Comparison of total energy expenditure between school and summer months

Rethinking children's right to leisure during school holidays

Leisure and health are human rights that apply to both children and adults. Leisure can enhance health and enable people to participate fully in leisure activities. One of children's main opportunities for leisure is during school holidays. Little previous research has focused on this time in children's lives. This paper presents a review of the literature surrounding school holidays, providing a critique of educational and public health approaches that focus narrowly on children's future outcomes that may be associated with how they spend their time during these leisure periods. It argues that a more sociological understanding, rooted within child-centred approaches to leisure, provides the opportunity for children's agency, participation and citizenship to be investigated more fully.

Total energy expenditure measured by doubly labeled water method in children and adolescents: a systematic review

Total energy expenditure (TEE) is essential for understanding the growth, development, and physical activity of children and adolescents. This study aimed to summarize the existing evidence on TEE measured using the doubly labeled water (DLW) technique in children and adolescents aged 1-18 years. Furthermore, this review compared TEE between obese and normal-weight participants. This systematic review used the PubMed, ScienceDirect, Web of Science, and EBSCO databases. These studies were limited to those published in English between January 2000 and December 2021. Articles presenting objectively measured data on the TEE of children and adolescents aged 1-18 years measured using the DLW method were included. Physical activity level (PAL; TEE/basal metabolic rate [BMR]) and BMR data were also obtained. The search strategy identified 2,351 articles, of which 63 (n=4,283 children and adolescents; 45.4% male) met the selection criteria. The participants in the 10 studies were overweight or obese (n=413). In our study, TEE increased in male and female participants aged 1-18 years. PAL increased with age in males (y=0.0272x+1.3887, r2=0.511) and females (y=0.0199x+1.401, r2=0.335), and the slope of PAL with age did not differ between males and females. The TEE of obese and overweight participants was higher than that of normal-weight participants, but the slope of TEE did not differ between normal-weight (y=132.99x+702.24, r2=0.877) and obese individuals (y=136.18x+1,037.9, r2=0.842). In conclusion, this review provides convincing evidence that daily TEE progressively increases with growth in males and females aged 1-18 years.

Obesity: an evolutionary context

People completely lacking body fat (lipodystrophy/lipoatrophy) and those with severe obesity both show profound metabolic and other health issues. Regulating levels of body fat somewhere between these limits would, therefore, appear to be adaptive. Two different models might be contemplated. More traditional is a set point (SP) where the levels are regulated around a fixed level. Alternatively, dual-intervention point (DIP) is a system that tolerates fairly wide variation but is activated when critically high or low levels are breached. The DIP system seems to fit our experience much better than an SP, and models suggest that it is more likely to have evolved. A DIP system may have evolved because of two contrasting selection pressures. At the lower end, we may have been selected to avoid low levels of fat as a buffer against starvation, to avoid disease-induced anorexia, and to support reproduction. At the upper end, we may have been selected to avoid excess storage because of the elevated risks of predation. This upper limit of control seems to have malfunctioned because some of us deposit large fat stores, with important negative health effects. Why has evolution not protected us against this problem? One possibility is that the protective system slowly fell apart due to random mutations after we dramatically reduced the risk of being predated during our evolutionary history. By chance, it fell apart more in some people than others, and these people are now unable to effectively manage their weight in the face of the modern food glut. To understand the evolutionary context of obesity, it is important to separate the adaptive reason for storing some fat (i.e. the lower intervention point), from the nonadaptive reason for storing lots of fat (a broken upper intervention point). The DIP model has several consequences, showing how we understand the obesity problem and what happens when we attempt to treat it.

Impact of COVID-19 Lockdown on Body Weight, Eating Habits, and Physical Activity of Jordanian Children and Adolescents

OBJECTIVE

The lockdown for the COVID-19 pandemic affects lifestyle patterns globally and impacts children and adolescents. This study aims to assess the effect of the lockdown on body weight, eating habits, and physical activity of Jordanian youth (children and adolescents).

METHODS

A cross-sectional study was conducted on a sample of 477 Jordanian children and adolescents aged 6-17 y. The study tool was a structured validated questionnaire. It comprised 4 parts, including a general description of the study purpose, sociodemographic and anthropometric data, physical activity data, and food intake pattern. Questions were reported before and during lockdown. Changes in outcomes over the 2 study time points were evaluated.

