### Abstract

- Top of page
- Abstract
- Introduction
- Research Methods and Procedures
- Results
- Discussion
- Acknowledgments
- References

*Objective:* To develop a probability chart of adult overweight based on childhood body mass index (BMI) values and to evaluate the BMI change during the BMI rebound period during childhood, in different populations, with the use of risk function curves.

*Research Methods and Procedures:* A longitudinal growth study of 3650 full-term healthy Swedish children followed from birth to 18 years of age. Weight and height values of our subjects were obtained.

*Results:* A probability chart for reaching a BMI > 23 kg/m^{2} at 18 years of age was constructed for boys and girls. For example, a BMI of 18 kg/m^{2} at 4 years of age is associated with 0.70 probability of attaining a BMI > 23 kg/m^{2} at 18 years of age in boys; a BMI of 16 kg/m^{2} at 4 years of age leads to 0.40 probability of having a BMI > 23 kg/m^{2} at 18 years of age in girls. Children with an obvious BMI rebound before 8 years of age have a high risk of being overweight at 18 years of age. There is a clear trend of BMI increase from the 1970s to the 1990s in U.S. children from a parallel dataset, and Hispanic children are at the highest risk of adult overweight.

*Discussion:* The probability chart for adult overweight developed here provides a functional method of defining childhood obesity that is based on the risk of long-term ill health rather than on a certain statistical cut-off point. It will help pediatricians or healthcare workers identify those children who are at a high risk of becoming overweight in adulthood, which will allow clinical intervention at younger ages.

### Introduction

- Top of page
- Abstract
- Introduction
- Research Methods and Procedures
- Results
- Discussion
- Acknowledgments
- References

The prevalence of obesity is increasing dramatically worldwide in both developed and developing countries (1). Moreover, because the problem seems to be increasing rapidly in children as well as in adults, the health consequence of obesity will only be fully apparent in the next decade or so. Action for the prevention and management of obesity is urgently required on a global basis. Obesity and overweight are related to many diseases in adulthood, such as diabetes, hypertension, dyslipidemia, and cardiovascular diseases (2, 3). Although difficult to treat once developed, obesity and its risk seem preventable through early intervention. Because childhood obesity may persist into adulthood (4, 5, 6), it is necessary to identify high-risk individuals for clinical intervention at an early age. Research, based on a large longitudinal growth study (7), using childhood body mass index (BMI) to predict adult obesity (BMI > 25 kg/m^{2}), has previously been published. However, because the risk factors for obesity-related disorders start to increase from about a BMI of 23 kg/m^{2} in most populations (8, 9, 10), setting a BMI goal of 23 kg/m^{2} would be appropriate from a prevention point of view. The aims of this study were to produce the probability charts for adult overweight based on a cut-off point of BMI > 23 kg/m^{2} and to explore how the risk of adult overweight changes during the BMI rebound period in different ethnic groups and generations.

### Discussion

- Top of page
- Abstract
- Introduction
- Research Methods and Procedures
- Results
- Discussion
- Acknowledgments
- References

A set of practical and simple probability charts for overweight at 18 years of age is presented based on the large longitudinal growth study worldwide, consisting of 3650 full-term babies followed from birth to 18 years of age. Obvious BMI rebound before 8 years of age associated with a high risk of adult overweight was also shown in our study.

The prediction of adulthood obesity during the pediatric years is urgently needed because of the dramatic increasing prevalence of adult obesity (18) and the relatively unsuccessful treatment of obese adults (19). Because obesity in childhood is associated with less morbidity than in adulthood, evaluation of childhood obesity should be based on the risk of short-term or long-term ill health, rather than on a certain statistical cut-off point (20). Very little data is available linking age-specific childhood BMI values to the risk of short-term or long-term ill health (21). A set of prediction charts for obtaining a BMI > 23 kg/m^{2} at 18 years of age was created for boys and girls separately in our study. These charts provide a novel and easy way of estimating the risk of young adults (18 years of age) being overweight based on the individual BMI value from 3 years of age and older. The data used in our study came from a large, longitudinal, population-based growth study of Swedish children followed from birth to 18 years of age. This study represents the largest current longitudinal growth study worldwide. The representativeness and uniqueness of this data set have been discussed in previous publications (7, 14).

Another attempt to predict adult obesity is related to the nadir of the BMI-for-age curve, which usually occurs between 3 and 8 years of age. Rolland-Cachera et al. (13) reported that most children follow the percentile line pattern of the BMI chart; a decrease followed by a rise in BMI values during this period. The corresponding time of the minimum BMI value during this period is called the adiposity rebound age; the earlier the adiposity rebound, the greater the risk of adult obesity (22). We depict BMI change during this period using the probability chart developed in our study. It clearly can be seen that a group with a rebound before 8 years of age will have a higher risk of adult obesity, reaching a BMI > 23 kg/m^{2} at 18 years of age. Therefore, maintaining less increase in BMI, or following the same risk curve before 8 years of age, is important to prevent overweight at 18 years of age.

The secular trend of BMI increase in the U.S. population can also be clearly seen when the BMI level in the 1970s is compared with that in the 1990s. Today, 5% of U.S. children are above 70% risk of adult overweight at 5 years of age, and Hispanic children are at the highest risk of adult overweight. Because the long-term treatment programs developed for obese children are relatively expensive and time-consuming, children who are at a high risk of adult overweight should be treated as the target group for intervention.

The global extrapolation of current results, which are based on a Swedish sample, might require further discussion. With the dramatic increase in overweight and obesity worldwide, it is possible that the secular changes over time in Sweden, as well as elsewhere, could have or may change the BMI prediction model presented here.

Because the risk of obesity-related disorders starts to increase from a BMI of 23 kg/m^{2} in most populations, a BMI goal of 23 kg/m^{2} would be ideal from a preventative point of view. A set of practical, simple, and novel probability charts for adult overweight are reported here. These charts will provide a useful tool for pediatricians to identify those children who are at a high risk of becoming overweight in adulthood so that clinical intervention can be started as early as possible.