Appetite 83 (2014) 256–262

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Appetite j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / a p p e t

Research report

Pre-meal video game playing and a glucose preload suppress food intake in normal weight boys ☆ Alyson Branton a, Tina Akhavan b, Branka Gladanac b, Damion Pollard a, Jo Welch c, Melissa Rossiter d, Nick Bellissimo b,* a Department of Applied Human Nutrition, Faculty of Professional Studies, Mount Saint Vincent University, 166 Bedford Highway, Halifax, Nova Scotia B3M 2J6, Canada b School of Nutrition, Ryerson University, 350 Victoria St, Toronto, Ontario M5B 2K3, Canada c Division of Kinesiology, School of Health and Human Performance, Dalhousie University, 6230 South St, Halifax, Nova Scotia B3H 4R2, Canada d Department of Applied Human Sciences, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island C1A 4P3, Canada

A R T I C L E

I N F O

Article history: Received 28 March 2014 Received in revised form 13 August 2014 Accepted 14 August 2014 Available online 20 August 2014 Keywords: Children Food intake Glucose preload Subjective appetite Subjective emotions Video game playing

A B S T R A C T

Increased food intake (FI) during television viewing has been reported in children, but it is unknown if this occurs following pre-meal video game playing (VGP). The objective was to determine the effect of pre-meal VGP for 30 min on subjective appetite and emotions, and FI in normal weight (NW) boys after a glucose or control preload. On four test mornings, NW boys (n = 19) received equally sweetened preloads of a non-caloric sucralose control or 50 g glucose in 250 mL of water, with or without VGP for 30 min. Food intake from an ad libitum pizza meal was measured immediately after. Subjective appetite was measured at 0, 15, 30, and 60 min. Subjective emotions were determined by visual analog scale at baseline and immediately before lunch. Both VGP (p = 0.023) and glucose (p < 0.001) suppressed FI. Pre-meal VGP compared with no-VGP, and glucose compared with the non-caloric control, decreased FI by 59 and 170 kcal, respectively. Subjective average appetite increased to 30 min (p = 0.003), but was lower after glucose (p = 0.01) in both the VGP and no-VGP conditions compared with the control. Frustration and aggression scores increased after VGP (p < 0.05), but did not correlate with FI. However, baseline and pre-meal happiness and excitement scores were inversely associated with FI. In conclusion, both pre-meal VGP and the glucose preload suppressed FI, supporting the roles of both physiologic and environmental factors in the regulation of short-term FI in 9- to 14-year-old NW boys. © 2014 Published by Elsevier Ltd.

Introduction Screen-time exposure is an etiological factor contributing to obesity in children (Shields, 2006), and thus current guidelines recommend limiting screen-time to less than 2 h per day in children and youth (Tremblay et al., 2011). Video game playing (VGP) is becoming an increasing contributor to total screen-time exposure in Canadian (Active Healthy Kids Canada, 2012) and American (Foehr

Abbreviations: FI, food intake; TVV, television viewing; VAS, visual analog scales; VGP, video game playing. ☆ Acknowledgments: This research was supported by the Danone Institute of Canada, Grant-in-Aid Program, and the Faculty of Community Services, Ryerson University publication grant to Nick Bellissimo. The authors would like to thank the parents and children enrolled in the study for their participation. The authors also appreciate the support from their volunteers: Brandon Gheller, Susan Gillespie, and Shulamite Sing. This trial was submitted to clinicaltrials.gov (NCT01750151). Competing interests: The authors declare that they have no competing interests. * Corresponding author. E-mail address: [email protected] (N. Bellissimo). http://dx.doi.org/10.1016/j.appet.2014.08.024 0195-6663/© 2014 Published by Elsevier Ltd.

