Using association rules mining to characterize loss of control eating in childhood.

Childhood loss of control (LOC)-eating, the perceived inability to stop or control eating, is associated with increased risk for binge-eating disorder and obesity. However, the correlates of LOC-eating in childhood remain unclear. A secondary analysis of 177, 7-12-year-old children from five laboratory feeding studies was performed to investigate potential family (e.g., frequency of meals together, feeding practices), parental (e.g., education, weight status), and child (e.g., weight status, appetite traits) correlates of LOC-eating. Association rules mining (ARM1), a data-driven approach, was used to examine all characteristics that were common across studies to identify which were associated with LOC-eating. Results showed LOC-eating was characterized by a combination of child appetitive behaviors and parental feeding practices. In particular, LOC-eating was associated with low parental pressure to eat in combination with a high propensity to want to eat all the time and frequent refusal or dislike of novel foods. This pattern of both food approach (i.e., wanting to eat all the time) and avoidant behaviors (i.e., food fussiness) highlights the need for more research to characterize the complex patterns of appetitive traits associated with LOC-eating. In contrast, the absence of LOC-eating was associated with a low propensity to want to eat all the time, greater family income, and infrequent emotional overeating. Therefore, propensity to want to eat all the time, a single question from the Children's Eating Behavior Questionnaire, characterized both the presence and absence of LOC-eating, highlighting the need for more research to determine if this question captures clinically relevant individual differences. Future studies addressing these questions will advance our understanding of pediatric LOC-eating and may lead to interventions to reduce risk for more severe eating disorder symptomology.

Initial Weight Change and Long-Term Changes in Weight and Compensation during Supervised Exercise Training.

INTRODUCTION: Our primary aim was to investigate the association between initial weight change and longer-term changes in weight and compensation (predicted weight loss-observed weight loss) during exercise. As secondary aims, we investigated if initial weight change was related to change in cardiometabolic risk markers and energy balance modulators. METHODS: Two 6-month randomized controlled exercise trials conducted in individuals with overweight or obesity were analyzed (study 1, n = 312; study 2, n = 102). In both studies, participants in an exercise condition (4 kcal·kg-1·wk-1 [KKW], 8 KKW, 12 KKW, or 20 KKW) were split into tertiles based on percent weight change from baseline to week 4. Tertiles 1 and 3 exhibited the least and most initial weight loss, respectively. Changes in end points were compared between tertiles. RESULTS: At month 6, weight loss was lower in tertile 1 than tertile 3 (study 1: -3.6%, 95% confidence interval [CI] = -4.6 to -2.6; study 2: -1.8%, 95% CI = -3.1 to -0.4; P ≤ 0.034). Tertile 1 also showed greater compensation than tertile 3 in study 1 (3.0 kg, 95% CI = 2.2 to 3.9) and study 2 (1.5 kg, 95% CI = 0.3 to 2.6; P ≤ 0.048). Changes in triglycerides and, in study 1, HDL cholesterol were less favorable in tertile 1 versus tertile 3 (P ≤ 0.043); however, changes in other cardiometabolic markers were similar (P ≥ 0.209). In study 2, tertile 1 increased energy intake and exhibited maladaptive changes in eating behaviors relative to tertile 3 (P < 0.050). No between-tertile differences in cumulative exercise energy expenditure and physical activity were evident (P ≥ 0.321). CONCLUSIONS: Less initial weight loss was associated with longer-term attenuated weight loss and greater compensation during aerobic exercise training. Individuals who display less initial weight loss during exercise may require early interventions to decrease compensation and facilitate weight loss.

Cold-Water Effects on Energy Balance in Healthy Women During Aqua-Cycling.