RESULTS

After the lockdown period, the mean body weight and body mass index for age Z-scores (BAZ) showed a significant increase (P < 0.001) compared with before the lockdown period. More than 50% of the subjects reported that they spent more than 3 h in front of the screen during the lockdown. The percent of subjects who watched TV for more than 3h was increased. Moreover, physical inactivity was increased significantly during the lockdown. All food groups consumption was significantly increased during the lockdown compared to before the lockdown.

CONCLUSIONS

COVID-19 lockdown period was characterized by an increase in the use of screen-based devices, lower physical activity, uncontrolled food intake, and weight gain.

A qualitative exploration of potential determinants of accelerated summer weight gain among school-age children: perspectives from parents

Background

There is growing evidence that school children in the United States gain weight more rapidly during the summer than the school year, but few studies have explored the causes of this phenomenon. The goal of this study was to qualitatively explore potential determinants of accelerated summer weight gain by interviewing parents of school-age children.

Methods

Key informant interviews were conducted with parents of third and fourth grade students enrolled in a school-based physical activity intervention in three peri-urban communities in Eastern Massachusetts. A structured interview guide was developed to assess school year and summertime differences in child diet, physical activity, daily routine, and family rules. Interviews were recorded and transcribed verbatim. Transcripts were coded and major themes were identified using thematic analysis.

Results

Summer activities varied substantially by family. Many parents characterized summer as a time with less structure and more relaxed rules, particularly around bedtime and screen use. Parents perceived their child to be more physically active in the summer and reported few barriers to summertime physical activity. Parents reported increases in both positive (increased consumption of fruits and vegetables) and negative (increased consumption of “sweets” and “junk foods”) dietary behaviors. They highlighted several stressors unique to summer, such as the high cost of camps and the need to coordinate childcare and manage children’s time.

Conclusions

Parents perceived their children to be more physically active in the summer and consume more fruits and vegetables than during the school year. However, they also perceived children to consume more energy-dense, nutrient poor foods, engage in more screen time, and have later bedtimes during the summer. These behaviors are important targets for summertime obesity prevention interventions. Large-scale quantitative studies are needed to determine whether these parent perceptions reflect meaningful risk factors for accelerated summer weight gain.

Life on holidays: study protocol for a 3-year longitudinal study tracking changes in children's fitness and fatness during the in-school versus summer holiday period

BACKGROUND

Emerging evidence suggests that children become fatter and less fit over the summer holidays but get leaner and fitter during the in-school period. This could be due to differences in diet and time use between these distinct periods. Few studies have tracked diet and time use across the summer holidays. This study will measure rates of change in fatness and fitness of children, initially in Grade 4 (age 9 years) across three successive years and relate these changes to changes in diet and time use between in-school and summer holiday periods.

METHODS

Grade 4 Children attending Australian Government, Catholic and Independent schools in the Adelaide metropolitan area will be invited to participate, with the aim of recruiting 300 students in total. Diet will be reported by parents using the Automated Self-Administered 24-h Dietary Assessment Tool. Time use will be measured using 24-h wrist-worn accelerometry (GENEActiv) and self-reported by children using the Multimedia Activity Recall for Children and Adults (e.g. chores, reading, sport). Measurement of diet and time use will occur at the beginning (Term 1) and end (Term 4) of each school year and during the summer holiday period. Fitness (20-m shuttle run and standing broad jump) and fatness (body mass index z-score, waist circumference, %body fat) will be measured at the beginning and end of each school year. Differences in rates of change in fitness and fatness during in-school and summer holiday periods will be calculated using model parameter estimate contrasts from linear mixed effects model. Model parameter estimate contrasts will be used to calculate differences in rates of change in outcomes by socioeconomic position (SEP), sex and weight status. Differences in rates of change of outcomes will be regressed against differences between in-school and summer holiday period diet and time use, using compositional data analysis. Analyses will adjust for age, sex, SEP, parenting style, weight status, and pubertal status, where appropriate.