et al., 2010) children who play an average of 1.9 and 1.2 h per day, respectively. While short-term food intake (FI) is regulated primarily by physiological signals (de Graaf et al., 2004), environmental factors (Bellisle et al., 2004) such as screen-based activities modify FI by reducing the efficacy of satiety signals arising from previously consumed food, which may accelerate the onset of the next meal and increase meal size. Few studies have directly measured the effect of screen exposure on the physiological regulation of FI in children (Bellissimo et al., 2007; Patel et al., 2011). In 9- to 14-year-old boys, television viewing (TVV) while eating contributed to a 24% greater energy intake and reduced satiety in response to a glucose preload consumed 30 min before a mixed-meal compared to the control (Bellissimo et al., 2007). In peripubertal girls, while FI was not increased due to TVV at mealtime, the reduction in FI after the glucose preload was only 1% during TVV compared with 22% without TVV (Patel et al., 2011). However, it is unknown if VGP has a similar impact on FI in children. Support for a source specific effect of screen-time exposure on FI is suggested from a recent study in adult women who had a lower

A. Branton et al./Appetite 83 (2014) 256–262

net surplus caloric intake after active gaming compared with TVV, or sedentary VGP (Lyons et al., 2012). Although observational studies suggest that most children (90%) eat occasionally during screentime (Moag-Stahlberg et al., 2003), food consumption does not typically coincide with concurrent VGP (Matheson et al., 2004). In older adolescents and young adults, pre-meal VGP and computer use increased next meal FI. For example, 15- to 19-year-old males, who played a 60 min video game, consumed a surplus of 80 kcal at a buffet meal compared with the control condition (Chaput et al., 2011). Similarly, in young women, ad libitum FI at a buffet meal that was preceded by 45 min of computerized tests exceeded the control condition by ~250 kcal (Chaput et al., 2008). However, neither study assessed the effect of a preload on FI, leaving uncertain whether VGP alters satiety signals from previously consumed foods. Therefore, we hypothesized that pre-meal VGP will increase FI and override the effect of a glucose preload in normal weight (NW) boys. The objective was to determine the effect of pre-meal VGP for 30 min after consumption of a glucose or non-caloric sucralose preload on subjective appetite and emotions, and FI in 9- to 14-year-old NW boys. Methods Participants Nineteen NW boys (between the 5th and 85th age- and sexspecific BMI percentile) (Ogden et al., 2002), 9 to 14 years of age, were recruited from advertisements in the local newspaper, library or community center, and by word-of-mouth (Table 1). To determine eligibility criteria, parents who volunteered their children completed a semi-structured telephone interview. Boys born at fullterm and normal birth weight were included, but those who were dieting, taking medication, and who had significant behavioral or emotional difficulties were excluded from the study. If the child met the initial study requirements, an appointment was made for the parent and child to attend a screening session at the Department of Applied Human Nutrition, Mount Saint Vincent University, Halifax, Nova Scotia where the study was explained to the parent and child. Informed written consent was provided by the parent and assent from the child. Anthropometric measurements of height (m), weight (kg), triceps, biceps, supra-iliac, and subscapular skinfold thickness (mm) were obtained using a Harpenden skinfold caliper and recorded to the nearest 0.1 mm. Estimates of percent body fat were calculated from a sex-specific regression equation using the sum of the four skinfold measurements (Brook, 1971), as described previously (Bellissimo et al., 2007, 2008). Study design and protocol A within-subject 2 × 2 repeated measures factorial design was used to examine the effect of VGP (VGP vs. no-VGP) and preload

Table 1 Baseline characteristics of participants.a Age (years) Body weight (kg) Height (m) BMI (kg/m2) BMI percentile Fat massb (%) Fat massb (kg) Fat-free mass (%) Fat-free mass (kg)

12.0 ± 0.5 44.1 ± 2.9 1.5 ± 3.6 18.7 ± 0.5 59.5 ± 5.3 21.3 ± 1.2 9.6 ± 0.9 78.7 ± 1.2 34.6 ± 2.2

Data are presented as means ± SEM, n = 19. Fat mass was determined from the sum of skinfold measurements at four points (Brook, 1971). a

