada.2006.08.004
View details for Web of Science ID 000241715300023
View details for PubMedID 17081838
Television viewing has been associated with childhood obesity, although the mechanisms that link television viewing to higher BMI have not been established. Therefore, our objectives, in this report, were to describe the amount and types of foods that African-American girls consume while watching television and to examine the associations between African-American girls' BMI and the food they consume while watching television.Data were collected from 210 8- to 10-year-old African-American girls at four field centers by trained and certified nutritionists. Two nonconsecutive 24-hour dietary recalls were collected from each girl. For each eating episode reported, the girls were asked if they had been watching television while eating. Height and weight were collected using standard methods and used to calculate BMI.The data were analyzed separately by field center. The proportion of average daily energy intake that the girls consumed while watching television ranged from 26.9% to 35.0%. At all field centers, 40% to 50% of evening meals were consumed while watching television. None of the Spearman correlations between girls' BMI and the amount and type of foods consumed while watching television or at other times during the day were statistically significant (p > 0.05).This research revealed that a significant proportion of African-American girls' daily energy intake is consumed while watching television. Interventions that target reductions in food consumption while watching television or reducing television viewing may be effective strategies to decrease children's energy intakes. These results support a need for research to test the efficacy of these approaches.
View details for Web of Science ID 000224581800005
View details for PubMedID 15489465
Our goal was to examine 12-week covariability in diet and physical activity changes among 8- to 10-year-old African-American girls and if these changes predicted percent change in BMI.Covariability among percent changes [(post - pre)/pre x 100] in nutrients, food groups, and physical activity was assessed among 127 8- to 10-year-old African-American girls. Pearson correlation and hierarchical linear regression analyses were performed.Percent change in percentage kilocalories from carbohydrate was negatively correlated with percent change in both percentage kilocalories from fat (r = -0.85; p < or = 0.01) and protein (r = -0.51; p < or = 0.01). No statistically significant relationships were observed in percent changes among food group variables. Negative relationships were observed between percent changes in fruit/100% juice and percentage kilocalories from fat (r = -0.20; p < or = 0.05) and between percent changes in minutes of moderate-to-vigorous and sedentary activity (r = -0.60; p < or = 0.01). No significant associations were observed between percent change in moderate-to-vigorous physical activity and diet variables or percent change in BMI or waist circumference and percent change in diet or physical activity.No relationships were observed between percent changes in physical activity and dietary variables. Percent change in diet and/or physical activity did not predict percent change in BMI. This may have been due to the small sample size, the small changes in diet or physical activity, the short duration of the intervention, or because data from different interventions were combined. Understanding these relationships could have significant implications for addressing the obesity epidemic.
View details for Web of Science ID 000224581800007
View details for PubMedID 15489467
Television viewing is associated with childhood obesity. Eating during viewing and eating highly advertised foods are 2 of the hypothesized mechanisms through which television is thought to affect children's weight.Our objectives were to describe the amounts and types of foods that children consume while watching television, compare those types with the types consumed at other times of the day, and examine the associations between children's body mass index (BMI) and the amounts and types of foods consumed during television viewing.Data were collected from 2 samples. The first sample consisted of ethnically diverse third-grade children, and the second consisted predominantly of Latino fifth-grade children. Three nonconsecutive 24-h dietary recalls were collected from each child. For each eating episode reported, children were asked whether they had been watching television. Height and weight were measured by using standard methods and were used to calculate BMI.On weekdays and weekend days, 17-18% and approximately 26% of total daily energy, respectively, were consumed during television viewing in the 2 samples. Although the fat content of the foods consumed during television viewing did not differ significantly from that of the foods consumed with the television off, less soda, fast food, fruit, and vegetables were consumed with the television on. The amount of food consumed during television viewing was not associated with children's BMI, but in the third-grade sample, the fat content of foods consumed during television viewing was associated with BMI.A significant proportion of children's daily energy intake is consumed during television viewing, and the consumption of high-fat foods on weekends may be associated with BMI in younger children.
View details for Web of Science ID 000221553500021
View details for PubMedID 15159240
Quality control methods are key components of dietary assessment, but have rarely been evaluated.One hundred forty-four 8-10-year-old African-American girls at three field centers completed two 24-h dietary recalls at baseline before a pilot weight gain prevention intervention (one recall collected in-person and one by telephone). The dietary recall data were initially reviewed by the dietary interviewer (Phase 1), then by a local lead nutritionist at the field center (Phase 2), and then by the Nutrition Coordinating Center (NCC) (Phase 3); any differences identified by NCC were reconciled (Phase 4). Bland-Altman and generalizability theory methods were used to assess agreement of consumption for selected food variables and nutrients between phases.Only small differences occurred. Quality control procedures primarily reduced the variances of nutrients rather than caused the means to shift. Most of the variability among phases was due to individual level variability in dietary intake.Decisions to review dietary recall data beyond local review should be based on the level of precision and accuracy required for the study outcomes and the availability of financial resources.
