Identifying Patterns of BMI Development and Associated Behavioral, Social, Environmental, Genetic, and Biological Factors for Children from 3-10 Years

夏季(即5月至8月)是BMI加速增长的时期，导致儿童肥胖症的增加。二 理论可能可以解释夏季BMI加速上升的原因。昼夜节律模型(CCRM)假设 夏季BMI的增加是由光-暗周期变化的生物学驱动的，而BMI的增加在 夏天白天更长，体重增加超过身高增加，冬季则减速 白天变短了，身高的增加超过了体重的增加。结构化天数假说(SDH)提出 BMI在夏季的加速增长是由于取消了有组织的上学日(即，学校与 夏季不上学)，这会影响儿童参与关键的肥胖行为(体力活动， 久坐/看电视的时间、饮食摄入和睡眠)。整个学年的休息时间(1周秋假，2周 冬假、一周春假)也可能导致BMI加速上升。当前加速的BMI增益研究 完全集中在暑期和学年的比较上。这些研究在春季(5月)对儿童进行测量 夏季之前)和秋季(夏季之后的8月)，只允许比较 夏季的3个月和一年中的其他9个月。它不允许测量减速 CCRM预测的冬季BMI增长，也没有考虑到BMI增长的加速测量 在SDH预测的秋季、冬季和春假期间。这是我们对 儿童肥胖何时发生以及如何治疗。这项研究将通过确定 儿童身高、体重和BMI增长的加速和减速的月度模式 相关的行为、社会、环境和生物决定因素。我们将招募3个队列(3K， 对200名儿童(共600名)进行队列序贯设计。 我们将每月收集BMI；肥胖行为(体力活动、久坐/屏幕时间、饮食摄入量和 睡眠)；以及三年内的社会、环境和生物信息 对于每个队列。队列序贯设计将使我们能够绘制出BMI的发展和季节性变化 从3K到五年级的行为。我们将实现以下具体目标：目标1：确定身高的月变化， 体重和BMI在一大群不同的儿童(3K到5年级，N=600)中发生变化。目标2：检查 身高、体重和BMI的月型变化与季节(秋、冬、春、夏)的关系 肥胖行为的模式。目标3探索性：考察社会、环境和生物之间的关系 具有行为模式以及身高、体重和BMI z分数变化的因素。这个项目意义重大 因为它填补了一个主要的空白(每月体重指数z得分增加的模式)，在关于发展的知识 儿童肥胖是一种普遍的公共健康危机。这个项目是创新的，因为它将是第一个 每月测量体重指数增长的研究以及与之相关的行为、社会、环境和生物 预测加速/减速BMI增益的确定。

Summer (i.e., May-August) is a period of accelerated BMI gain that leads to increases in childhood obesity. Two theories may explain accelerated summer BMI gain. The Circadian and Circannual Rhythm Model (CCRM) posits that BMI gain during summer is biologically driven by the shifting light-dark cycle, with BMI gain accelerating during the summer when days are longer and weight gain outpaces height gain and decelerating during the winter when days are shorter and height gain outpaces weight gain. The Structured Days Hypothesis (SDH) proposes that accelerations in BMI gain during the summer are due to the removal of the structured school day (i.e., school vs no school during summer) which influences children’s engagement in key obesogenic behaviors (physical activity, sedentary/screen time, dietary intake, and sleep). Breaks throughout the school year (1-week fall break, 2-week winter break, 1-week spring break) may also cause accelerated BMI gain. Current accelerated BMI gain research is focused exclusively on summer vs. school year comparisons. These studies measure children in the spring (May prior to summer) and fall (August following summer) exclusively, allowing only for comparisons of BMI gain between the 3 months of summer and the other 9 months of the year. It does not allow for the measure of decelerations in BMI gain predicted by the CCRM during the winter, nor does it allow for the measure of accelerations in BMI gain during the fall, winter, and spring breaks predicted by the SDH. This is a critical limitation in our understanding of WHEN childhood obesity occurs and HOW to treat it. This study will overcome these limitations by identifying monthly patterns in the accelerations and decelerations of children’s height, weight, and BMI gain and the associated behavioral, social, environmental, and biological determinates. We will recruit 3 cohorts (3K, Kindergarten, and Second grade) of 200 children (600 children in total) to participate in a cohort-sequential design. We will collect BMI monthly; obesogenic behaviors (physical activity, sedentary/screen time, dietary intake, and sleep) in the spring, summer, fall, and winter; and social, environmental, and biological information over three years for each cohort. The cohort-sequential design will allow us to map BMI development and seasonal shifts in behaviors 3K to 5th grade. We will accomplish the following specific aims: Aim 1: Identify monthly variations in height, weight, and BMI change in a large and diverse cohort of children (3K to 5th grade, N=600). Aim 2: Examine the relationship between monthly patterns of height, weight, and BMI change with seasonal (fall, winter, spring, summer) patterns in obesogenic behaviors. Aim 3 Exploratory: Examine the relationship of social, environmental, and biological factors with patterns in behaviors and variations in height, weight, and BMI z-score change. This project is significant because it fills a major gap (monthly patterns of BMI z-score gain) in the knowledge about the development of childhood obesity, a widespread public health crisis. This project is innovative because it will be among the first studies to measure BMI gain monthly along with the associated behavioral, social, environmental, and biological determinates that predict accelerated/decelerated BMI gain.