b

257

(glucose vs. non-caloric control) on FI. Boys were randomly selected into a particular treatment order, which was counterbalanced. Girls were not included in this study because video game use is reported to be less frequent among girls compared with boys (Olson et al., 2007). The Research Ethics Review Board at Mount Saint Vincent University approved this study. On four separate mornings, 7 days apart, boys arrived at the Department of Applied Human Nutrition at 10:00 am, 11:00 am, or 12:00 pm, 2 h after consuming the standardized breakfast at home (8:00, 9:00, or 10:00 am). The standardized breakfast consisted of fat-free skim milk (Scotsburn®, 250 mL, 90 kcal, donated by Scotsburn® Dairy Group, Scotsburn, NS, Canada), breakfast cereal (Honey Nut Cheerios®, 26 g, 103 kcal) and orange juice (Tropicana Orange Juice®, 236 mL, 110 kcal; Tropicana Products Inc, Bradenton, FL, USA). As previously reported in our publications (Bellissimo et al., 2007, 2008; Patel et al., 2011), subjective appetite sensations were assessed by using the motivation-to-eat visual analog scales (VAS), and a physical comfort VAS, at 0 min (baseline) and at 15 min intervals before (15 and 30 min), and immediately after (60 min) the mixed-meal pizza lunch. Sweetness and pleasantness of the test preloads, pleasantness of the pizza lunch, subjective emotions, and enjoyment of the video game were also determined by VAS. Each VAS consisted of a 100 mm line anchored at the beginning and end by opposing statements. The participants marked an “X” on the line to indicate their feelings at that given moment. Scores were determined by measuring the distance (in mm) from the left starting point of the line to the intersection of the “X.” Sweetness and pleasantness VAS questionnaires were administered immediately after the preloads and test meal. Pleasantness of the preload and pizza meal also consisted of a 100 mm line anchored at the beginning and end by opposing statements as follows: “How pleasant have you found the preload/food? (“not pleasant at all” to “very pleasant”), while sweetness of the preload was assessed by “How sweet have you found the preload? (“not sweet at all” to “extremely sweet”). In our previous studies, we reported increased FI during TVV at mealtime in both boys (Bellissimo et al., 2007) and pre-pubertal girls (Patel et al., 2011); however, the mechanism of action remains unknown. Because changes in FI have been reported among adults who identify as emotional eaters (Oliver et al., 2000), we wanted to determine whether a change in subjective emotions was associated with altered FI in NW boys. There are no prior studies assessing the effect of subjective emotions on FI in children of any age, which was the basis for the measurement of subjective emotions in the current study. Therefore, to assess the emotional responses to VGP, VAS assessing subjective emotions were filled out by the children before and immediately following each experimental condition to 30 min. The subjective emotion screening VAS consisted of the following seven questions: (1) How aggressive do you feel? (“not aggressive at all” to “very aggressive”), (2) How angry do you feel? (“not angry at all” to “very angry”), (3) How excited do you feel? (“not excited at all” to “very excited”), (4) How disappointed do you feel? (“not disappointed at all” to “very disappointed”), (5) How happy do you feel? (“not happy at all” to “very happy”), (6) How upset do you feel? (“not upset at all” to “very upset”), (7) How frustrated do you feel? (“not frustrated at all” to “very frustrated”). Boys were given equally sweetened preloads of a non-caloric sucralose control (150 mg sucralose, Splenda; donated by Tate and Lyle, Decatur, IL, USA) or 50 g of glucose (54.6 g of glucose monohydrate; Grain Process Enterprises, Toronto, ON, Canada) in 250 mL of water. Sucralose was chosen because it is not metabolized in the body and does not alter blood glucose or insulin secretion (Duffy & Anderson, 1998). Aspartame-sweetened, orange-flavored crystals (1.1 g; Sugar Free Kool-Aid, Kraft Canada Inc., Don Mills, ON, Canada) were added to standardize the flavor of preloads. Preloads

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were prepared the evening before each test session in covered, opaque cups, and stored in the refrigerator until they were served to participants the following morning. Boys consumed the chilled preload, followed by 50 mL of water to minimize aftertaste, within 5 min. After consuming the preload, boys participated in either a nonscreen resting control condition (no-VGP) or VGP for 30 min. Immediately after the completion of each test session, boys were escorted into the sensory evaluation room and individually seated in their own cubicle, free of most external cues, and served an ad libitum pizza lunch along with a 500 mL bottle of water (Danone Crystal Springs) for 30 min until they were comfortably full. Boys were provided a hot tray of three small pizzas at the start of the meal period followed by additional trays served at 10 min intervals for 30 min. Based on pre-determined ranking of preference for two pizza varieties at the screening session, participants were served two pizzas of their first choice and one pizza of their second choice. The option of being served a single variety of three pizzas was only available if the children indicated a dislike for a particular variety, and the variety served was consistent at every session. Two varieties of Deep ‘N Delicious 5″ diameter pizza (averaging 180 kcal) were used; pepperoni and three-cheese pizzas (donated by McCain® Canada Ltd., Florenceville, NB, Canada). On average, each pizza weighed approximately 84 g, contained 9 g of protein, 6 g of fat, and 23 g of carbohydrate. The cooked pizzas were weighed and cut into four equal pieces before serving, and the amount left after the meal was subtracted from the initial weight to determine the net weight consumed in grams. The net weight consumed (g) was then converted to kcal using information provided by the manufacturer to provide a measure of FI. The bottled water was weighed before and after the meal to calculate the net amount consumed in grams. After the pizza meal, boys completed VAS questionnaires assessing their motivation-to-eat and physical comfort.