DISCUSSION

Findings from this project may inform new, potent avenues for intervention efforts aimed at addressing childhood fitness and fatness. Interventions focused on the home environment, or alternatively extension of the school environment may be warranted.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry, identifier ACTRN12618002008202 . Retrospectively registered on 14 December 2018.

Life on holidays: differences in activity composition between school and holiday periods in Australian children

BACKGROUND

Recently, a small number of studies have suggested that gains in fitness and reductions in body fat achieved during the school term are reversed or stagnate during the holiday period. This may be associated with changed activity patterns. The aim of this study was to compare 24-h activity compositions between school and holiday periods in Australian children.

METHODS

The participants in this study were 366 children (53% female, 13.4 ± 2.3 years) who were a subgroup of the 2007 Australian National Children's Nutrition and Physical Activity Survey. Each child recalled use of time on at least one school day, one weekend day and one holiday using the Multimedia Activity Recall for Children and Adults. Composite "in-term" and "holiday" use-of-time profiles were generated by weighting school days by 5, and weekends by 2 where data were available. Difference between holiday and in-term time use was assessed using a compositional multivariate linear model for repeated measures. Subsequent models tested for interaction between time of measurement and socio-economic status or body mass index.

RESULTS

Time use was significantly different between holidays and in-term days (F = 103, p < 0.0001). On holidays, children accumulated 140 min less School-related time, compensated by sleeping 40 min longer, 58 min more Screen Time, and 35 min more Domestic/Social time. Children spent 10 min less in vigorous physical activity, and although sitting time was 33 min/day less during holidays, estimated total daily energy expenditure (TDEE) was 5.4% lower. Differences between holiday and in-term activity compositions did not vary by parental education (F = 1.2, p = 0.25), postcode-level socio-economic status (F = 0.9, p = 0.56) or weight status (F = 1.7, p = 0.07).

CONCLUSIONS

In this subsample of a nationally representative survey of Australian children, holidays were characterised by longer sleep and higher TV and videogame time, lower vigorous activity and lower TDEE. Uncompensated by dietary adjustments, these differences would result in an accumulation of about 650 g of fat over a six-week holiday period. Holiday activity patterns may be a promising focus for obesity prevention efforts.

The Association of the Body Composition of Children with 24-Hour Activity Composition

OBJECTIVES

To evaluate how the reallocation of time between sleep, sedentary time, light, and moderate-vigorous activities is associated with children's body composition.

STUDY DESIGN

Population-based cross-sectional Child Health CheckPoint within the Longitudinal Study of Australian Children (n = 938 11-12 year-olds, 50% boys). Twenty-four hour activity composition via accelerometry (minutes/day of sleep, sedentary time, light, and moderate-to-vigorous physical activity [MVPA]) and 3-part body composition (percentage truncal fat, percentage nontruncal fat, and percentage fat-free mass) via bioelectrical impedance analysis were measured. We estimated differences in 3-part body composition associated with the incremental reallocation of time between activities, using dual-compositional regression models adjusted for sex, age, puberty, and socioeconomic position.

RESULTS

Reallocation of time between MVPA and any other activity was strongly associated with differences in body composition. Adverse body composition differences were larger for a given MVPA decrease than were the beneficial differences for an equivalent MVPA increase. For example, 15 minutes less MVPA (relative to remaining activities) was associated with absolute percentage differences of +1.7% (95% CI 1.2; 2.4) for truncal fat, +0.8% (0.6; 1.2) for nontruncal fat, and -2.6% (-3.5; -1.9) for fat-free mass, and a 15-minute increase was associated with -0.7% (-0.9; -0.5) truncal fat, -0.4% (-0.5; -0.3) nontruncal fat, and +1.1% (0.9; 1.5) fat-free mass. Reallocations between sleep, sedentary time, and light physical activity were not associated with differences in body composition.

CONCLUSIONS

Preventing declines in MVPA during inactive periods (eg, holidays) may be an important intervention goal. More MVPA, instead of other activities, may benefit body composition.

Seasonal variation in body mass, body composition and activity-induced energy expenditure: a long-term study

BACKGROUND/OBJECTIVES

Seasonal variation in body mass is a model for the study of body mass regulation. Here a long-term study is presented on body mass, body composition, and activity-induced energy expenditure in a subject with a large seasonal variation in body mass of about 3.0 kg.

