C.A. Hardman

Increasing children's fruit and vegetable consumption: a peer-modelling and rewards-based intervention

Objective: To evaluate a peer-modelling and rewards-based intervention designed to increase childrens fruit and vegetable consumption.Design: Over a 5-month period, children in an experimental and a control school were presented with fruit and vegetables at lunchtime. Children aged 5–7 y also received fruit at snacktime (mid-morning). The intervention was implemented in the experimental school and levels of fruit and vegetable consumption were measured at baseline, intervention and at 4-month follow-up.Setting: Two inner-city London primary schools.Subjects: In total, 749 children aged 5–11 y.Intervention: Over 16 days children watched video adventures featuring heroic peers (the Food Dudes) who enjoy eating fruit and vegetables, and received small rewards for eating these foods themselves. After 16 days there were no videos and the rewards became more intermittent.Main outcome measures: Consumption was measured (i) at lunchtime using a five-point observation scale; (ii) at snacktime using a weighed measure; (iii) at home using parental recall.Results: Compared to the control school, lunchtime consumption in the experimental school was substantially higher at intervention and follow-up than baseline (P<0.001), while snacktime consumption was higher at intervention than baseline (P<0.001). The lunchtime data showed particularly large increases among those who initially ate very little. There were also significant increases in fruit and vegetable consumption at home (P<0.05).Conclusions: The intervention was effective in bringing about substantial increases in childrens consumption of fruit and vegetables.Sponsorship: Horticultural Development Council, Fresh Produce Consortium, ASDA, Co-operative Group, Safeway, Sainsbury, Somerfield, Tesco and Birds Eye Walls.

Increasing parental provision and children's consumption of lunchbox fruit and vegetables in Ireland: the Food Dudes intervention.

Background/Objectives:Previous research in the United Kingdom, where there is a school canteen system, has shown that the Food Dudes intervention substantially increases childrens fruit and vegetable consumption. The current study evaluated its effectiveness in Ireland where school meals are not provided and children bring food to school in lunchboxes.Subjects/Methods:Participants were 4- to 11-year-old children attending two primary schools; the schools were randomly assigned to experimental or control conditions (n=228 and 207, respectively). During the 16-day intervention in the experimental school, children watched video adventures featuring the heroic Food Dudes, and received small rewards for eating fruit and vegetables provided. In both schools, parental provision and childrens consumption of fruit and vegetables in the lunchboxes were assessed at baseline and 12-month follow-up (Lunchbox measures). Fruit and vegetables were provided in both schools over an 8-day baseline phase and the 16-day intervention, and childrens consumption was measured (school-provided food measures).Results:Relative to baseline, consumption of the school-provided foods increased during the intervention in the experimental school (P<0.001), whereas in the control school it showed a significant decline. At 12-month follow-up, parents in the experimental school provided and their children consumed significantly more lunchbox fruit, vegetables and juice relative to baseline and to the control school (P<0.001 in all instances).Conclusions:The Food Dudes intervention was effective in changing parental provision and childrens consumption of lunchbox fruit and vegetables in Ireland.

Playing a computer game during lunch affects fullness, memory for lunch, and later snack intake

BACKGROUND The presence of distracting stimuli during eating increases the meal size and could thereby contribute to overeating and obesity. However, the effects of within-meal distraction on later food intake are less clear. OBJECTIVE We sought to test the hypothesis that distraction inhibits memory encoding for a meal, which, in turn, increases later food intake. DESIGN The current study assessed the effects of playing solitaire (a computerized card-sorting game) during a fixed lunch, which was eaten at a fixed rate, on memory for lunch and food intake in a taste test 30 min later. A between-subjects design was used with 44 participants. Participants in the no-distraction group ate the same lunch in the absence of any distracting stimuli. RESULTS Distracted individuals were less full after lunch, and they ate significantly more biscuits in the taste test than did nondistracted participants (mean intake: 52.1 compared with 27.1 g; P = 0.017). Furthermore, serial-order memory for the presentation of the 9 lunch items was less accurate in participants who had been distracted during lunch. CONCLUSIONS These findings provide further evidence that distraction during one meal has the capacity to influence subsequent eating. They may also help to explain the well-documented association between sedentary screen-time activities and overweight.

