Hollie A. Raynor

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.

Effects of deprivation on hedonics and reinforcing value of food

Eating is influenced by both the hedonic preferences and reinforcing value of food. Incentive salience theory predicts these are separate influences. This study tested whether hedonics reliably change as a function of increasing the reinforcing value of food by deprivation in 17 non-obese, non-dietary restrained females. Baseline measures of hedonics for pleasant (chocolate milk), unpleasant (lemon juice) and neutral (water) tastes were determined under deprived conditions. Participants were then randomly assigned to fed or maintained in deprived conditions, and after food consumption, a second determination of hedonics was obtained, followed by assessing the reinforcing value of food. Hedonics was measured by subjective ratings and behavioral observations in a taste reactivity paradigm. Results showed food was more reinforcing for the deprived than the fed group, but no influences of group were observed for the subjective or objective hedonic measures. These results suggest that hedonics and the reinforcing value of food are separate processes in humans, and they may independently influence eating behavior.

The effect of reinforcement or stimulus control to reduce sedentary behavior in the treatment of pediatric obesity.

Obese children were randomly assigned to a family-based behavioral treatment that included either stimulus control or reinforcement to reduce sedentary behaviors. Significant and equivalent decreases in sedentary behavior and high energy density foods, increases in physical activity and fruits and vegetables, and decreases in standardized body mass index (z-BMI) were observed. Children who substituted active for sedentary behaviors had significantly greater z-BMI changes at 6 (-1.21 vs. -0.76) and 12 (-1.05 vs. -0.51) months, respectively. Substitution of physically active for sedentary behaviors and changes in activity level predicted 6- and 12-month z-BMI changes. Results suggest stimulus control and reinforcing reduced sedentary behaviors are equivalent ways to decrease sedentary behaviors, and behavioral economic relationships in eating and activity may mediate the effects of treatment.

Experimental research on the relation between food price changes and food-purchasing patterns: a targeted review

One way in which to modify food purchases is to change prices through tax policy, subsidy policy, or both. We reviewed the growing body of experimental research conducted in the laboratory and in the field that investigates the following: the extent to which price changes influence purchases of targeted and nontargeted foods, total energy, or macronutrients purchased; the interaction of price changes with adjunctive interventions; and moderators of sensitivity to price changes. After a brief overview of economic principles and observational research that addresses these issues, we present a targeted review of experimental research. Experimental research suggests that price changes modify purchases of targeted foods, but research on the overall nutritional quality of purchases is mixed because of substitution effects. There is mixed support for combining price changes with adjunctive interventions, and there are no replicated findings on moderators to price sensitivity in experiments. Additional focused research is needed to better inform food policy development with the aim of improving eating behavior and preventing obesity.

BEHAVIORAL THERAPY IN THE TREATMENT OF PEDIATRIC OBESITY

This article was designed to make a strong case for the importance of studying behavior and using behavioral therapy in the treatment of pediatric obesity. Behavioral treatments have been the most studied approaches to pediatric obesity, with great success. Six studies that provided long-term results are presented, and ideas for translating behavioral therapy into common pediatric practice are presented. Additional progress is needed to incorporate new findings in learning and behavioral neuroscience into clinical interventions and to integrate behavioral therapy with pharmacologic interventions and genetic predispositions and new advances in nutrition and exercise science.

The relative-reinforcing value of food under differing levels of food deprivation and restriction.

Food deprivation and restriction both increase food consumption. Food deprivation also increases the reinforcing value of food, but it is unknown if food restriction alone or combined with deprivation increases the reinforcing value of food. Forty, normal-weight, college-aged, unrestrained females were randomized to one of four conditions that crossed food deprivation (Dep) and restriction (Res): Dep/Res, Dep/No Res, No Dep/Res, No Dep/No Res. All participants arrived at least 13h food-deprived, and non-deprived participants consumed at least 365cal from a drink during the session. Restriction was manipulated by placing snack food in front of participants, without access for 15min during the session, or having no snack food placed in front of participants. Following the experimental manipulations, participants completed a computer choice task to determine the reinforcing value of food. Repeated measures analysis of variance found a significant main effect of deprivation (p<0.05) and trials (p<0.001) for food points earned. Deprived participants found food to be more reinforcing, and the reinforcing value of food decreased over time. This suggests that while short-term food deprivation increases the relative-reinforcing value of food, short-term food restriction has no effect on the relative-reinforcing value of food in unrestrained eaters.

