Summer effects on body mass index (BMI) gain and growth patterns of American Indian children from kindergarten to first grade: a prospective study

Jianduan Zhang,Mary Story,Bonnie Holy Rock,John H Himes,Mary Smyth,Peter J Hannan,Chrisa Arcan

doi:10.1186/1471-2458-11-951

Abstract

BackgroundOverweight and obesity are highly prevalent among American Indian children, especially those living on reservations. There is little scientific evidence about the effects of summer vacation on obesity development in children. The purpose of this study was to investigate the effects of summer vacation between kindergarten and first grade on growth in height, weight, and body mass index (BMI) for a sample of American Indian children.MethodsChildren had their height and weight measured in four rounds of data collection (yielded three intervals: kindergarten, summer vacation, and first grade) as part of a school-based obesity prevention trial (Bright Start) in a Northern Plains Indian Reservation. Demographic variables were collected at baseline from parent surveys. Growth velocities (Z-score units/year) for BMI, weight, and height were estimated and compared for each interval using generalized linear mixed models.ResultsThe children were taller and heavier than median of same age counterparts. Height Z-scores were positively associated with increasing weight status category. The mean weight velocity during summer was significantly less than during the school year. More rapid growth velocity in height during summer than during school year was observed. Obese children gained less adjusted-BMI in the first grade after gaining more than their counterparts during the previous two intervals. No statistically significant interval effects were found for height and BMI velocities.ConclusionsThere was no indication of a significant summer effect on children's BMI. Rather than seasonal or school-related patterns, the predominant pattern indicated by weight-Z and BMI-Z velocities might be related to age or maturation.Trial registrationBright Start: Obesity Prevention in American Indian Children Clinical Trial Govt ID# NCT00123032

Highlights

Overweight and obesity are highly prevalent among American Indian children, especially those living on reservations
The study indicated that American Indian children aged 6-17 years from rural school districts on or near reservations bear the burden of excess weight relative to other racial and ethnic groups, with a combined prevalence of overweight and obesity up to 53.8% [3], 2-3 times higher than the national average [4,5]
We investigated the effects of summer vacation between kindergarten and first grade on growth in height, weight, and body mass index (BMI) for a sample of American Indian Children participating in a school-based intervention program targeting prevention of excessive weight gain

Summary

Introduction

Overweight and obesity are highly prevalent among American Indian children, especially those living on reservations. The purpose of this study was to investigate the effects of summer vacation between kindergarten and first grade on growth in height, weight, and body mass index (BMI) for a sample of American Indian children. The study indicated that American Indian children aged 6-17 years from rural school districts on or near reservations bear the burden of excess weight relative to other racial and ethnic groups, with a combined prevalence of overweight and obesity up to 53.8% [3], 2-3 times higher than the national average [4,5]. Type 2 diabetes, long considered an adult illness, is becoming more common among American Indian children aged 10 years and older [8]. A recent study concluded that obesity in childhood is a primary factor contributing to increased rates of premature death from endogenous causes in American Indian populations [9]

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