SUBJECT/METHODS

Body mass was assessed daily over >20 consecutive years. Daily assessment of activity-induced energy expenditure was performed over the last 10 years. Body composition was assessed monthly for 1 year in the middle and at the end of the observation interval. Additionally, data were compared with data on body composition, resting energy expenditure, and total daily energy expenditure of the same subject as a participant in published studies.

RESULTS

Body mass showed a pronounced seasonal variation, associated with a synchronous variation in physical activity. Body mass peaked in the cold winter months when physical activity reached the lowest annual value and decreased to the lowest value in mid-summer when daily physical activity peaked. The seasonal variation in body mass consisted mainly of body fat. Longitudinally, over the past 8 years of the observation interval, average fat-free mass showed a decrease of 1.0 kg and fat mass increased 0.8 kg.

CONCLUSIONS

In a subject with a pronounced seasonal variation in physical activity, activity-induced variation in energy requirement was covered by an annual variation in body mass, mainly as fat. Maintenance of activity-induced energy expenditure did not protect against loss of fat-free body mass with advancing age.

Changes in Weight, Sedentary Behaviour and Physical Activity during the School Year and Summer Vacation

Background: To examine bidirectional associations between body weight and objectively assessed sedentary behaviour (SB) and physical activity (PA) during the school year and summer vacation. Methods: Participants were 209 Japanese boys and girls (9.0 ± 1.8 years at baseline). SB and PA were measured using triaxial accelerometry that discriminated between ambulatory and non-ambulatory PA, screen time measured by questionnaire during the school-term was evaluated in May and the summer vacation, and relative body weight measured in May and just after the end of summer vacation. Results: There were no significant relationships between changes in SB or PA and changes in body weight. However, higher relative body weight at baseline was associated with decreased non-ambulatory moderate PA (p = 0.049), but this association was slightly diminished after adjusting for change in SB (p = 0.056). Longer screen time at baseline was also associated with increased relative body weight (p = 0.033). Conclusions: The present study revealed that body weight might be particularly influential on non-ambulatory moderate PA while SB, PA or changes in these variables did not predict changes in body weight. Moreover, screen time during the school year is a predictor of change in relative body weight during the subsequent summer vacation.

Impact of child summertime obesity interventions on body mass index, and weight-related behaviours: a systematic review and meta-analysis protocol

INTRODUCTION

In previous studies, it has been found that on average, children consistently gained weight during the summer months at an increased rate compared with the 9-month school year. This contributed to an increased prevalence of overweight and obesity in children. Several obesity-related interventions have occurred during or targeting the summer months. We propose to conduct a systematic review and meta-analysis of the impact of obesity prevention and treatment interventions for school-age children conducted during the summer or targeting the summer months when children are not in school on their body mass index (BMI), or weight-related behaviours.

METHODS AND ANALYSES

A literature search will be conducted by the first author (JPM) using MEDLINE/PubMed, Cochrane Library, Scopus, CINAHL, PsycINFO, EMBASE and Proquest Dissertations and Theses databases from the date of inception to present. Studies must examine interventions that address the modification or promotion of weight-related behaviours (eg, dietary patterns, eating behaviours, physical activity (PA), sedentary behaviour or sleep) and target school-age children (ages 5-18). The primary outcomes will be changes from baseline to postintervention and/or the last available follow-up measurement in weight, BMI, BMI percentile, standardised BMI or per cent body fat. Secondary outcomes will include changes in dietary intake, PA, sedentary behaviour or sleep. Risk of bias will be assessed using the Cochrane risk of bias tool for randomised and non-randomised studies, as appropriate.

ETHICS AND DISSEMINATION

Because this is a protocol for a systematic review, ethics approval will not be required. The findings will be disseminated via presentations at scientific conferences and published in a peer-reviewed journal. All amendments to the protocol will be documented and dated and reported in the PROSPERO trial registry.

PROSPERO REGISTRATION NUMBER

CRD42016041750.