Video game playing protocol During each of the two VGP conditions, boys played the video game Angry Birds (Rovio Entertainment Inc.) on a PlayStation®3 (Sony Computer Entertainment Inc.) that was displayed on a large projector screen for 30 min. Boys played the game individually, in separate rooms from other children, in order to eliminate the possibility of being distracted or competition developing among them. During the screening visit, each child was given a tutorial on how to operate the game console and play the game. Angry Birds was selected for use in this study because it is easy to learn, provides continuous engagement, and at the time was popular among children and adolescents in our age range. Only after the two VGP conditions, children completed a VGP acceptability VAS to assess their enjoyment of the video game with the following question: “How well did you enjoy the video game?” (“did not enjoy at all” to “enjoyed very much”).

Statistical analysis Food and water intakes, and subjective measures of preload sweetness, and pleasantness of the preload and pizza were analyzed using a within-subject repeated measures two-way ANOVA using the PROC MIXED procedure (9.2 SAS Institute Inc., Cary, NC, USA), with preload (control and glucose) and VGP (no-VGP and VGP) as main factors. Subjective appetite, physical comfort, and subjective emotions were analyzed as the change from baseline using a within-subject repeated measures three-way ANOVA using the PROC MIXED procedure (9.2 SAS Institute Inc.) with time, preload, and VGP as main factors. Post hoc analysis by the Tukey–Kramer test, adjusted for multiple comparisons, was performed when treatment effects were found to be statistically significant. Student’s paired t-tests were used to compare caloric compensation scores and VGP enjoyment. Statistical significance was defined at p < 0.05. Correlations on dependent measures were conducted using Pearson correlation coefficients (9.2 SAS Institute Inc.). An average appetite score was calculated at each time of measurement for each treatment using the following formula: Average Appetite score (mm) = [desire-to-eat + hunger + (100 − fullness) + prospective food consumption]/4, which reflects the four questions of the motivation-to-eat VAS (Bellissimo et al., 2007, 2008). Cumulative energy intake (kcal) was calculated by adding together FI consumed at the test meal and the energy content of the preload. Caloric compensation was calculated for each individual with the following formula: Caloric compensation (%) = [(FI after the non-caloric sucralose control preload (kcal) – FI after the glucose preload (kcal))/kcal in the glucose preload] × 100 (Bellissimo et al., 2007, 2008). Results Participants Nineteen normal weight boys (between the 5th and 85th ageand sex-specific BMI percentile) with a mean age of 12.0 ± 0.5 years participated in this study and completed all four experimental test sessions (Table 1). Food intake, caloric compensation and water intake Food intake was affected by preload (p < 0.0001) and VGP (p = 0.023), but there was no preload by VGP interaction (p = 0.13). Glucose, compared to the non-caloric preload, reduced FI by 170 kcal, and VGP reduced FI at the test meal by 59 kcal (Table 2). Cumulative energy intake [meal (kcal) plus preload (kcal)] was lower after VGP than after no-VGP (p = 0.02), but there was no significant preload (p = 0.22) or VGP by preload interaction (p = 0.13) (Table 2). Caloric compensation scores after glucose in the VGP condition (66 ± 18%) was lower than glucose after no-VGP (104 ± 17%), but this difference was not statistically significant (p = 0.13). Water intake was not affected by the preload (p = 0.22), or VGP (p = 0.67) and there was no preload by VGP interaction (p = 0.08) (Table 2).

