Association between screen time and accelerometer-measured 24-h movement behaviors in a sample of Brazilian adolescents.

OBJECTIVES: Different screen time activities may be related to sleep, physical activity, and sedentary behavior. The objective was to examine the association between self-reported screen time activities and accelerometer-measured 24-h movement behaviors. STUDY DESIGN: This was a cross-sectional study. METHODS: Adolescents' (n = 718, 50.4% girls, 16 years) sleep duration, sedentary behavior, light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) were estimated with wrist-worn accelerometry. Time spent on screen time activities related to studying, working, watching videos, playing video games, and using social media was self-reported. Multilevel linear regressions were used to test the association between screen time with sleep, sedentary behavior, and physical activity. RESULTS: Boys and girls slept 6.4 and 6.7 h per night, spent 10.4 and 10.1 h/d in sedentary behavior, spent 4.0 and 4.4 h/d in LPA, and spent 34.7 and 29.2 min/d in MVPA, respectively. Studying was inversely related to LPA and MVPA. Working was inversely related to sleep and positively related to LPA. Watching videos was associated with lower LPA and MVPA. For boys, videogames were associated with increased sedentary behavior and lower LPA and MVPA. For girls, studying and/or using social media were associated with lower LPA and MVPA. CONCLUSIONS: Indicators of screen time were associated with different accelerometer-measured 24-h movement behaviors in this sample of Brazilian adolescents.

Adherence to 24-hour movement guidelines and academic performance in adolescents.

OBJECTIVE: The aim of the study was to examine the association between meeting combinations of the Canadian 24-h movement guidelines and academic performance in adolescents. STUDY DESIGN: This cross-sectional study used the 2017 Ontario Student Drug Use and Health Survey, a survey representative of Ontario students in grades 7-12 attending publicly funded schools. A total of 10,160 students were included in the analysis. METHODS: Moderate to vigorous physical activity (MVPA), screen time, sleep duration, and academic performance were self-reported. A multiple linear regression model was used to examine differences in academic performance between adolescents meeting and those not meeting the combinations of movement guidelines (≥60 min/day of MVPA; ≤2 h/day of screen time; 9-11 h/night of sleep for ages 11-13 years, 8-10 h/night for ages 14-17 years, and 7-9 h/night for ages 18 years or older). Covariates included age, sex, ethnicity, subjective socio-economic status, body mass index z-score, and substance use. RESULTS: We found that 5.1% of students met all three movement guidelines, whereas 39.0% did not meet any. Middle school students who met all three guidelines or either the screen time or sleep guideline displayed better academic performance than those who met none of the guidelines. High school students who met the screen time and sleep guidelines displayed better academic performance than those who did not meet any guidelines. CONCLUSIONS: Adhering to screen time and sleep duration recommendations is associated with better academic performance among adolescents.

Association of eating behaviour with clock gene polymorphism 3111 T > C in children based on nutritional status.

Background: The CLOCK (circadian locomotor output cycle kaput) gene is a central regulator of circadian rhythm. The CLOCK gene has been related to energy intake and therefore to nutritional status. However, its specific associations with aspects of food behaviour in children have been scarcely investigated.Aim: To determine the association between the CLOCK gene polymorphism 3111 T > C and eating behaviours in children based on nutritional status.Methods: A cross-sectional study of the association between a CLOCK gene variant and eating behaviour in children (n = 256) was performed. Eating behaviour was evaluated by the Child Eating Behaviour Questionnaire (CEBQ). In addition, the genotype of the CLOCK 3111 T > C (TT, CC, TC) gene polymorphism and BMI were determined.Results: The obese carriers of the C allele of the polymorphism had lower scores in the dimensions "response to satiety" and "slowness to eat" (p < 0.001), both of which constitute an anti-intake dimension and are related to food satiety.Conclusions: The C allele CLOCK gene could be considered a genetic risk factor for satiety-altered eating behaviour dimensions.

Cognitive restriction accentuates the increased energy intake response to a 10-month multidisciplinary weight loss program in adolescents with obesity.