Will smaller plates lead to smaller waists? A systematic review and meta-analysis of the effect that experimental manipulation of dishware size has on energy consumption

It has been suggested that providing consumers with smaller dishware may prove an effective way of helping people eat less and preventing weight gain, but experimental evidence supporting this has been mixed. The objective of the present work was to examine the current evidence base for whether experimentally manipulated differences in dishware size influence food consumption. We systematically reviewed studies that experimentally manipulated the dishware size participants served themselves at a meal with and measured subsequent food intake. We used inverse variance meta‐analysis, calculating the standardized mean difference (SMD) in food intake between smaller and larger dishware size conditions. Nine experiments from eight publications were eligible for inclusion. The majority of experiments found no significance difference in food intake when participants ate from smaller vs. larger dishware. With all available data included, analysis indicated a marginal effect of dishware size on food intake, with larger dishware size associated with greater intake. However, this effect was small and there was a large amount of heterogeneity across studies (SMD: −0.18, 95% confidence interval: −0.35, 0.00, I2 = 77%). Evidence to date does not show that dishware size has a consistent effect on food intake, so recommendations surrounding the use of smaller plates/dishware to improve public health may be premature.

Effects of rewards, peer-modelling and pedometer targets on children's physical activity: A school-based intervention study

This study evaluated a physical activity intervention for children that comprised peer-modelling, pedometer step goals and tangible rewards. A version of the intervention without the reward component was also tested. Participants (n = 386) were from three primary schools, which were randomly assigned to one of three conditions: (i) full intervention, where children received “Fit ‘n’ Fun Dude” peer-modelling materials and were given daily pedometer goals to receive rewards, (ii) no-rewards intervention, where children received peer-modelling materials and pedometer goals but rewards were not used and (iii) control, where children wore pedometers with no further intervention. Physical activity was measured at baseline, intervention and at the end of a 14-week ‘taper’ phase. During the intervention, the full intervention school showed the largest increase in physical activity relative to baseline (+2456 steps per day, p < 0.001). There was a smaller increase in the no-rewards school (+1033 steps per day, p < 0.03), and no significant change in the control. At the end of the taper phase, physical activity in the no-rewards school continued to increase (+2030 steps per day, p < 0.001) but had returned to baseline in the full intervention school. The intervention that used only peer-modelling and pedometer goals produced better effects over time.

The effects of food-related attentional bias training on appetite and food intake

Obese and overweight individuals show a marked attentional bias to food cues. Food-related attentional bias may therefore play a causal role in over-eating. To test this possibility, the current study experimentally manipulated attentional bias towards food using a modified version of the visual probe task in which cake-stationery item image pairs were presented for 500 ms each. Participants (N=60) were either trained to attend to images of cake, trained to avoid images of cake, or assigned to a no-training control group. Hunger was measured before and after the training. Post-training, participants were given the opportunity to consume cake as well as a non-target food (crisps) that was not included in the training. There was weak evidence of an increase in attentional bias towards cake in the attend group only. We found no selective effects of the training on hunger or food intake, and little evidence for any gender differences. Our study suggests that attentional bias for food is particularly ingrained and difficult to modify. It also represents a first step towards elucidating the potential functional significance of food-related attentional biases and the lack of behavioural effects is broadly consistent with single-session attentional training studies from the addiction literature. An alternative hypothesis, that attentional bias represents a noncausal proxy for the motivational impact of appetitive stimuli, is considered.

Children's familiarity with snack foods changes expectations about fullness

BACKGROUND Palatability is regarded as a major determinant of childrens energy intake. However, few studies have considered nonhedonic beliefs about foods. In adults, there is emerging evidence that expectations about the satiating properties of foods are an important determinant of meal size, and these beliefs are learned. OBJECTIVE We measured and quantified childrens expected satiation across energy-dense snack foods by using a method of adjustment. Participants changed a comparison-food portion (pasta and tomato sauce) to match the satiation that they expected from a snack food. We predicted that children who were especially familiar with snack foods would expect the foods to generate greater satiation and that children who were unfamiliar with snack foods would match expected satiation on the basis of the physical characteristics (perceived volume) of the foods. DESIGN Seventy 11- to 12-y-old children completed measures of expected satiation, perceived volume, familiarity, and liking across 6 snack foods. RESULTS As anticipated, familiarity and expected satiation were positively related (r = 0.37, P = 0.002), and this association remained after liking was controlled for. Furthermore, expected-satiation and perceived-volume judgments were more dissimilar as familiarity with the foods increased. CONCLUSIONS Our findings highlight the role of learning in shaping childrens beliefs about the postingestive effects of the consumption of foods; children who ate the foods more often expected them to deliver greater satiation. Furthermore, our findings suggest that, in the absence of prior experience, children rely on a foods physical characteristics (a less-complex strategy) when they judge expected satiation. This trial was registered at clinicaltrials.gov as NCT01403753.