BACKGROUND: While the popularity of aquatic physical activities continues to grow among women, the effects on energy expenditure (EE) and appetite control remain unknown. The objective of this study was to examine the effect of water temperature during aqua-cycling session on EE, rate of perceived exertion, energy intake, appetite sensations, and food reward in healthy premenopausal women. METHODS: Participants completed three experimental sessions, in the postprandial condition, in a randomized order: a land control session (CON), an aqua-cycling session in 18 °C (EXO18), and an aqua-cycling session in 27 °C (EXO27). The EE, food intake, appetite sensations, and food reward were investigated for each condition. RESULTS: EXO18 induced a significant increase in EE (p < .001) and oxygen consumption (p < .01) compared with EXO27. The carbohydrate oxidation was higher in EXO18 session compared with EXO27 and CON (p < .05 and p < .001, respectively). While fat oxidation was higher in exercise sessions compared with CONT (p < .01), no difference was observed between EXO18 and EXO27. Exercise sessions did not alter absolute energy intake session but induced a decrease in relative energy intake (p < .001) and in hunger, desire to eat, and prospective food consumption compared with CON (p < .001). The authors also show here that cold-water exposure can increase EE while rate of perceived exertion is lower at the end of exercise session compared with same exercise at 27 °C (p < .05). CONCLUSION: An exposure to a moderately cold-water during aqua-cycling is an efficient strategy to promote increased EE and decreased hunger, which may be effective for energy balance management in healthy premenopausal women.

Factors Protecting against a Decline in Physical Activity during the COVID-19 Pandemic.

PURPOSE: The spread of COVID-19 and the associated stay-at-home orders and shutdowns of gyms and fitness centers have drastically influenced health behaviors leading to widespread reductions in physical activity (PA). The recent Call to Action from the American College of Sports Medicine has promoted "innovative strategies to promote PA during the COVID-19 pandemic." We aimed to identify individual-level factors that protected against declines in PA levels amid the COVID-19 restrictions. METHODS: We used the Pennington Biomedical COVID-19 Health Behaviors Survey for our analyses and used mixed-effect linear and generalized linear models to estimate the effects of individual-level factors on changes in PA levels during the COVID-19 restrictions. RESULTS: Participants (n = 4376) provided information on PA behaviors before and during the COVID-19 shutdown. Overall, PA levels declined by a mean ± SD of 112 ± 1460 MET·min·wk-1 during the COVID-19 shutdown; however, changes in PA were heterogeneous, with 55% of the participants reporting increases in or maintenance of PA during that time. Several social and demographic factors were significantly related to declines in PA, including high prepandemic PA levels, living alone (difference = 118 MET·min·wk-1), low household income (difference between the highest and the lowest income group = 363 MET·min·wk-1), COVID-19-related changes in income (difference = 110 MET·min·wk-1), and loss of employment (difference = 168 MET·min·wk-1). The substitution of prepandemic gym attendance with the purchase and use of home exercise equipment or exercise through virtual fitness platforms promoted increases in PA during the COVID-19 shutdown. CONCLUSIONS: While promoting PA through the COVID-19 pandemic, it is important to consider demographic factors, which greatly influence health behaviors and implementation of, and access to, replacement behaviors. The promotion of such strategies could help maintain PA levels during potential future stay-at-home orders.

The Impact of COVID-19 Stay-At-Home Orders on Health Behaviors in Adults.

OBJECTIVE: Stay-at-home orders in response to the coronavirus disease 2019 (COVID-19) pandemic have forced abrupt changes to daily routines. This study assessed lifestyle changes across different BMI classifications in response to the global pandemic. METHODS: The online survey targeting adults was distributed in April 2020 and collected information on dietary behaviors, physical activity, and mental health. All questions were presented as "before" and "since" the COVID-19 pandemic. RESULTS: In total, 7,753 participants were included; 32.2% of the sample were individuals with normal weight, 32.1% had overweight, and 34.0% had obesity. During the pandemic, overall scores for healthy eating increased (P < 0.001), owing to less eating out and increased cooking (P < 0.001). Sedentary leisure behaviors increased, while time spent in physical activity (absolute time and intensity adjusted) declined (P < 0.001). Anxiety scores increased 8.78 ± 0.21 during the pandemic, and the magnitude of increase was significantly greater in people with obesity (P ≤ 0.01). Weight gain was reported in 27.5% of the total sample compared with 33.4% in participants with obesity. CONCLUSIONS: The COVID-19 pandemic has produced significant health effects, well beyond the virus itself. Government mandates together with fear of contracting the virus have significantly impacted lifestyle behaviors alongside declines in mental health. These deleterious impacts have disproportionally affected individuals with obesity.

Validation of the Activity Preference Assessment: a tool for quantifying children's implicit preferences for sedentary and physical activities.