BACKGROUND: Multidisciplinary interventions have shown some merits in weight reduction strategies in youth, however, their impact on subsequent daily energy intake remains largely unknown. The aim of the present study was to evaluate the nutritional responses to a 10-month multidisciplinary intervention among adolescents with obesity, in relation to their eating behavior characteristics. METHODS: Thirty-five adolescents (mean age: 13.4 ±â€¯1.2 years) with obesity took part in a 10-month residential multidisciplinary weight loss program. Anthropometric measurements, body composition (dual-energy X-ray absorptiometry), 24-h ad libitum energy intake (weighted), eating behaviors (Dutch Eating Behavior Questionnaire) and appetite sensations (Visual Analogue Scales) were assessed on three occasions: at their arrival in the institution (T0), after 5 months (T1), and at the end of the 10-month program (T2). RESULTS: The mean weight loss reached 11% of the adolescents' initial body weight, with an important inter-individual variability (-25% to +3% of their initial body weight). Results revealed sex differences change, with boys showing a higher decrease in fat mass percent and increase in fat-free mass compared with girls. Weight loss was accompanied by a significant decrease in emotional (-8.3%, p < 0.05) and external (-14.8%, p < 0.001) eating scores and a significant increase in 24-h ad libitum energy intake (+246 kcal, p < 0.001). The observed subsequent increased 24-h ad libitum energy intake at T2 compared to T0 was significantly higher in cognitively restrained eaters (+492 kcal) compared to unrestrained eaters (+115 kcal, p = 0,015). Dietary restraint score at baseline was inversely correlated with the percentage of weight loss (r = -0.44, p = 0.010). CONCLUSION: A 10-month multidisciplinary weight loss intervention induced an increase in 24-h ad libitum energy intake compared to baseline, especially in cognitively restrained eaters. Moreover, initially cognitively restrained eaters tended to lose less body weight compared to unrestrained ones. These findings suggest that cognitive restriction may be a useful eating behavior characteristic to consider as a screening tool for identifying adverse responders to weight loss interventions in youth.

Sources of variability in childhood obesity indicators and related behaviors.

The purpose of this study was to describe sources of variability in obesity-related variables in 6022 children aged 9-11 years from 12 countries. The study design involved recruitment of students, nested within schools, which were nested within study sites. Height, weight and waist circumference (WC) were measured and body mass index (BMI) was calculated; sleep duration and total and in-school moderate-to-vigorous physical activity (MVPA) and sedentary time were measured by accelerometry; and diet scores were obtained by questionnaire. Variance in most variables was largely explained at the student level: BMI (91.9%), WC (93.5%), sleep (75.3%), MVPA (72.5%), sedentary time (76.9%), healthy diet score (88.3%), unhealthy diet score (66.2%), with the exception of in-school MVPA (53.8%) and in-school sedentary time (25.1%). Variance explained at the school level ranged from 3.3% for BMI to 29.8% for in-school MVPA, and variance explained at the site level ranged from 3.2% for WC to 54.2% for in-school sedentary time. In general, more variance was explained at the school and site levels for behaviors than for anthropometric traits. Given the variance in obesity-related behaviors in primary school children explained at school and site levels, interventions that target policy and environmental changes may enhance obesity intervention efforts.

Perceptions and attitudes about body weight and adherence to the physical activity recommendation among adolescents: the moderating role of body mass index.