Eating under observation: a systematic review and meta-analysis of the effect that heightened awareness of observation has on laboratory measured energy intake

BACKGROUND Laboratory paradigms are commonly used to study human energy intake. However, the extent to which participants believe their eating behavior is being measured may affect energy intake and is a methodologic factor that has received little consideration. OBJECTIVE Our main objective was to examine available evidence for the effect that heightened awareness of observation has on energy intake in a laboratory setting. DESIGN We systematically reviewed laboratory studies that allowed for experimental examination of the effect that heightened awareness of observation has on energy intake. From these experimental studies we combined effect estimates using inverse variance meta-analysis, calculating the standardized mean difference (SMD) in energy intake between heightened-awareness and control conditions and qualitatively synthesized potential moderators of this effect. RESULTS Nine studies, providing 22 comparisons, were eligible for inclusion. These studies largely sampled young women and examined the energy intake of energy-dense snack foods. Evidence indicated that heightened awareness of observation was associated with reduced energy intake when compared with the control condition (random-effects SMD: 0.45; 95% CI: 0.25, 0.66; P < 0.0001). We found little evidence that the type of experimental manipulation used to heighten awareness moderated the overall effect. CONCLUSIONS The available evidence to date suggests that heightened awareness of observation reduces energy intake in a laboratory setting. These findings suggest that laboratory studies should attempt to minimize the degree to which participants are aware that their eating behavior is being measured.

Lack of association between DRD2 and OPRM1 genotypes and adiposity.

BACKGROUND:Dopaminergic and opioid systems are both involved in food intake and appetite control. The dopamine D2 receptor gene (DRD2) and the μ-opioid receptor gene (OPRM1) therefore represent plausible candidates for association with obesity.OBJECTIVE:Previous studies of these variants have yielded inconsistent findings, which are likely due to insufficient statistical power. The aim of the current study was to determine whether, in a large population-based sample, there are associations between adiposity and (i) the A1 (T) allele of the Taq1A polymorphism (rs1800497) in DRD2 and (ii) the G allele of the A118G polymorphism (rs1799971) in OPRM1.STUDY POPULATION:Annual clinic-based measures of body mass index (BMI) and waist circumference were taken from children (N=3720) at 5 measurement time points from ages 7 through to 11 years. BMI was also recorded in their mothers (N=2460) at comparable time points and at pre-pregnancy. All participants were genotyped. Our study was powered (at 80%) to detect per-allele effects on BMI of 0.21 kg m−2.RESULTS:Our results indicate a lack of association between DRD2 and OPRM1 genotypes and adiposity. Combining the data across mothers and children found per-allele effects on BMI of 0.02 kg m−2 (95% confidence interval (CI): −0.17, 0.20), P=0.9 for rs1800497 and −0.08 kg m−2 (95% CI: −0.29, 0.22), P=0.4 for rs1799971. As a positive control, we also examined the effect of FTO genotype over the same time period and confirmed the expected relationship between variability at this locus and higher adiposity.CONCLUSION:Our findings question existing evidence suggesting associations at DRD2 and OPRM1 loci and adiposity. They also highlight the caution required when employing candidate gene approaches to further our understanding of the neurobiology of eating and obesity.

Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies.

Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study 3 participants were exposed to images of large or small portions of a snack food before selecting a portion size of snack food to consume. Across the three studies, visual exposure to larger as opposed to smaller portion sizes resulted in participants considering a normal portion of food to be larger than a reference intermediate sized portion. In studies 1 and 2 visual exposure to larger portion sizes also increased the size of self-reported ideal meal size. In study 3 visual exposure to larger portion sizes of a snack food did not affect how much of that food participants subsequently served themselves and ate. Visual exposure to larger portion sizes may adjust visual perceptions of what constitutes a ‘normal’ sized portion. However, we did not find evidence that visual exposure to larger portions altered snack food intake.