No-video game playing protocol

Subjective appetite and emotions

During each of the two 30 min no-VGP conditions, boys were seated comfortably while they engaged in conversation with each other and the research volunteers. Children did not have access to screens such as televisions, computers, or cell phones and were restricted from participating in any mentally stimulating activities like board games and trivia because those activities may affect FI (Chaput et al., 2008). Research volunteers supervised the children at all times, and redirected any discussions related to food.

Change from baseline average appetite, hunger, fullness and prospective food consumption were affected by time (p < 0.05) and preload (p < 0.05) in the pre-meal period (0–30 min), but not by VGP (average appetite: p = 0.64; hunger: p = 0.83; fullness: p = 0.17; prospective food consumption: p = 0.88) (Fig. 1). Change from baseline desire-to-eat scores increased to 30 min (p = 0.01) but were not affected by preload treatment (p = 0.42) or VGP (p = 0.69). Glucose led to significantly lower average appetite (p = 0.01), hunger (p = 0.01),

A. Branton et al./Appetite 83 (2014) 256–262

Table 2 Effect of preload and video-game playing on food intake, cumulative energy intake, caloric compensation and water intake.a No-VGP

Food intakeb (kcal) Cumulative energy intakec (kcal) Caloric compensationd (%) Water intakee (g)

VGP

Control

Glucose

Control

Glucose

977 ± 54 977 ± 54

770 ± 69 970 ± 69

881 ± 67 881 ± 67

749 ± 65 949 ± 65

203 ± 35

104 ± 17 215 ± 39

233 ± 41

66 ± 18 166 ± 32

Data are means ± SEM; n = 19. Food intake at a pizza meal 30 min after preload (control or glucose) and screen exposure (VGP or no-VGP). Food intake was affected by preload (p < 0.0001) and VGP (p = 0.02), but there was no preload by VGP interaction (p = 0.13). c Cumulative Energy Intake = preload kcal + FI from test meal kcal. Cumulative energy intake was affected by VGP (p = 0.02), but not preload (p = 0.22), and there was no preload by VGP interaction (p = 0.13). d Caloric compensation = [(kcal consumed at the test meal after control preload – kcal consumed at the test meal after glucose preload)/(kcal in glucose preload] × 100%. Caloric compensation was not affected by preload (p = 0.13). e Water consumed at the pizza meal 30 min after test conditions Water intake was not affected by preload (p = 0.22), or VGP (p = 0.67), and there was no preload by VGP interaction (p = 0.08). a

b

and prospective food consumption scores (p = 0.02) and higher fullness scores (p = 0.01) immediately before the test meal compared with the sucralose control preload. There were no significant interactions among time, preload, and VGP. Only aggression (p = 0.05) and frustration (p < 0.05) scores increased after VGP compared to no-VGP; however, anger (p = 0.87), disappointment (p = 0.21), excitement (p = 0.65), happiness (p = 0.76), and upset (p = 0.21) did not (Fig. 2). Aggression (p = 0.88), anger (p = 0.84), disappointment (p = 0.99), excitement (p = 0.39), frustration (p = 0.71), happiness (p = 0.69), and upset (p = 0.40) were not affected by preload and there were no significant preload by VGP interactions. Subjective ratings of physical comfort, sweetness, pleasantness, and enjoyment of the video game Physical comfort scores were not affected by preload (p = 0.20) or VGP (p = 0.09), and there was no significant preload by VGP interaction (p = 0.43). Preload sweetness (p = 0.04) and pleasantness (p < 0.0001) were affected by the preload, but VGP was not a factor affecting preload sweetness (p = 0.89) or pleasantness (p = 0.40) (Table 3). Children rated the sucralose control preload sweeter and less pleasant than the glucose solution. Pleasantness of the pizza meal was not affected by preload (p = 0.46) or VGP (p = 0.48) (Table 3). The video game was rated as enjoyable (control, t = 80 ± 5 mm; glucose, t = 81 ± 5 mm) and did not differ between test conditions (Student’s paired t-test: p = 0.51) (Table 3). Associations between subjective average appetite and food intake Average appetite scores did not correlate with FI at any of the measured time points after any of the treatment conditions. Of the individual appetite scores, only desire-to-eat and hunger were inversely correlated with FI at baseline in the glucose (VGP) condition (desire-to-eat: r = −0.57, p = 0.011; hunger: r = −0.52, p = 0.02). Associations between subjective emotions and food intake Subjective excitement scores at baseline (0 min) and 30 min were inversely associated with FI after the glucose preload in the no-VGP condition (baseline: r = −0.64, p = 0.003; 30 min: r = −0.62, p = 0.005) and the sucralose control preload in the VGP condition (baseline: r = −50, p = 0.03; 30 min: r = −0.47, p = 0.04). Subjective hap-