Effect of the Holiday Season on Weight Gain: A Narrative Review

Several studies suggest that the holiday season, starting from the last week of November to the first or second week of January, could be critical to gaining weight. This study aims to review the literature to determine the effects of the holidays on body weight. In studies of adults, a significant weight gain was consistently observed during this period (0.4 to 0.9 kg, p < 0.05). The only study in college students found an effect on body fat but not on weight (0.1 kg, p = 0.71). The only study found in children did not show an effect on BMI percentile (-0.4%, p > 0.05) during this period. Among individuals with obesity who attempt to lose weight, an increase in weight was observed (0.3 to 0.9 kg, significant in some but not in all studies), as well as increase in weight in motivated self-monitoring people (0.4 to 0.6%, p < 0.001). Programs focused on self-monitoring during the holidays (phone calls and daily mailing) appeared to prevent weight gain, but information is limited. The holiday season seems to increase body weight in adults, even in participants seeking to lose weight and in motivated self-monitoring people, whereas in children, adolescents, and college students, very few studies were found to make accurate conclusions.

Improving Urban Minority Girls' Health Via Community Summer Programming

Summertime has emerged as a high-risk period for weight gain among low-income minority youth who often experience a lack of resources when not attending school. Structured programming may be an effective means of reducing risk for obesity by improving obesogenic behaviors among these youth. The current multi-method study examined sedentary time, physical activity, and dietary intake among low-income urban minority girls in two contexts: an unstructured summertime setting and in the context of a structured 4-week community-based summer day camp program promoting physical activity. Data were analyzed using paired-sample t tests and repeated-measure analyses of variance with significance at the p < .05 level. Results evidenced no significant differences in total calories and fat consumed between the unstructured and structured settings. Participants exhibited significant increases in fruit consumption and physical activity and significant decreases in sedentary time of over 2 h/day and dairy consumption when engaged in structured summer programming. All improvements were independent of weight status and age, and African-American participants evidenced greater changes in physical activity during programming. The study concludes that structured, community-based summertime programming may be associated with fewer obesogenic behaviors in low-income urban youth and may be a powerful tool to address disparities in weight gain and obesity among high-risk samples.

Impact of the Balanced School Day on Glycemic Control in Children with Type 1 Diabetes

OBJECTIVE

The balanced school day (BSD) is an alternative elementary school schedule whereby children have 2 20-minute eating periods instead of 1 20-minute lunch, as is found in the traditional schedule (TS). We assessed the glycated hemoglobin (A1C) levels of children with type 1 diabetes in the TS vs. the BSD because 2 eating periods have the potential to impact blood glucose control.

METHODS

A1C levels representative of the summer months (SumA1C) and A1C levels occurring at least 3 months after the start of the school year (SchA1C) were obtained retrospectively. A parental survey of perceptions of lunch planning, activity levels and diabetes management at school was also completed.

RESULTS

Our sample included 97 students (TS=42, BSD=55). The mean age ± SD was 10.9±2.6 and 10.1±2.8 years in the TS and BSD, respectively (p=0.12). Sex distribution was not statistically different; 54% were female in TS vs. 36% in BSD; p=0.08. SumA1C was similar in the 2 groups (TS: 8.3±1.1% vs. BSD: 8.0±0.8%; p=0.08). There was a significant within-group increase from SumA1C to SchA1C in the BSD group only (p=0.001), with mean A1C values increasing from 8.0%±0.8% to 8.5%±1.0% in the BSD group compared to no significant increase in the TS group. Parental perceptions of lunch planning, physical activity and diabetes management were similar, regardless of school schedule.

CONCLUSIONS

Children with type 1 diabetes in the BSD appear to have worse diabetes control during the school year compared to the summer, which is not evident in children in the TS. Additional school supports may assist students in the BSD.

Seasonal changes in objectively measured sedentary behavior and physical activity in Japanese primary school children

BACKGROUND

The recent prevalence of obesity in Japanese children is much higher compared to 1980. The present study compared daily sedentary behavior (SB) and physical activity (PA) between the school year and summer vacation in Japanese primary school children.

