Leonard H. Epstein

A Randomized Trial of the Effects of Reducing Television Viewing and Computer Use on Body Mass Index in Young Children

OBJECTIVE To assess the effects of reducing television viewing and computer use on childrens body mass index (BMI) as a risk factor for the development of overweight in young children. DESIGN Randomized controlled clinical trial. SETTING University childrens hospital. PARTICIPANTS Seventy children aged 4 to 7 years whose BMI was at or above the 75th BMI percentile for age and sex. INTERVENTIONS Children were randomized to an intervention to reduce their television viewing and computer use by 50% vs a monitoring control group that did not reduce television viewing or computer use. MAIN OUTCOME MEASURES Age- and sex-standardized BMI (zBMI), television viewing, energy intake, and physical activity were monitored every 6 months during 2 years. RESULTS Children randomized to the intervention group showed greater reductions in targeted sedentary behavior (P < .001), zBMI (P < .05), and energy intake (P < .05) compared with the monitoring control group. Socioeconomic status moderated zBMI change (P = .01), with the experimental intervention working better among families of low socioeconomic status. Changes in targeted sedentary behavior mediated changes in zBMI (P < .05). The change in television viewing was related to the change in energy intake (P < .001) but not to the change in physical activity (P =.37). CONCLUSIONS Reducing television viewing and computer use may have an important role in preventing obesity and in lowering BMI in young children, and these changes may be related more to changes in energy intake than to changes in physical activity.

Effects of decreasing sedentary behavior and increasing activity on weight change in obese children.

Obese children 8-12 years old from 61 families were randomized to treatment groups that targeted increased exercise, decreased sedentary behaviors, or both (combined group) to test the influence of reinforcing children to be more active or less sedentary on child weight change. Significant decreases in percentage overweight were observed after 4 months between the sedentary and the exercise groups (-19.9 vs. -13.2). At 1 year, the sedentary group had a greater decrease in percentage overweight than did the combined and the exercise groups (-18.7 vs. -10.3 and -8.7) and greater decrease in percentage of body fat (-4.7 vs. -1.3). All groups improved fitness during treatment and follow-up. Children in the sedentary group increased their liking for high-intensity activity and reported lower caloric intake than did children in the exercise group. These results support the goal of reducing time spent in sedentary activities to improve weight loss.

The Relationship Between Motor Proficiency and Physical Activity in Children

OBJECTIVES. Youth with better motor abilities may find it easier to be physically active and may be more likely to engage in physical activity compared with peers with poorer motor competence. The purpose of this study was to examine the relationship between motor proficiency and physical activity in 8- to 10-year-old children. Self-efficacy toward physical activity was also assessed. METHODS. Sixty-five children (34 girls and 31 boys) were studied. Childrens physical activity was assessed by the Manufacturing Technologies Incorporated/Computer Science and Applications Incorporated model 7164 accelerometer, and their motor proficiency was determined by the Bruininks-Oseretsky Test of Motor Proficiency. The Childrens Self-Perceptions of Adequacy in and Predilection for Physical Activity scale measured childrens self-perceptions of adequacy in performing and desire to participate in physical activities. RESULTS. Childrens motor proficiency was positively associated with activity counts and percentage of time in moderate and moderate-to-vigorous intensity physical activity and inversely related to percentage of time in sedentary activity. Children in the greatest quartile of motor proficiency were the most physically active compared with children with lower levels of motor proficiency who had similar levels of physical activity. Children with greater standardized BMI were less physically active, more sedentary, and had poorer motor proficiency compared with children with a lower standardized BMI. Childrens Self-Perceptions of Adequacy in and Predilection for Physical Activity scores were positively associated with Bruininks-Oseretsky Test of Motor Proficiency standard score for boys. Childrens motor proficiency explained an additional 8.7% of the variance in physical activity in multiple linear regression after controlling for factors that may influence physical activity. CONCLUSIONS. Motor proficiency is positively associated with physical activity and inversely associated with sedentary activity in children, but there may be a threshold of motor proficiency above which children may be the most physically active. Childrens motor proficiency may be an appropriate target for increasing physical activity in youth.