259

piness scores at baseline were inversely associated with FI after the sucralose preload in the no-VGP condition (r = −0.59, p = 0.007), and the glucose preload in the VGP condition (r = −0.47, p = 0.04). Subjective happiness at 30 min was inversely correlated with FI after the glucose preload in the no-VGP condition (r = −0.47, p = 0.04), and the sucralose control preload in the VGP condition (r = −0.46, p = 0.05). Relationships between body composition and food intake Body weight (kg) was positively associated with FI after the control and glucose preloads in both the no-VGP (control: r = 0.78, p < 0.0001; glucose: r = 0.81, p < 0.0001) and VGP (control: r = 0.71, p < 0.001; glucose: r = 0.80, p < 0.0001) conditions. Fat mass (kg) was positively associated with FI after the sucralose control and glucose preloads in both the no-VGP (control: r = 0.60, p < 0.01; glucose: r = 0.60, p < 0.01) and VGP (control: r = 0.48, p < 0.05; glucose: r = 0.54, p < 0.05) conditions. Fat-free mass (kg) was positively associated with FI after the sucralose control and glucose preloads in both the noVGP (control: r = 0.79, p < 0.0001; glucose: r = 0.82, p < 0.0001) and VGP (control: r = 0.73, p < 0.001; glucose: r = 0.83, p < 0.0001) conditions. The glucose preload expressed on a BW basis (g/kg) was inversely associated with FI after the VGP (r = −0.79, p < 0.0001) and no-VGP (r = −0.77, p < 0.0001) conditions, suggesting that boys who received a smaller treatment dose relative to body weight consumed more calories at the test meal. Discussion The results of this study did not support the hypothesis that premeal VGP increases FI and overrides the effect of a glucose preload in NW boys. Food intake was lower after VGP compared with noVGP, and after the glucose preload compared with the sucralose control. To our knowledge, these results are first to report lower FI at a test meal immediately after VGP. In the only other published study, FI from snack and lunch consumed during TVV were lower compared with the no-TVV condition, in 3- to 5-year-old preschool children (Francis & Birch, 2006), which was attributed to preoccupation with TVV, and the consequential diversion of attention away from eating. Thus, our findings are unique because this is the only study to examine the effect of pre-meal VGP on FI in children, suggesting that the modest suppression of FI that occurs after VGP persists in the absence of concurrent eating and VGP. To assess whether VGP prior to mealtime alters FI in response to previously consumed calories, we utilized a preload design. Food intake was reduced by an amount similar to its caloric content, which is consistent with previous studies in NW men (Anderson et al., 2002) and our studies in children (Bellissimo et al., 2007, 2008). Boys compensated fully for the energy content of the glucose preload during the no-VGP test condition, adding to a body of evidence that children accurately adjust for the energy content of sugars in solution by decreasing FI at their next meal (Bellissimo et al., 2007, 2008; Birch & Deysher, 1986). Although boys only partially compensated for the glucose preload (66%) after VGP, this observation is not indicative of an attenuated response to the glucose preload. Rather, it reflects the greater decrease in FI after the control preload compared to the glucose load during VGP. Food intake was ~10% and ~3% lower after the sucralose and glucose preloads, respectively, in the VGP conditions compared with their respective control conditions. In contrast to these results, TVV during mealtime diminished satiety signals from a glucose preload in both 9- to 14year-old boys (Bellissimo et al., 2007) and peripubertal girls (Patel et al., 2011). Nevertheless, a reduction in FI of approximately 59 kcal after VGP in these 9- to 14-year-old boys is in contrast to the only

A. Branton et al./Appetite 83 (2014) 256–262

40

40

30

30

Desire-to-Eat (mm)