BACKGROUND: High levels of sedentary behavior and low physical activity are associated with poor health, and the cognitive determinants of these behaviors in children and adolescents are not well understood. To address this gap, we developed a novel, non-verbal, computer-based assessment to quantify the degree to which youth prefer to be sedentary relative to physically active in their leisure time. METHODS: The Activity Preference Assessment (APA) uses a forced-choice paradigm to understand implicit decision-making processes when presented with common sedentary and physical activities. The APA bias score ranges from - 100 to + 100, with positive scores indicating a relative preference for sedentary activities, and negative scores representing a preference for physical activities. In 60 children ages 8-17 years, we assessed the validity of this behavioral task against a free-choice play observation, accelerometry-measured activity, anthropometrics and body composition, and cardiorespiratory fitness. We explored neighborhood, family, and individual-level factors that may influence implicit activity preferences. Test-retest reliability was assessed over one week. RESULTS: The majority of children (67%) preferred sedentary relative to physical activities. APA bias scores were positively associated with sedentary time during free-choice play. In girls, bias scores were negatively associated with average daily MVPA. APA bias scores were positively associated with body fat and negatively associated with cardiorespiratory fitness. These findings were independent of age, sex, and race/ethnicity. Neighborhood access to physical activity spaces, the number of people in the home, perceived physical self-competence (e.g., coordination, strength), and self-reported depressive symptoms were associated with activity preferences. The intra-class correlation for test-retest reliability was r = 0.59. CONCLUSIONS: The APA shows promise as a novel tool for quantifying children's relative preference for sedentary versus physical activities. Implicit bias scores from the APA are clinically meaningful, as shown by significant associations with adiposity and cardiorespiratory fitness. Future longitudinal studies should examine the directionality of the association between preferences and health markers, and the degree to which implicit activity preferences are modifiable. Importantly, the task only takes an average of 10 min to complete, highlighting a potential role as an efficient screening tool for the propensity to be sedentary versus physically active. TRIAL REGISTRATION: ClinicalTrials.gov NCT03624582 .

Adaptations to exercise in compensators and noncompensators in the E-MECHANIC Trial.

Rating of perceived exertion (RPE) and respiratory exchange ratio (RER) have previously been associated with acute exercise compensation. This study examined adaptations in the RPE and RER with long-term exercise training in individuals who did (noncompensators) and did not (compensators) lose the expected amount of weight. Participants (n = 110, 71.8% women, means ± SD; age 49 ± 12 yr) completed 24 wk of supervised exercise training at 65-85% V̇o2peak to achieve a prescribed dose of 8 kcal·kg body wt-1·wk-1 (8 KKW) or 20 KKW. Participants were categorized as noncompensators (n = 55) or compensators (n = 55) based on the percent of expected weight loss (%EWL) achieved. Changes in RPE and RER during exercise over time (baseline, week 12, week 24) were compared by weight compensation category. Individual %EWL in relation to RPE, RER, and training intensity (%V̇o2peak) was evaluated over the same time period. RPE and RER for a given workload decreased from baseline to week 12 and stabilized through week 24, regardless of weight compensation (time P < 0.0001). Noncompensators had a higher RPE relative to heart rate, which was partly explained by higher %V̇o2peak. RPE and %V̇o2peak both positively predicted %EWL, independent of age, sex, and exercise dose. Training intensity and RPE were positively associated with weight loss on the individual level, warranting further investigation into self-selection in exercise-based programs. Understanding individual heterogeneity in training intensity and behavioral responses may improve future weight management efforts that involve exercise.NEW & NOTEWORTHY In sedentary individuals with overweight and obesity, achievement of expected weight loss from long-term exercise training was associated with individual adaptations in perceived exertion. Contrary to our hypothesis, those with higher relative perceived exertion achieved a larger proportion of their expected weight loss, which was partly explained by a higher self-selected exercise training intensity.

Effects of COVID-19 Lockdown on Lifestyle Behaviors in Children with Obesity Living in Verona, Italy: A Longitudinal Study.