OBJECTIVE: We examined the associations between perceptions and attitudes about body weight and adherence to the physical activity recommendation (PAR) for adolescents to achieve ≥60 min/day of moderate-to-vigorous physical activity and tested whether body mass index (BMI) was a moderator of these relationships. STUDY DESIGN: Cross-sectional survey. METHODS: Self-reported data from Canadian adolescents (n = 4299) who participated in the 2013 Ontario Student Drug Use and Health Survey were analysed. RESULTS: Dissatisfaction with body weight was associated with lower odds of adherence to the PAR (odds ratio [OR]: 0.74; 95% confidence interval [CI]: 0.55-0.99). More specifically, those who perceived themselves as overweight/obese had lower odds of adherence to the PAR (OR: 0.59; 95% CI: 0.42-0.81) compared with those who think they were about the right weight. Those who were trying to gain weight were more likely to adhere to the PAR (OR: 1.92; 95% CI: 1.29-2.86) compared to those who were doing nothing about their body weight. BMI was a significant moderator of the association between dissatisfaction with body weight and adherence to the PAR. At low BMI, there were no differences in the adherence to the PAR between adolescents who were dissatisfied with their body weight or not. At high BMI, adolescents who were dissatisfied with their body weight were less likely to adhere to the PAR than those who were not dissatisfied with their weight. Results were not different between males and females. CONCLUSIONS: Results suggest that adolescents who are dissatisfied with their body weight have lower adherence to the PAR, particularly those who are overweight or obese.

Associations between meeting combinations of 24-h movement guidelines and health-related quality of life in children from 12 countries.

OBJECTIVES: To examine whether meeting vs not meeting movement/non-movement guidelines (moderate-to-vigorous physical activity [MVPA], screen time, sleep duration), and combinations of these recommendations, are associated with health-related quality of life (HRQoL) in children from 12 countries in five major geographic regions of the world and explore whether the associations vary by study site. STUDY DESIGN: Observational, multinational cross-sectional study. METHODS: This study included 6106 children aged 9-11 years from sites in Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom, and the United States. Participants completed the KIDSCREEN-10 to provide a global measure of their HRQoL. Sleep duration and MVPA were assessed using 24-h accelerometry. Screen time was assessed through self-report. Meeting the recommendations was defined as ≥60 min/day for MVPA, ≤2 h/day for screen time, and between 9 and 11 h/night for sleep duration. Age, sex, highest parental education, unhealthy diet pattern score, and body mass index z-score were included as covariates in statistical models. RESULTS: In the full sample, children meeting the screen time recommendation, the screen time + sleep recommendation, and all three recommendations had significantly better HRQoL than children not meeting any of these guidelines. Differences in HRQoL scores between sites were also found within combinations of movement/non-movement behaviors. For example, while children in Australia, Canada, and USA self-reported better HRQoL when meeting all three recommendations, children in Kenya and Portugal reported significantly lower HRQoL when meeting all three recommendations (relative to not meeting any). CONCLUSIONS: Self-reported HRQoL is generally higher when children meet established movement/non-movement recommendations. However, differences between study sites also suggest that interventions aimed at improving lifestyle behaviors and HRQoL should be locally and culturally adapted.

Comparison of ActiGraph GT3X+ and Actical accelerometer data in 9-11-year-old Canadian children.

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Food intake response to exercise and active video gaming in adolescents: effect of weight status.

Although a few data are available regarding the impact of video games on energy intake (EI) in lean adolescents, there is no evidence on the effect of passive and active video gaming on food intake in both lean and obese youth. It is also unknown whether isoenergetic active video games and exercise differently affect food consumption in youth. In all, twelve lean and twelve obese adolescent boys (12-15 years old) had to complete four 1-h sessions in a cross-over design study: control (CON; sitting), passive video game (PVG; boxing game on Xbox 360), active video game (AVG; boxing game on Xbox Kinect 360) and exercise (EX; cycling). The exercise and active video game activities were designed to generate the same energy expenditure (EE). EE was measured using a K4b2 portable indirect calorimeter. Ad libitum food intake and appetite sensations were assessed following the sessions. AVG and EX-EE were significantly higher in obese participants and significantly higher compared with PVG and CON in both groups. Obese participants significantly ate more than lean ones in all four conditions (P<0·001). EI did not differ between conditions in obese participants (CON: 4935 (SD 1490) kJ; PVG: 4902 (SD 1307) kJ; AVG: 4728 (SD 1358) kJ; EX: 4643 (SD 1335) kJ), and was significantly lower in lean participants after EX (2847 (SD 577) kJ) compared with PVG (3580 (SD 863) kJ) and AVG (3485 (SD 643) kJ) (P<0·05). Macronutrient intake was not significantly different between the groups or conditions. Hunger was significantly higher and satiety was lower in obese participants but no condition effect was observed. Overall, moderate-intensity exercise provides better effect on energy balance than an isoenergetic hour of active video gaming in lean adolescent boys by dually affecting EE and EI.