Average Appetite (mm)

260

20

10

0

-10

10

0

-10

0

10

20

30

40

30

30

20

20

10

Fullness (mm)

Hunger (mm)

20

10

0

0

10

20

30

0

10

20

30

0

-10

-20

-10

0

10

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30

Prospective Food Consumption (mm)

40

30

20

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0

-10

0

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30

Fig. 1. Effect of video game playing and preload treatment on subjective appetite scores. Average and individuals appetite scores changed over time (p < 0.05) for (A) average appetite, (B) desire-to-eat, (C) hunger, (D) fullness, and (E) prospective food consumption. Subjective average appetite (p = 0.01), hunger (p = 0.01), and prospective food consumption (p = 0.02) were lower, and fullness higher (p = 0.01) after glucose, but did not affect desire-to-eat (p = 0.42). Video game playing did not affect change from baseline average appetite (p = 0.64), desire-to-eat (p = 0.69), hunger (p = 0.83), fullness (p = 0.17), or prospective food consumption (p = 0.88), and there were no significant interactions. Arrows represent initiation of test meal at 30 min. VGP, video game playing.

A. Branton et al./Appetite 83 (2014) 256–262

20

Frustration (mm)

20

Aggression (mm)

261

10

0

10

0

-10 0

10

20

30

0

10

20

30

Fig. 2. Effect of video game playing and preloads on subjective emotions. Change from baseline emotional scores for (A) aggression, and (B) frustration from 0 to 30 min during treatment conditions. Aggression and frustration scores increased from baseline to 30 min during VGP (p < 0.05). Arrows represent initiation of test meal at 30 min. VGP, video game playing.

other report of FI after VGP in 15- to 19-year-old adolescents and young adults (Chaput et al., 2011). In the aforementioned study, higher FI was reported in older male adolescents at a lunchtime meal offered 10 min after a 60-min session of playing a soccer video game compared to sitting. Computerized activities are thought to influence FI through their effect on brain glucose utilization, which may increase later FI (Chaput et al., 2008). In young women, mental work was associated with glucose instability, and was accompanied by a subsequent increase in FI (Chaput et al., 2008), with a more pronounced effect when the cognitive demand of the task increased (Chaput & Tremblay, 2009). However, men who completed a similar mental task consumed fewer calories at an ad libitum lunch compared to resting (Perusse-Lachance et al., 2013), and therefore, sex differences, and individual differences in perceived workload may be factors affecting the eating response to mental work. Pre-meal subjective happiness and excitement scores were inversely associated with FI suggesting that higher positive affect at baseline contributed to decreased meal-time FI. Because no other

Table 3 Effect of preload treatment and video-game playing on subjective sensory ratings and enjoyment of the video game.a No-VGP

Sweetness (preload)b (mm) Pleasantness (preload)c (mm) Pleasantness (test meal)d (mm) Video game enjoymente (mm)

VGP

Control

Glucose

Control

Glucose

81 ± 4 39 ± 6

76 ± 3 55 ± 6

82 ± 4 28 ± 6

76 ± 5 58 ± 6

78 ± 5

74 ± 5

74 ± 5

73 ± 5

–

–

80 ± 5

81 ± 5

Data are means ± SEM; n = 19. Preload sweetness was affected by preload (p = 0.04) but not by VGP (p = 0.98). c Pleasantness of the preload was affected by preload (p < 0.0001), but not by VGP (p = 0.40). d Pleasantness of the pizza meal was not affected by preload (p = 0.46) or VGP (p = 0.48). e Enjoyment of the video game was not affected by preload (p = 0.51). a