Family-Based Obesity Treatment, Then and Now: Twenty-Five Years of Pediatric Obesity Treatment

OBJECTIVE Family-based treatments for pediatric obesity were developed over 25 years ago. Over that time, youth have become more obese and the environment more obesiogenic, which may influence efficacy of pediatric weight control. Mixed-effects regression models were used to compare the efficacy of programs initiated 20 to 25 years ago to current programs through 24-month follow-up, as well as to reanalyze 10-year outcomes of previous research using contemporary measures and analytic strategies. MAIN OUTCOME MEASURES z-BMI and percent overweight. RESULTS Results showed significant reductions over time, with no differences in z-BMI change for older versus contemporary studies. Age was a predictor of z-BMI up to 24 months, with younger children showing larger change. Mixed-effects regression models replicated previous long-term effects of family-based interventions. Gender was a predictor of long-term z-BMI change, with girls benefiting more over time than did boys. CONCLUSION The efficacy of the family-based behavioral approach to treating pediatric obesity replicates over a 25-year period. Challenges in evaluating treatment effects over time are discussed. Ideas for studying choice of treatments that vary in effect size and for strengthening family-based behavioral treatments are noted.

Lifestyle Interventions in the Treatment of Childhood Overweight: A Meta-Analytic Review of Randomized Controlled Trials

CONTEXT Evaluating the efficacy of pediatric weight loss treatments is critical. OBJECTIVE This is the first meta-analysis of the efficacy of RCTs comparing pediatric lifestyle interventions to no-treatment or information/education-only controls. DATA SOURCES Medline, PsycINFO, and Cochrane Controlled Trials Register. STUDY SELECTION Fourteen RCTs targetting change in weight status were eligible, yielding 19 effect sizes. DATA EXTRACTION Standardized coding was used to extract information on design, participant characteristics, interventions, and results. DATA SYNTHESIS For trials with no-treatment controls, the mean effect size was 0.75 (k = 9, 95% confidence interval [CI] = 0.52-0.98) at end of treatment and 0.60 (k = 4, CI = 0.27-0.94) at follow-up. For trials with information/education-only controls, the mean ES was 0.48 (k = 4, CI = 0.13-0.82) at end of treatment and 0.91 (k = 2, CI = 0.32-1.50) at follow-up. No moderator effects were identified. CONCLUSIONS Lifestyle interventions for pediatric overweight are efficacious in the short term with some evidence for extended persistence. Future research is required to identify moderators and mediators and to determine the optimal length and intensity of treatment required to produce enduring changes in weight status.

Dietary Variety, Energy Regulation, and Obesity

Increased variety in the food supply may contribute to the development and maintenance of obesity. Thirty-nine studies examining dietary variety, energy intake, and body composition are reviewed. Animal and human studies show that food consumption increases when there is more variety in a meal or diet and that greater dietary variety is associated with increased body weight and fat. A hypothesized mechanism for these findings is sensory-specific satiety, a phenomenon demonstrating greater reductions in hedonic ratings or intake of foods consumed compared with foods not consumed. Nineteen studies documenting change in preference, intake, and hedonic ratings of food after a food has been eaten to satiation in animals and humans are reviewed, and the theory of sensory-specific satiety is examined. The review concludes with the relevance of oral habituation theory as a unifying construct for the effects of variety and sensory-specific satiety, clinical implications of dietary variety and sensory-specific satiety on energy regulation, and suggestions for future research.