OBJECTIVE: The aim of this study was to test the hypothesis that youths with obesity, when removed from structured school activities and confined to their homes during the coronavirus disease 2019 pandemic, will display unfavorable trends in lifestyle behaviors. METHODS: The sample included 41 children and adolescents with obesity participating in a longitudinal observational study located in Verona, Italy. Lifestyle information including diet, activity, and sleep behaviors was collected at baseline and 3 weeks into the national lockdown during which home confinement was mandatory. Changes in outcomes over the two study time points were evaluated for significance using paired t tests. RESULTS: There were no changes in reported vegetable intake; fruit intake increased (P = 0.055) during the lockdown. By contrast, potato chip, red meat, and sugary drink intakes increased significantly during the lockdown (P value range, 0.005 to < 0.001). Time spent in sports activities decreased by 2.30 (SD 4.60) h/wk (P = 0.003), and sleep time increased by 0.65 (SD 1.29) h/d (P = 0.003). Screen time increased by 4.85 (SD 2.40) h/d (P < 0.001). CONCLUSIONS: Recognizing these adverse collateral effects of the coronavirus disease 2019 pandemic lockdown is critical in avoiding depreciation of weight control efforts among youths afflicted with excess adiposity. Depending on duration, these untoward lockdown effects may have a lasting impact on a child's or adolescent's adult adiposity level.

A Pilot Study of Cardiorespiratory Fitness, Adiposity, and Cardiometabolic Health in Youth With Overweight and Obesity.

OBJECTIVE: To conduct a preliminary assessment of the relationships between cardiorespiratory fitness, adiposity, and cardiometabolic health using gold standard measures in diverse youth ranging from overweight to severe obesity. METHODS: Twenty of 30 participants (mean [SD]; age 13.2 [1.8] y, 55% female, 45% African American) met the criteria for VO2peak during a graded cycle ergometer test to volitional fatigue. The body composition was measured by dual-energy X-ray absorptiometry (percentage of body fat, fat mass index, and fat-free mass) and magnetic resonance imaging (abdominal visceral and subcutaneous [SAT] adipose tissue). The VO2peak was expressed relative to fat-free mass. Fasting lipid levels, glycemic biomarkers, and vital signs were examined individually and used in a composite cardiometabolic risk score. Accelerometer-measured physical activity and sedentary time were included as covariates. RESULTS: VO2peak was negatively associated with abdominal SAT (r = -.49, P < .05), but not visceral adipose tissue or markers of cardiometabolic health. The association between SAT and VO2peak was partly explained by habitual sedentary time. CONCLUSIONS: We demonstrated a significant negative association between cardiorespiratory fitness and SAT in a diverse group of high-risk youth. The inclusion of rigorous, laboratory-based measures and youth with severe obesity extends the previous work in pediatric populations.

Change in self-efficacy, eating behaviors and food cravings during two years of calorie restriction in humans without obesity.

Calorie restriction (CR) enhances longevity in humans who are normal weight, overweight and obese. While dietary regimens can change self-efficacy, eating behaviors, and food cravings in individuals with obesity, the responses of these measures to prolonged CR in individuals who are exclusively not obese is unknown. The aim of this analysis was to test the effects of a two-year CR intervention on self-efficacy and eating attitudes and behaviors in humans without obesity by analyzing data from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE 2) study. Participants (n = 218, BMI range = 21.3-29.0 kg/m2) were randomized to a 25% CR group or an ad libitum (AL) group. Eating attitudes and behaviors and self-efficacy were assessed using validated questionnaires at baseline, month 12, and month 24. Dietary restraint and self-efficacy increased in the CR compared to the AL group (ES ≥ 0.32). Increased self-efficacy was negatively related to weight change (ρ < -0.24). In the CR group, males showed a reduction in cravings for carbohydrates and fats at month 24, whereas females did not. The CR group showed elevations in state hunger, which were transient, and disinhibited eating (ES ≥ 0.37). In individuals without obesity, dietary restraint and self-efficacy could be important in promoting long-term CR for individuals looking to use CR as a tool to improve longevity.

Perceptual Characterization of the Macronutrient Picture System (MaPS) for Food Image fMRI.