View details for DOI 10.1016/j.ypmed.2003.10.014
View details for Web of Science ID 000221125700002
View details for PubMedID 15072855
To test the feasibility, acceptability, and potential efficacy of after-school dance classes and a family-based intervention to reduce television viewing, thereby reducing weight gain, among African-American girls.Twelve-week, 2-arm parallel group, randomized controlled trial.Low-income neighborhoods.Sixty-one 8-10-year-old African-American girls and their parents/guardians.The treatment intervention consisted of after-school dance classes at 3 community centers, and a 5-lesson intervention, delivered in participants' homes, and designed to reduce television, videotape, and video game use. The active control intervention consisted of disseminating newsletters and delivering health education lectures.Implementation and process measures, body mass index, waist circumference, physical activity measured by accelerometry, self-reported media use, and meals eaten with TV.Recruitment and retention goals were exceeded. High rates of participation were achieved for assessments and intervention activities, except where transportation was lacking. All interventions received high satisfaction ratings. At follow up, girls in the treatment group, as compared to the control group, exhibited trends toward lower body mass index (adjusted difference = -.32 kg/m2, 95% confidence interval [CI] -.77, .12; Cohen's d = .38 standard deviation units) and waist circumference (adjusted difference = -.63 cm, 95% CI -1.92, .67; d = .25); increased after-school physical activity (adjusted difference = 55.1 counts/minute, 95% CI -115.6, 225.8; d = .21); and reduced television, videotape, and video game use (adjusted difference = -4.96 hours/week, 95% CI -11.41, 1.49; d = .40). The treatment group reported significantly reduced household television viewing (d = .73, P = .007) and fewer dinners eaten while watching TV (adjusted difference = -1.60 meals/week, 95% CI -2.99, -.21; d = .59; P = .03). Treatment group girls also reported less concern about weight (d = .60; P = .03), and a trend toward improved school grades (d = .51; P = .07).This study confirmed the feasibility, acceptability, and potential efficacy of using dance classes and a family-based intervention to reduce television viewing, thereby reducing weight gain, in African-American girls.
View details for PubMedID 12713212
Policy and clinical decisions regarding children's nutrition are often based on dietary intake estimates from self-reports. The accuracy of these estimates depends on memory of both the type of food eaten and the amount consumed. Although children's self-reports of food intake are widely used, there is little research on their ability to estimate food portions.To assess the validity of children's estimates of the food portions they consume by means of 2 types of measurement aids: standard 2-dimensional food portion visuals and manipulative props.Randomized controlled trial.Fifty-four African American girls aged 8 to 12 years.Girls were served a standard meal and actual intake was assessed by weighing food portions before and after the meal. On completion of the meal, dietitians collected food recalls and portion size estimates from the girls by means of both manipulative props and 2-dimensional food portion visuals, administered in a randomized order.Absolute value percentage differences between actual and estimated grams of food consumed averaged 58.0% (SD, 102.7%) for manipulative props and 32.8% (SD, 72.8%) for 2-dimensional food portion visuals. Spearman correlations between actual and estimated intakes with both portion size measurement aids were high (range, r = 0.56 to 0.79; all P<.001), with the exception of bread intake (r = 0.16, P =.43). Correlations with actual intakes did not differ significantly between the 2 methods.Children's self-reported portion size estimates are appropriate for ranking children's relative intakes, but they result in sizable errors in quantitative estimates of food and energy intakes. Caution should be used in interpreting quantitative dietary intake estimates derived from children's self-reports.
View details for Web of Science ID 000177859400006
View details for PubMedID 12197792
Food insecurity is a critical variable for understanding the nutritional status of low-income populations. However, limited research is available on the relation between household food insecurity and children's nutritional status.Our objective was to examine the relations among household food insecurity, household food supplies, and school-age children's dietary intakes and body mass indexes (BMIs).A sample of 124 predominantly Hispanic, fifth-grade children and their mothers were surveyed as part of a school-based obesity-prevention program. Data on the children's weights and heights were collected and three 24-h dietary recalls were conducted. The mothers provided reports of household food insecurity and household food supplies.Food insecurity was negatively associated with the children's BMIs and household food supplies but not with the children's food intakes. However, a secondary analysis showed that as payday approached, children from the most food-insecure households had significant decreases in energy intakes and meat consumption.This is one of the first studies to report a significant association between food insecurity and children's nutritional status. The ages and sex-adjusted BMIs of the food-insecure children were lower than those of the food-secure children but were still within the normal range. The lower BMIs in the food-insecure children may have been due to short-term, yet periodic food restrictions that resulted as household food supplies diminished before payday. Future research is needed to assess the physiologic and psychological effects of periodic food restriction on children's health.