Food Reinforcement and Eating: A Multilevel Analysis

Eating represents a choice among many alternative behaviors. The purpose of this review is to provide an overview of how food reinforcement and behavioral choice theory are related to eating and to show how this theoretical approach may help organize research on eating from molecular genetics through treatment and prevention of obesity. Special emphasis is placed on how food reinforcement and behavioral choice theory are relevant to understanding excess energy intake and obesity and how they provide a framework for examining factors that may influence eating and are outside of those that may regulate energy homeostasis. Methods to measure food reinforcement are reviewed, along with factors that influence the reinforcing value of eating. Contributions of neuroscience and genetics to the study of food reinforcement are illustrated by using the example of dopamine. Implications of food reinforcement for obesity and positive energy balance are explored, with suggestions for novel approaches to obesity treatment based on the synthesis of behavioral and pharmacological approaches to food reinforcement.

Reinforcing value of food in obese and non-obese women

Food is a powerful reinforcer, and individual differences in the reinforcing efficacy of food may provide a mechanism to explain the excess intake and positive energy balance responsible for obesity. The present study tested the hypothesis that eating palatable food would be more reinforcing than engaging in sedentary activities (e.g. playing computer games) for obese in comparison to non-obese non-dietary restrained female college students. Subjects could choose to eat food or engage in sedentary activities based on their responding in a computer-generated concurrent schedules task. The reinforcement schedule associated with earning access to sedentary activities was held at variable ratio 2 (VR2) while the food reinforcement schedule was set at VR2 in the first trial of the choice task and doubled across the four subsequent trials from VR4 to VR32. Choice and consumption results indicated that eating was significantly more reinforcing than engaging in sedentary activities for obese subjects than non-obese subjects. Hedonics for the activities and foods were not correlated with total food reinforcers earned and did not differ between the groups. These results confirm the hypothesis that eating food is more reinforcing than selected alternative activities to a greater extent for obese than for non-obese young women.

Food reinforcement, the dopamine D2 receptor genotype, and energy intake in obese and nonobese humans.

The authors measured food reinforcement, polymorphisms of the dopamine D2 receptor (DRD2) and dopamine transporter (DAT1) genes, and laboratory energy intake in 29 obese and 45 nonobese humans 18-40 years old. Food reinforcement was greater in obese than in nonobese individuals, especially in obese individuals with the TaqI A1 allele. Energy intake was greater for individuals high in food reinforcement and greatest in those high in food reinforcement with the TaqI A1 allele. No effect of the DAT1 genotype was observed. These data show that individual differences in food reinforcement may be important for obesity and that the DRD2 genotype may interact with food reinforcement to influence energy intake.

Youth at Risk for Obesity Show Greater Activation of Striatal and Somatosensory Regions to Food

Obese humans, compared with normal-weight humans, have less striatal D2 receptors and striatal response to food intake; weaker striatal response to food predicts weight gain for individuals at genetic risk for reduced dopamine (DA) signaling, consistent with the reward-deficit theory of obesity. Yet these may not be initial vulnerability factors, as overeating reduces D2 receptor density, D2 sensitivity, reward sensitivity, and striatal response to food. Obese humans also show greater striatal, amygdalar, orbitofrontal cortex, and somatosensory region response to food images than normal-weight humans do, which predicts weight gain for those not at genetic risk for compromised dopamine signaling, consonant with the reward-surfeit theory of obesity. However, after pairings of palatable food intake and predictive cues, DA signaling increases in response to the cues, implying that eating palatable food contributes to increased responsivity. Using fMRI, we tested whether normal-weight adolescents at high- versus low-risk for obesity showed aberrant activation of reward circuitry in response to receipt and anticipated receipt of palatable food and monetary reward. High-risk youth showed greater activation in the caudate, parietal operculum, and frontal operculum in response to food intake and in the caudate, putamen, insula, thalamus, and orbitofrontal cortex in response to monetary reward. No differences emerged in response to anticipated food or monetary reward. Data indicate that youth at risk for obesity show elevated reward circuitry responsivity in general, coupled with elevated somatosensory region responsivity to food, which may lead to overeating that produces blunted dopamine signaling and elevated responsivity to food cues.