Food image fMRI paradigms are used widely for investigating the neural basis of ingestive behavior. However, these paradigms have not been validated in terms of ingestive behavior constructs, engagement of food-relevant neural systems, or test-retest reliability, making the generalizability of study findings unclear. Therefore, we validated the Macronutrient Picture System (MaPS) (McClernon et al., 2013), which includes food images from the six categories represented in the Geiselman Food Preference Questionnaire (FPQ) (Geiselman et al., 1998). Twenty-five healthy young adults (n = 21 female, mean age = 20.6 ± 1.1 years, mean BMI = 22.1 ± 1.9 kg/m2) rated the MaPS images in terms of visual interest, appetitive quality, nutrition, emotional valence, liking, and frequency of consumption, and completed the FPQ. In a second study, 12 individuals (n=8 female, mean age = 25.0 ± 6.5 years, mean BMI = 28.2 ± 8.7 kg/m2) viewed MaPS and control images (vegetables and non-food) during two separate 3T BOLD fMRI scans after fasting overnight. Intuitively, high fat/high sugar (HF/HS) and high fat/high complex carbohydrate (HF/HCCHO) images achieved higher liking and appetitive ratings, and lower nutrition ratings, than low fat/low complex carbohydrate/high protein (LF/LCHO/HP) images on average. Within each food category, FPQ scores correlated strongly with MaPS image liking ratings (p < 0.001). Brain activation differences between viewing images of HF/HS and vegetables, and between HF/HCCHO and vegetables, were seen in several reward-related brain regions (e.g., putamen, insula, and medial frontal gyrus). Intra-individual, inter-scan agreement in a summary measure of brain activation differences in seven reward network regions of interest was high (ICC = 0.61), and was even higher when two distinct sets of food images with matching visual ratings were shown in the two scans (ICC = 0.74). These results suggest that the MaPS provides valid representation of food categories and reliably activates food-reward-relevant neural systems.

Brain response to food cues varying in portion size is associated with individual differences in the portion size effect in children.

Large portions promote intake of energy dense foods (i.e., the portion size effect--PSE), but the neurobiological drivers of this effect are not known. We tested the association between blood oxygen level dependent (BOLD) brain response to food images varied by portion size (PS) and energy density (ED) and children's intake at test-meals of high- and low-ED foods served at varying portions. Children (N = 47; age 7-10 years) participated in a within-subjects, crossover study consisting of 4 meals of increasing PS of high- and low-ED foods and 1 fMRI to evaluate food images at 2 levels of PS (Large, Small) and 2 levels of ED (High, Low). Contrast values between PS conditions (e.g., Large PS - Small PS) were calculated from BOLD signal in brain regions implicated in cognitive control and reward and input as covariates in mixed models to determine if they moderated the PSE curve. Results showed a significant effect of PS on intake. Responses to Large relative to Small PS in brain regions implicated in salience (e.g., ventromedial prefrontal cortex and orbitofrontal cortex) were positively associated with the linear slope (i.e., increase in intake from baseline) of the PSE curve, but negatively associated with the quadratic coefficient for the total meal. Responses to Large PS High ED relative to Small PS High ED cues in regions associated with cognitive control (e.g., dorsolateral prefrontal cortex) were negatively associated with the linear slope of the PSE curve for high-ED foods. Brain responses to PS cues were associated with individual differences in children's susceptibility to overeating from large portions. Responses in food salience regions positively associated with PSE susceptibility while activation in control regions negatively associated with PSE susceptibility.

Brain reactivity to visual food stimuli after moderate-intensity exercise in children.

Exercise may play a role in moderating eating behaviors. The purpose of this study was to examine the effect of an acute bout of exercise on neural responses to visual food stimuli in children ages 8-11 years. We hypothesized that acute exercise would result in reduced activity in reward areas of the brain. Using a randomized cross-over design, 26 healthy weight children completed two separate laboratory conditions (exercise; sedentary). During the exercise condition, each participant completed a 30-min bout of exercise at moderate-intensity (~ 67% HR maximum) on a motor-driven treadmill. During the sedentary session, participants sat continuously for 30 min. Neural responses to high- and low-calorie pictures of food were determined immediately following each condition using functional magnetic resonance imaging. There was a significant exercise condition*stimulus-type (high- vs. low-calorie pictures) interaction in the left hippocampus and right medial temporal lobe (p < 0.05). Main effects of exercise condition were observed in the left posterior central gyrus (reduced activation after exercise) (p < 0.05) and the right anterior insula (greater activation after exercise) (p < 0.05). The left hippocampus, right medial temporal lobe, left posterior central gyrus, and right anterior insula appear to be activated by visual food stimuli differently following an acute bout of exercise compared to a non-exercise sedentary session in 8-11 year-old children. Specifically, an acute bout of exercise results in greater activation to high-calorie and reduced activation to low-calorie pictures of food in both the left hippocampus and right medial temporal lobe. This study shows that response to external food cues can be altered by exercise and understanding this mechanism will inform the development of future interventions aimed at altering energy intake in children.