METHODS

Participants were 98 Japanese boys (8.9 ± 1.8 years at baseline) and 111 girls (9.1 ± 1.8 years). SB and PA were measured in May (school term) and July/August (summer vacation), 2011. SB and PA were assessed using a triaxial accelerometer (Active style Pro HJA-350IT, Omron Healthcare) for 7 consecutive days. The average number of minutes spent in SB (no more than 1.5 metabolic equivalents (METs)), light intensity activity (LPA; more than 1.5 to less than 3.0 METs) and moderate-to-vigorous physical activity (MVPA; 3.0 METs or more), and step counts were calculated for each individual. Moreover, the determinants/moderators of changes in SB and PA were examined.

RESULTS

Daily SB was significantly higher in the summer vacation than in the school year for both boys and girls (p < 0.05). Ambulatory and total LPA and MVPA, non-ambulatory LPA and step counts were lower in summer vacation in both genders (p < 0.001). Moreover, non-ambulatory MVPA was significantly lower in the summer vacation than in the school year for girls (p < 0.001). The decrease in non-ambulatory MVPA in boys and increase in SB in girls were significantly lower in those who participated in sports compared to those who did not (p < 0.040 or p < 0.033). The change in SB for boys was significantly associated with having a TV in the bedroom (p < 0.022).

CONCLUSIONS

These findings show that primary school children in Japan are less active in the summer vacation, as indicated by both higher SB and lower LPA and ambulatory MVPA in both genders. Moreover, the seasonal change in non-ambulatory MVPA for Japanese children was affected by gender. This study also suggests that sports participation and bedroom TV ownership may moderate seasonal changes in PA and SB. The results emphasize the need to take summer vacation into account when planning interventions aimed at decreasing SB or increasing PA in Japanese children.

A Historical Review of Changes in Nutrition Standards of USDA Child Meal Programs Relative to Research Findings on the Nutritional Adequacy of Program Meals and the Diet and Nutritional Health of Participants: Implications for Future Research and the Summer Food Service Program

Background: The USDA child meal programs (CMPs) (National School Lunch Program (NSLP), School Breakfast Program (SBP), and Summer Food Service Program (SFSP) were established in 1946 (NSLP) and 1975 (SBP and SFSP) to improve the diet and nutritional health of US children. There is concern that participation in these programs may in fact be a contributor to the current childhood obesity epidemic. Objective: The purpose of this study was to determine if the CMPs are meeting their intended goal by reviewing the historical changes to nutrition standards of the CMPs in correspondence with the literature that examines the nutritional adequacy of meals served as part of these programs, as well as the dietary intakes and nutritional status of participants. Methods: Public Law and the Federal Register were reviewed and websites and online databases were systematically searched. Results: NSLP and SBP first underwent updates to the nutrition standards in 1994 and subsequently 2010, whereas SFSP last underwent modifications in 2000. The majority of data, all collected prior to 2010, demonstrate that meals served as part of the NSLP and SBP are not meeting nutrition standards. In addition, the dietary intakes of NSLP and SBP participants are high in calories, fat, saturated fat, and sodium, and low in fiber. Studies examining the weight status and other nutrition-related health outcomes of NSLP and SBP participants have produced mixed results. In contrast, no studies published in the peer-reviewed literature have been conducted examining the nutritional adequacy of SFSP meals or the dietary intakes or nutritional health of SFSP participants. There are public reports available on the nutritionally adequacy of SFSP meals, however, they are severely outdated (1988 and 2003). Due to this dearth of information, a case study on a sample SFSP menu from summer 2015 was conducted; results showed that the meals are high in carbohydrate and protein content and insufficient in vegetable servings. Conclusions: There is critical need for policy change that would enable updates to the SFSP nutrition standards to match those of the NSLP and SBP. In addition, strategies are needed to facilitate development of CMP menus that meet current nutrition standards. Finally, rigorously designed studies are needed to understand the direct impact of CMP participation on child diet and health, particularly the SFSP for which there is limited published data.