Use of social networking sites and alcohol consumption among adolescents.

OBJECTIVES: Research indicates that screen time (e.g. TV viewing) is associated with alcohol consumption in adolescents; however, very little is known about the link between the use of social networking sites (SNSs) and alcohol intake in this age group. The purpose of this study was to examine the association between the use of SNSs and alcohol consumption among Canadian middle and high school students, and to test whether this link varies by sex and drinking frequency or intensity. STUDY DESIGN: School-based cross-sectional study. METHODS: Self-reported data on time spent on SNSs, alcohol consumption and sociodemographic characteristics were obtained from 10,072 participants within the 2013 cycle of the Ontario Student Drug Use and Health Survey, a province-wide survey of students in grades 7-12 (11-20 years old). RESULTS: Adolescent females who reported daily use of SNSs (≤2 hours/day or >2 hours/day) were more likely than those who use them infrequently or do not use them at all to report both occasional and regular alcohol consumption in the past 12 months, while adolescent males who reported daily use of SNSs were more likely than those who use SNSs infrequently or do not use them at all to report regular alcohol use in the past 12 months. The use of SNSs was also associated with report of binge drinking (defined as drinking five or more drinks on one occasion) in the past 4 weeks in both males and females. CONCLUSIONS: Results provide evidence that the use of SNSs is associated with alcohol consumption among adolescents. Differences between males and females in the reported associations warrant further investigations.

Short sleep duration and large variability in sleep duration are independently associated with dietary risk factors for obesity in Danish school children.

BACKGROUND: Lack of sleep and increased consumption of energy-dense foods and sugar-sweetened beverages (SSBs) have all been suggested as factors contributing to the increased prevalence of overweight and obesity. OBJECTIVE: To evaluate whether objectively measured sleep duration (average and day-to-day variability) as well as parent-reported sleep problems are independently associated with proposed dietary risk factors for overweight and obesity in 8-11-year-old children. DESIGN: In this cross-sectional study, data on sleep duration and day-to-day variability in sleep duration were measured in 676 Danish, apparently healthy children by an objective measure (actigraphy) for 8 nights, and the Children's Sleep Habits Questionnaire (CSHQ) was filled out by the parents. Diet was recorded using a web-based food record for 7 consecutive days. Fasting blood samples were obtained for measurements of plasma leptin and ghrelin levels. RESULTS: Sleep duration (h per night) was negatively associated with energy density (ED) of the diet (ß = -0.32 kJ g(-1)), added sugar (ß = -1.50 E%) and SSBs (ß = -1.07 E%) (all P ≤ 0.003). Furthermore, variability in sleep duration (10-min per night) was positively associated with SSBs (ß = 0.20 E%, P = 0.03), independent of sleep duration, and CSHQ score was positively associated with ED (ß = 0.16 kJ g(-1), P = 0.04). All of these associations were independent of potential confounders (age, sex, pubertal status, height, weight, screen time, moderate-to-vigorous physical activity and parental education and ethnicity). CONCLUSION: Our study suggests that short sleep duration, high sleep duration variability and experiencing sleep problems are all associated with a poor, obesity-promoting diet in children.

Fatness predicts decreased physical activity and increased sedentary time, but not vice versa: support from a longitudinal study in 8- to 11-year-old children.