Perceived Exertion during Exercise Is Associated with Children's Energy Intake.

PURPOSE: To examine the individual-level factors that predict energy intake (EI) after imposed exercise (EX) and sedentary time (SED) in children. METHODS: Healthy-weight children ages 9-12 yr (n = 20) reported to the laboratory for one baseline and two experimental visits (EX and SED) each separated by 1 wk in a randomized crossover design. Percent body fat, weight (kg), and height (m) were used to calculate fat-mass index (FM index) and fat-free mass index (FFM index; kg·m). On the EX day, children exercised at 70% estimated V˙O2peak for 30 min on a cycle ergometer, whereas cardiovascular responses and RPE were measured. Objective EI (kcal) was measured at identical meals (breakfast, lunch, snack, and dinner) on the EX and SED days. RESULTS: Total EI was not statistically different between the EX and SED days (t = 1.8, P = 0.09). FFM index was positively associated with EI on the EX day (r = 0.54, P < 0.05). RPE was also positively associated with EI on the EX day (r = 0.82, P < 0.001). Together, FFM index and RPE explained 77% of the variability in EX day EI (F(2,17) = 26.4, P < 0.001). For each unit increase in RPE, children consumed approximately 270 more calories on the EX day. A similar pattern of associations was observed on the SED day. CONCLUSIONS: FFM index was positively associated with EI on the EX day. Despite experiencing the same 70% relative exercise intensity, increased perceived difficulty predicted greater EI on both the EX and SED day. These findings demonstrate a role for both FFM and RPE in explaining EI variability in children.

Food portion size and energy density evoke different patterns of brain activation in children.

BACKGROUND: Large portions of food promote intake, but the mechanisms that drive this effect are unclear. Previous neuroimaging studies have identified the brain-reward and decision-making systems that are involved in the response to the energy density (ED) (kilocalories per gram) of foods, but few studies have examined the brain response to the food portion size (PS). OBJECTIVE: We used functional MRI (fMRI) to determine the brain response to food images that differed in PSs (large and small) and ED (high and low). DESIGN: Block-design fMRI was used to assess the blood oxygen level-dependent (BOLD) response to images in 36 children (7-10 y old; girls: 50%), which was tested after a 2-h fast. Pre-fMRI fullness and liking were rated on visual analog scales. A whole-brain cluster-corrected analysis was used to compare BOLD activation for main effects of the PS, ED, and their interaction. Secondary analyses were used to associate BOLD contrast values with appetitive traits and laboratory intake from meals for which the portions of all foods were increased. RESULTS: Compared with small-PS cues, large-PS cues were associated with decreased activation in the inferior frontal gyrus (P < 0.01). Compared with low-ED cues, high-ED cues were associated with increased activation in multiple regions (e.g., in the caudate, cingulate, and precentral gyrus) and decreased activation in the insula and superior temporal gyrus (P < 0.01 for all). A PS × ED interaction was shown in the superior temporal gyrus (P < 0.01). BOLD contrast values for high-ED cues compared with low-ED cues in the insula, declive, and precentral gyrus were negatively related to appetitive traits (P < 0.05). There were no associations between the brain response to the PS and either appetitive traits or intake. CONCLUSIONS: Cues regarding food PS may be processed in the lateral prefrontal cortex, which is a region that is implicated in cognitive control, whereas ED activates multiple areas involved in sensory and reward processing. Possible implications include the development of interventions that target decision-making and reward systems differently to moderate overeating.

Impact of imposed exercise on energy intake in children at risk for overweight.