Differential functional magnetic resonance imaging response to food pictures in successful weight-loss maintainers relative to normal-weight and obese controls

BACKGROUND Prior research indicates that successful weight-loss maintainers (SWLs) work harder than people of normal weight to maintain their weight loss, including greater dietary restriction of fat and higher physical activity levels. However, little work to date has examined how SWLs differ biologically from normal-weight (NW) and obese controls. OBJECTIVE The objective was to compare the brain responses of SWLs to food pictures with those of NW and obese controls. DESIGN Blood oxygen level-dependent responses to high- and low-energy food pictures were measured in 18 NW controls, 16 obese controls, and 17 SWLs. RESULTS Group differences were identified in 4 regions, which indicated significant change in activation in response to the food pictures. SWLs showed greater activation in the left superior frontal region and right middle temporal region than did NW and obese controls-a pattern of results confirmed in exploratory voxel-wise analyses. Obese controls also showed greater activation in a bilateral precentral region. CONCLUSIONS These results suggest that SWLs show greater activation in frontal regions and primary and secondary visual cortices-a pattern consistent with greater inhibitory control in response to food cues and greater visual attention to the food cues. A greater engagement of inhibitory control regions in response to food cues as well as a greater monitoring of foods may promote control of food intake and successful weight-loss maintenance.

Changes in Children’s Sleep Duration on Food Intake, Weight, and Leptin

OBJECTIVE: To examine the effect of experimental changes in children’s sleep duration on self-reported food intake, food reinforcement, appetite-regulating hormones, and measured weight. METHODS: Using a within-subjects, counterbalanced, crossover design, 37 children, 8 to 11 years of age (27% overweight/obese) completed a 3-week study. Children slept their typical amount at home for 1 week and were then randomized to either increase or decrease their time in bed by 1.5 hours per night for 1 week, completing the alternate schedule on the third week. Primary outcomes were dietary intake as assessed by 24-hour dietary recalls, food reinforcement (ie, points earned for a food reward), and fasting leptin and ghrelin. The secondary outcome was child weight. RESULTS: Participants achieved a 2 hour, 21 minute difference in the actigraph defined sleep period time between the increase and decrease sleep conditions (P < .001). Compared with the decrease sleep condition, during the increase condition, children reported consuming an average of 134 kcal/day less (P < .05), and exhibited lower fasting morning leptin values (P < .05). Measured weights were 0.22 kg lower during the increase sleep than the decrease sleep condition (P < .001). There were no differences in food reinforcement or in fasting ghrelin. CONCLUSIONS: Compared with decreased sleep, increased sleep duration in school-age children resulted in lower reported food intake, lower fasting leptin levels, and lower weight. The potential role of sleep duration in pediatric obesity prevention and treatment warrants further study.

A cost-analysis of adopting a healthful diet in a family-based obesity treatment program

OBJECTIVE To assess dietary costs during a family-based pediatric obesity intervention. DESIGN Families were randomized to one of two groups. Dietary and cost data were collected from a parent or child using three 24-hour recalls: at baseline, 6 months, and 12 months. SUBJECTS Thirty-one families with an obese 8- to 12-year-old child entered treatment, with complete dietary data provided from 20 families. INTERVENTION The 20-week behavior modification intervention emphasized increasing diet nutrient-density. Families attended group and individual sessions or group sessions. MAIN OUTCOME MEASURES Energy intake; percent of energy from protein, fat, and carbohydrate; servings and percent servings from food groups classified by nutrient density; and daily food costs. STATISTICAL ANALYSES PERFORMED Mixed analyses of variance, with group as the between-subject factor, and time as the within-subject factor. RESULTS No significant effect of group was found in any analyses. Significant decreases in percent overweight were observed at 6 and 12 months for children (-10.0+/-8.7 and -8.0+/-10.3, respectively) (mean+/-standard deviation) and parents (-6.7+/-10.3 and -5.3+/-14.1). Energy intake for parents and children combined significantly decreased from baseline (1,881+/-462) to 6 months (1,412+/-284), and 1 year (1,338+/-444). Servings from low-nutrient-dense foods significantly decreased from baseline (34.7+/-16.2) to 6 months (16.0+/-8.6) and 1 year (18.6+/-9.2), causing a significant increase in diet nutrient density. Dietary cost did not change at 6 months, but significantly decreased from baseline to 1 year (

B-MOBILE - A Smartphone-Based Intervention to Reduce Sedentary Time in Overweight/Obese Individuals: A Within-Subjects Experimental Trial

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