School Term vs. School Holiday: Associations with Children's Physical Activity, Screen-Time, Diet and Sleep

This cross-sectional study examined differences in children's health behaviors during school term (ST) versus school holiday (SH: June-July) and how associations changed when weather characteristics were considered. Children aged 5-18 years (n = 406) from a subtropical climate reported behaviors over 20 months. Multivariable regression models controlling for age, sex, race and body mass index z-score (BMIz) were used to examine associations between SH and each behavior. A second model included heat index, precipitation and daylight hours. Strenuous activity, moderate activity, total activity and TV viewing were significantly higher during SH than ST. After adjusting for weather characteristics, total activity remained significantly higher during SH, but the association with TV viewing was attenuated. Youth surveyed during high precipitation were significantly less likely to meet physical activity guidelines. There were no significant associations between SH and meeting sleep, physical activity or screen-time guidelines. Weather characteristics influenced associations between SH and youth's physical activity and TV viewing.

Weight-related behaviors when children are in school versus on summer breaks: does income matter?

BACKGROUND

Income disparities in US youth in academic achievement appear to widen during the summer because of discontinued learning among children from lower-income households. Little is known about whether behavioral risk factors for childhood obesity, such as diet and physical activity, also demonstrate a widening difference by income when children are out of school.

METHODS

Data from US children in grades 1-12 in the National Health and Nutrition Examination Survey 2003-2008 (N = 6796) were used to estimate screen time, moderate-to-vigorous physical activity (MVPA), and consumption of calories, vegetables, and added sugar. Linear regression was used to compare among children of households ≤185% and >185% poverty, as well as during the school year versus on school breaks.

RESULTS

Children surveyed during summer breaks consumed fewer vegetables (-0.2 cups/day) and more added sugar (+2.1 teaspoons/day), were more active (+4.6 MVPA minutes/day) and watched more television (+18 minutes/day). However, the nonsignificant interaction between school breaks and income indicated that lower-income students were not "less healthy" than higher-income students during the summer breaks.

CONCLUSION

Obesity-related risk factors were more prevalent during the summer and among lower-income youths, but the income disparity in these behaviors was not exacerbated when schools are not in session.

Seasonal variability in weight change during elementary school

OBJECTIVE

To examine seasonal variation in weight gain across elementary school (kindergarten-5th grade) among children who are healthy weight, overweight, or obese and from different racial and ethnic groups.

METHODS

The sample included 7,599 ethnically diverse students ages 5-7 years at baseline (Caucasian: 21.1%, Black: 36.2%, Hispanic: 26.0%, Asian 16.7%). Heights and weights were measured by school nurses at the beginning and end of each school year from kindergarten through the beginning of 5th grade.

RESULTS

Beginning the summer after 1st grade, all children demonstrated a pattern of standardized BMI (zBMI) increases during the summer (0.04 to 0.09) and zBMI decreases across the school years (-0.06 to 0.00; P<0.0001). Hispanic children and children who were overweight and obese exhibited this pattern in kindergarten while children of other ethnicities and with a healthy weight did not (P<0.0001).

CONCLUSIONS

Beginning the summer after 1st grade, a consistent pattern of relative weight gain during the summer months (Δ in BMI percentile=1.04) and weight loss during the school year (Δ in BMI percentile=-0.34) emerged. This pattern appeared earlier for children who were overweight, obese, or Hispanic. These findings suggest a need to better understand the causes of the problematic increases in weight during the summer.

School year versus summer differences in child weight gain: a narrative review

The causes of the current high prevalence of overweight and obesity among children are not clearly known. Schools have been implicated in the causal chain to high child obesity prevalence. Recent studies have compared school year versus summertime changes (herein called seasonal differences) in child adiposity or related phenomena. The most common seasonal pattern in six longitudinal descriptive studies was that overweight and obese children experienced accelerated gain in weight or some BMI indicator during the summer, whereas healthy weight children gained less or not at all. Four physical activity (PA) intervention studies demonstrated that school year fitness improvements were lost during the summer. One study showed that PA declined across the summer. Another study provided conflicting results of lower total energy expenditure in the summer, but no seasonal difference in total energy expenditure after adjusting for fat-free mass. This pattern of fairly rapid seasonal differences suggests that PA is the primary factor contributing to seasonal differences in weight or BMI, but the documented seasonal pattern in PA (i.e., higher in summer) does not support this relationship. Sleep duration has also been inversely related to child adiposity. Seasonal patterns in adiposity, PA, and sleep need to be clearly established separately for overweight and healthy weight children in further longitudinal research to provide a clear focus for national policy.