View details for Web of Science ID 000176378500025
View details for PubMedID 12081837
Developmental theory suggests that children learn from their experiences. However, little is known about preschool children's interpretation of their daily food experiences. Therefore, the purpose of this research was to describe the criteria preschool children use to classify foods and their interpretation of their daily food experiences.Semistructured interviews and observations of children's play in toy kitchens were conducted with children enrolled in public preschool programs.Data were collected over a 2-year period. During the first year of the study, observations and interviews were collected from 24 children. Interviews with an additional 79 children were conducted the following year.The variables measured included the children's criteria for food classification and their play behaviors in a toy kitchen.The children relied primarily on physical characteristics such as color, shape, and texture to classify foods. The activities that children demonstrated during play sessions included meal planning, food preparation, table preparation, serving food, eating, and cleaning. Pattern coding of the observational data revealed variability in (1) boys' and girls' kitchen play, (2) children's food selection and preparation methods and postmeal clean-up activities, and (3) children's responses to picky eating.These data may be used to develop a play-based nutrition education program.
View details for Web of Science ID 000174928400004
View details for PubMedID 12047815
Identifying parental behaviors that influence childhood obesity is critical for the development of effective prevention and treatment programs. Findings from a prior laboratory study suggest that parents who impose control over their children's eating may interfere with their children's ability to regulate intake, potentially resulting in overweight. These findings have been widely endorsed; however, the direct relationship between parental control of children's intake and their children's degree of overweight has not been shown in a generalized sample.This study surveyed 792 third-grade children with diverse ethnic and socioeconomic backgrounds from 13 public elementary schools. Parental control over children's intake was assessed through telephone interviews using a state-of-the-art instrument, and children were measured for height, weight, and triceps skinfold thickness.Counter to the hypothesis, parental control over children's intake was inversely associated with overweight in girls, as measured by body mass index, r = -0.12, p < 0.05, and triceps skinfolds, r = -0.11, p < 0.05. This weak relationship became only marginally significant when controlling for parents' perceptions of their own weight, level of household education, and children's age. No relationship between parental control of children's intake and their children's degree of overweight was found in boys.Previous observations of the influence of parental control over children's intake in middle-class white families did not generalize to 8- to 9-year-olds in families with diverse socioeconomic and ethnic backgrounds. The present findings reveal a more complex relationship between parental behaviors and children's weight status.
View details for Web of Science ID 000168685300005
View details for PubMedID 11346672
The purpose of this research was to describe the context created by students as they worked in groups on a nutrition computer-assisted instruction (CAI) program. Students worked on the program in groups of three. Observational methods were used to collect data from students in two sixth-grade classrooms that were part of an experimental program designed to restructure the educational process. Thirty-two students, from 12 groups, were observed as they completed the program. The groups were assigned by the teachers according to standard principles of cooperative learning. Students completed "Ship to Shore," a program designed specifically for this research. The program required three to five 50-minute classroom periods to complete. The objectives of the program were to change children's knowledge structure of basic nutrition concepts and to increase children's critical thinking skills related to nutrition concepts. We collected observational data focused on three domains: (1) student-computer interaction, (2) student-student interaction, and (3) students' thinking and learning skills. Grounded theory methods were used to analyze the data. Specifically, the constant-comparative method was used to develop open coding categories, defined by properties and described by dimensions. The open coding categories were in turn used in axial coding to differentiate students' learning styles. Five styles of student interaction were defined. These included (1) dominant directors (n = 6; 19%), (2) passive actors (n = 5; 16%), (3) action-oriented students (n = 7; 22%), (4) content-oriented students (n = 8; 25%), and (5) problem solvers (n = 5; 16%). The "student style" groups were somewhat gender specific. The dominant directors and passive actors were girls and the action-oriented and content-oriented students were boys. The problem solvers group was mixed gender. Children's responses to computer-based nutrition education are highly variable. Based on the results of this research, nutrition educators may recommend that nutrition CAI programs be implemented in mixed gender groups.
View details for Web of Science ID 000166922800003
View details for PubMedID 12031199
The objective of this research was to document the extent to which elements of fantasy, curiosity, and challenge are used in existing nutrition education materials. A content analysis of 30 nutrition education curricula designed for elementary and middle-school grades was conducted. Print curricula, computer software, videotapes, and puppet shows were included in the sample. The use of challenge, curiosity, and fantasy, as defined in the Theory of Intrinsically Motivating Instruction (TIMI), was assessed in each curriculum. Approximately half of the curricula included elements of challenge, curiosity, or fantasy. All of the nonprint curricula and 30% of the print curricula incorporated these characteristics. Curiosity was most frequently used in these curricula, followed by fantasy and then challenge. The TIMI provided a useful theory to examine the instructional approaches frequently used in school-based nutrition education programs. Nutritionists may apply concepts from the TIMI to the design of future curricula so that these programs are interesting and entertaining for their target audience.
View details for Web of Science ID 000166922800004
View details for PubMedID 12031200