BACKGROUND: Exercise not only has a direct effect on energy balance through energy expenditure (EE), but also has an indirect effect through its impact on energy intake (EI). This study examined the effects of acute exercise on daily ad libitum EI in children at risk for becoming overweight due to family history. METHODS: Twenty healthy-weight children (ages 9-12 years, 12 male/8 female) with at least one overweight biological parent (body mass index ≥ 25 kg/m2) participated. Children reported to the laboratory for one baseline and two experimental visits (EX = exercise, SED = sedentary) each separated by 1 week in a randomized crossover design. Two hours into the EX day session, children exercised at 70 % estimated VO2max for 30 min on a cycle ergometer. Objective EI (kcal) was measured at a standard breakfast (~285 kcal) and ad libitum lunch, snack and dinner. Meals were identical on the EX and SED days. Activity-related EE (kcal) was estimated with accelerometers worn on the non-dominant wrist and ankle. Relative EI (kcal) was computed as the difference between Total EI and Activity-related EE for each testing day. Paired t-tests were performed to test differences in Total EI, Activity-related EE and Relative EI between the EX and SED days. RESULTS: Across all meals, Total EI was not statistically different between the EX and SED days (t = 1.8, p = 0.09). Activity-related EE was greater on the EX day compared to the SED day (t = 10.1, p < 0.001). By design, this difference was predominantly driven by activity during the morning (t = 20.4, p < 0.001). Because children consumed a similar number of kcal on each day, but had greater Activity-related EE on the EX day, Relative EI was lower (t = -5.15, p < 0.001) for the EX day (1636 ± 456 kcal) relative to the SED day (1862 ± 426 kcal). CONCLUSIONS: Imposed exercise was effective in reducing Relative EI compared to being sedentary. Morning exercise may help children at risk for becoming overweight to better regulate their energy balance within the course of a day.

Brain response to images of food varying in energy density is associated with body composition in 7- to 10-year-old children: Results of an exploratory study.

Energy balance is regulated by a multifaceted system of physiological signals that influence energy intake and expenditure. Therefore, variability in the brain's response to food may be partially explained by differences in levels of metabolically active tissues throughout the body, including fat-free mass (FFM) and fat mass (FM). The purpose of this study was to test the hypothesis that children's body composition would be related to their brain response to food images varying in energy density (ED), a measure of energy content per weight of food. Functional magnetic resonance imaging (fMRI) was used to measure brain response to High (>1.5kcal/g) and Low (<1.5kcal/g) ED food images, and Control images, in 36 children ages 7-10years. Body composition was measured using bioelectrical impedance analysis. Multi-subject random effects general linear model (GLM) and two-factor repeated measures analysis of variance (ANOVA) were used to test for main effects of ED (High ED vs. Low ED) in a priori defined brain regions of interest previously implicated in energy homeostasis and reward processing. Pearson's correlations were then calculated between activation in these regions for various contrasts (High ED-Low ED, High ED-Control, Low ED-Control) and child body composition (FFM index, FM index, % body fat). Relative to Low ED foods, High ED foods elicited greater BOLD activation in the left thalamus. In the right substantia nigra, BOLD activation for the contrast of High ED-Low ED foods was positively associated with child FFM. There were no significant results for the High ED-Control or Low ED-Control contrasts. Our findings support literature on FFM as an appetitive driver, such that greater amounts of lean mass were associated with greater activation for High ED foods in an area of the brain associated with dopamine signaling and reward (substantia nigra). These results confirm our hypothesis that brain response to foods varying in energy content is related to measures of child body composition.

Intake at a single, palatable buffet test meal is associated with total body fat and regional fat distribution in children.

Previous studies testing the relationship between short-term, ad libitum test-meal intake and body composition in children have shown inconsistent relationships. The objective of this study was to determine whether children's intake at a palatable, buffet meal was associated with body composition, assessed by dual-energy X-ray absorptiometry (DXA). A sample of 71 children (4-6 years) participated in 4 sessions where ad libitum food intake was measured. Children's intake at two of the test-meals was retained for the present analysis: a baseline meal consisting of moderately palatable foods and a highly palatable buffet including sweets, sweet-fats, and savory-fats. On the last visit, anthropometrics and DXA were assessed to determine child body composition. Children consumed significantly more calories at the palatable buffet compared to the baseline test-meal. Children's total fat-free mass was positively associated with intake at both the baseline meal and the palatable buffet meal. Total energy intake at both meals and intake of savory-fats at the palatable buffet were positively associated with children's total fat mass, total percent body fat, and percent android fat. Intake of sweet-fats was associated with child fat-free mass index. Intake of sweets was not correlated with body composition. Children's intake at a palatable test-meal, particularly of savory-fat foods, was associated with measures of total and regional body fat.