b

subjective emotion scores correlated with FI, our results suggest that boys were susceptible to eating less often during states of positive, but not negative affect. This is consistent with previous findings of the eating response to positive emotions, which is a distinct construct from the eating response to negative emotions (Nolan et al., 2010; van Strien et al., 2013). Overeating in response to states of negative affect and stress is a coping mechanism (Timmerman & Acton, 2001) often observed in individuals susceptible to emotional eating (Macht, 2008), but less is known on how positive emotions affect FI. In a recent study, women who were assigned to watch a comedy clip consumed 54 fewer kcal from a later snack than those who watched a neutral-mood video clip; however, decreased FI from positive emotions was limited to individuals who were controlled eaters (Turner et al., 2010). An explanation for decreased FI may be due to the “broaden-and-build” theory, which suggests that individuals who experience positive emotions have a greater capability to cope with challenges (Fredrickson, 2001), such as the ability to resist palatable food (Evers et al., 2013). Similar to our previous studies in children (Bellissimo et al., 2007, 2008), boys in this study reported a decrease in average appetite, after the pizza meal, which confirms that they understood the VAS and were able to express their motivation to eat. Although the decrease in subjective appetite after the glucose preload resulted in lower FI at the test meal, there were no significant associations between subjective average appetite scores or post-baseline individual appetite scores and FI at any of the measurement time points. In our previous studies, we reported significant associations between subjective appetite and FI in boys (Bellissimo et al., 2007) and postpubertal girls (Patel et al., 2011), and therefore, the lack of association in the present study may have been due to the small sample size. Sensory-hedonic differences between the preloads were not factors explaining FI. Altered FI due to differences in sweetness and pleasantness are known to affect FI in adults (Sorensen et al., 2003), but it is unknown how the interaction between lower sweetness and increased pleasantness of the glucose preload affected later FI. Our results suggest an uncoupling of the effect of sensory-hedonic ratings on FI due to the lack of association between sweetness or pleasantness and FI, suggesting that post-ingestive factors from the glucose preload and VGP were the primary determinant of FI.

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Our results challenge the view that all screen-time exposure is a risk factor for overeating in children. The decrease in FI after VGP offers new evidence that VGP differs from other screen-time activities in its effect on eating behavior and thus, there may be a need for screen-specific recommendations in children as it relates to the maintenance of healthier body weights. Future studies investigating the effect of VGP on FI and energy balance is warranted, especially in girls, overweight and obese children, and emotional eaters. Conclusion Both pre-meal VGP and the glucose preload suppressed FI, supporting the roles of both physiologic and environmental factors in the regulation of short-term FI in 9- to 14-year-old NW boys. Authors’ contributions AB coordinated and executed the study, performed all statistical analyses, and drafted the manuscript. TA contributed to the interpretation of the findings, and helped to draft the manuscript. DP assisted with participant recruitment and data acquisition. BG, JW, and MR contributed to drafting the manuscript. NB conceived of the study, supervised AB, and directed drafting of the manuscript. All authors read and approved the final manuscript. References Active Healthy Kids Canada (2012). Is active play extinct? The 2012 active healthy kids Canada report card on physical activity for children and youth. Toronto: Active Healthy Kids Canada. www.activehealthykids.ca pp. 1–106. Anderson, G. H., Catherine, N. L., et al. (2002). Inverse association between the effect of carbohydrates on blood glucose and subsequent short-term food intake in young men. The American Journal of Clinical Nutrition, 76(5), 1023–1030. Bellisle, F., Dalix, A. M., et al. (2004). Non food-related environmental stimuli induce increased meal intake in healthy women. Comparison of television viewing versus listening to a recorded story in laboratory settings. Appetite, 43(2), 175–180. Bellissimo, N., Desantadina, M. V., et al. (2008). A comparison of short-term appetite and energy intakes in normal weight and obese boys following glucose and whey-protein drinks. International Journal of Obesity (2005), 32(2), 362–371. Bellissimo, N., Pencharz, P. B., et al. (2007). Effect of television viewing at mealtime on food intake after a glucose preload in boys. Pediatric Research, 61(6), 745–749. Bellissimo, N., Thomas, S. G., et al. (2007). Effect of short-duration physical activity and ventilation threshold on subjective appetite and short-term energy intake in boys. Appetite, 49(3), 644–651. Birch, L. L., & Deysher, M. (1986). Caloric compensation and sensory specific satiety. Evidence for self regulation of food intake by young children. Appetite, 7(4), 323–331. Brook, C. G. (1971). Determination of body composition of children from skinfold measurements. Archives of Disease in Childhood, 46(246), 182–184. Chaput, J. P., Drapeau, V., et al. (2008). Glycemic instability and spontaneous energy intake. Association with knowledge-based work. Psychosomatic Medicine, 70(7), 797–804.

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