OBJECTIVE: To examine independent and combined cross-sectional associations between movement behaviors (physical activity (PA), sedentary time, sleep duration, screen time and sleep disturbance) and fat mass index (FMI), as well as to examine longitudinal associations between movement behaviors and FMI. METHODS: Cross-sectional and longitudinal analyses were done using data from the OPUS school meal study on 785 children (52% boys, 13.4% overweight, ages 8-11 years). Total PA, moderate-to-vigorous PA (MVPA), sedentary time and sleep duration (7 days and 8 nights) were assessed by an accelerometer and FMI was determined by dual-energy X-ray absorptiometry (DXA) on three occasions over 200 days. Demographic characteristics, screen time and sleep disturbance (Children's Sleep Habits Questionnaire) were also obtained. RESULTS: Total PA, MVPA and sleep duration were negatively associated with FMI, while sedentary time and sleep disturbances were positively associated with FMI (P⩽0.01). However, only total PA, MVPA and sleep duration were independently associated with FMI after adjustment for multiple covariates (P<0.001). Nevertheless, combined associations revealed synergistic effects among the different movement behaviors. Changes over time in MVPA were negatively associated with changes in FMI (P<0.001). However, none of the movement behaviors at baseline predicted changes in FMI (P>0.05), but higher FMI at baseline predicted a decrease in total PA and MVPA, and an increase in sedentary time (P⩽0.001), even in normal-weight children (P⩽0.03). CONCLUSION: Total PA, MVPA and sleep duration were independently associated with FMI, and combined associations of movement behaviors showed a synergistic effect with FMI. In the longitudinal study design, a high FMI at baseline was associated with lower PA and higher sedentary time after 200 days but not vice versa, even in normal-weight children. Our results suggest that adiposity is a better predictor of PA and sedentary behavior changes than the other way around.

Adaptive thermogenesis can make a difference in the ability of obese individuals to lose body weight.

The decrease in energy expenditure that occurs during weight loss is a process that attenuates over time the impact of a restrictive diet on energy balance up to a point beyond which no further weight loss seems to be possible. For some health professionals, such a diminished energy expenditure is the normal consequence of a progressive decrease in the motivation to exercise over the course of a weight-reducing program. Another explanation of decreased energy needs during weight loss is the decrease in body energy stores (that is, fat mass and muscle mass) and its related obligatory costs of living. Many studies have also documented the existence of adaptive thermogenesis in the context of weight loss, which represents a greater-than-predicted decrease in energy expenditure. In this paper, we pursue the analysis of this phenomenon by demonstrating that an adaptive decrease in thermogenesis can have a major role in the occurrence of resistance to further lose fat in weight-reduced obese individuals. Evidence is also presented to support the idea of greater hunger sensations in individuals displaying more pronounced thermogenic changes. Finally, as the decrease in thermogenesis persists over time, it is also likely associated with a greater predisposition to body-weight regain after weight loss. Globally, these observations suggest that the adaptive reduction in thermogenesis that accompanies a prolonged negative energy balance is a major determinant of the ability to spontaneously lose body fat.

[Food consumption in children and youth: effect of sedentary activities]. / Impact des activités sédentaires sur la prise alimentaire des jeunes.

Sedentary behavior has progressed with modern society, generating very low levels of energy expenditure and subsequent body weight disorders (obesity). There is also evidence that the absence of physical activity associated with short sleep time and watching television or playing video games leads to poor eating habits and favors high-energy intake. These findings have generally been reported in adults, with a few studies including data on children and adolescents. This brief review summarizes the current literature regarding the impact of such activities on food consumption and eating behavior in children and adolescents. There appears to be an uncoupling effect dissociating these activities from the sensation of hunger and thus energy intake. Children and adolescents seem to increase their energy intake during and after such activities without any alteration of their subjective appetite. In addition to considering the impact of sedentary behavior and physical activity level, future public health recommendations should also focus on associated nutritional adaptations (energy balance).

Longer sleep duration associates with lower adiposity gain in adult short sleepers.

The objective of this longitudinal, observational study was to verify whether a favorable change in sleep duration over 6 years could impact objective indicators of adiposity in adults aged 18-64 years. Short-duration sleepers (≤6 h per day; n=43) at baseline were divided into two groups: (i) those who increased their sleep duration to a 'healthy' length of 7-8 h per day at year 6 (mean increase: 1.52±0.66 h per day; n=23); and (ii) those who maintained their short sleep duration habits (mean change: -0.11±0.38 h per day; n=20). Adult individuals who reported sleeping 7-8 h per day at both baseline and year 6 (n=173) were used as a control group. Change in adiposity indicators for each sleep-duration group was compared by analysis of covariance. We observed that the two short-sleep-duration groups had similar baseline characteristics. However, short-duration sleepers who maintained their short sleep duration experienced a greater increase in body mass index (BMI) (difference: 1.1±0.36 kg m(-2), P<0.05) and fat mass (difference: 2.4±0.64 kg, P<0.05) over the 6-year follow-up period than short-duration sleepers who increased their sleep duration, even after adjustment for relevant covariates. We did not observe any significant difference in adiposity changes between the control group and short-duration sleepers who increased their sleep duration. This study suggests for the first time that shifting sleep duration from a short to a healthier length is associated with an attenuation of fat mass gain.

The glucostatic theory of appetite control and the risk of obesity and diabetes.

More than 50 years ago, Jean Mayer proposed that changes in blood glucose concentrations or arteriovenous glucose differences are detected by glucoreceptors that affect energy intake. According to this theory, an increase in blood glucose concentrations results in increased feelings of satiety whereas a drop in blood glucose concentrations has the opposite effect. The pioneering work of Mayer has recently received support from our group as low glycemia has been shown to be linked with body weight gain prospectively and has been considered as a strong predictor of the amount of weight regained after weight loss. This state of mild hypoglycemia also predicts the increase in depressive symptoms with weight loss and a greater propensity to glucose intolerance and type 2 diabetes, particularly for individuals having short sleep durations. Furthermore, knowledge-based work has been shown to induce a significant increase in spontaneous energy intake being related to changes in glycemic control. In accordance with the glucostatic theory, this oriented review suggests that factors favoring a trend toward hypoglycemia and/or glucose instability might induce excess energy intake, overweight and impaired glucose tolerance. Data also raise the possibility that fat gain might be protective against mild hypoglycemia by providing compensation to the stimuli promoted by a modern environment.

Integrating sedentary behavior in the theoretical model linking childhood to adulthood activity and health? An updated framework.

About 30 years ago, Blair and collaborators proposed a theoretical model illustrating the relationships between childhood and adulthood physical activity and health. The evolution of our societies has led to a "sedentarisation" of the subsequent generations, and the literature underlines an independent effect of physical activity and sedentary behaviors on health. We propose here an updated version of the model first designed by Blair and colleagues, suggesting the integration of the impact of sedentary behaviors on children and adult health.

Estimating sleep efficiency in 10- to- 13-year-olds using a waist-worn accelerometer.

OBJECTIVE: In field settings, wrist- and waist-worn accelerometers are typically used to assess sleep characteristics and movement behaviors, respectively. There has been a shift in movement behavior studies to wear accelerometers 24 h/d. Sleep characteristics could be assessed in these studies if sleep algorithms were available for waist-worn accelerometers. The objective of this study was to develop and provide validity data for an algorithm/sleep likelihood score cut-off to estimate sleep efficiency in children using the waist-worn Actical accelerometer. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty healthy children aged 10-13 years. MEASUREMENTS: Children wore an Actical on their waist and an Actiwatch 2 on their nondominant wrist for 8 nights at home in their normal sleep environment. Participants were randomized into algorithm/sleep likelihood score "development" and "test" groups (n=25 per group). Within the development group, we assessed sleep efficiency with the Actical using the same algorithm that the Actiwatch 2 uses and selected the sleep likelihood score cut-off value that was the most accurate at predicting sleep efficiency at the nightly level compared with the Actiwatch 2. We applied this algorithm and cut-off value to the test group. RESULTS: Mean (SD) sleep efficiency estimates for the test group from the Actical and Actiwatch 2 were 89.0% (3.9%) and 88.7% (3.1%), respectively. Bland-Altman plots and absolute difference scores revealed considerable agreement between devices for both nightly and weekly estimates of sleep efficiency. CONCLUSION: A waist-worn Actical accelerometer can accurately predict sleep efficiency in field settings among healthy 10- to 13-year-olds.