Timing of Adiposity Rebound
Adiposity rebound (AR) is used as an indicator to predict obesity in adults. Previous studies about AR in the U.S. were based on local data; therefore, the generalizability of study results is limited. The purpose of this study was to identify the timing of AR for U.S. children using a national survey data set, the National Health and Nutrition Examination Survey (NHANES). Combined data of NHANES 1999–2008 were used to estimate the national level of this critical period for U.S. children developing obesity. Data of 8,813 children 2 to 10 years of age were analyzed. Mean body mass index was estimated using the survey sample analysis method. Visual inspection method was employed to examine the timing of AR. Gender and race/ethnicity differences in AR were identified at an early age. AR occurred earlier in girls and in Non-Hispanic African-American children than in Non-Hispanic Caucasian children. Differences in timing for AR by gender and race/ethnicity should be considered in planning early and timely intervention efforts to prevent childhood obesity.
The prevalence of overweight children 2 to 19 years of age in the U.S. has increased approximately 3 to 4 times in the last three decades (Centers for Disease Control and Prevention [CDC], 2009a). Overweight prevalence has varied by racial/ethnic group and has been more prevalent among racial/ethnic minority children (Ogden, Carroll, & Flegal, 2008). To reduce obesity prevalence and prevent obesity-associated health problems, it is important to identify children at risk for future obesity and prevent obesity in early life.
One strategy to predict adult obesity is related to identification of the timing of adiposity rebound (AR). Researchers have shown that AR is a critical period for the development of adiposity that persists into later life (Adair, 2008; Dietz, 1994; Drohan, 2002; He & Karlberg, 2001; Rolland-Cachera et al., 1987; Rolland-Cachera, Deheeger, Maillot, & Bellisle, 2006). Usually, children's body mass index (BMI) increases during the first year of life. After that, BMI gradually decreases until it reaches the lowest point, around 6 years of age, before increasing again (Eisenmann, Heelan, & Welk, 2004; Rolland-Cachera et al., 1984, 2006; Williams, 2005; Williams, Davie, & Lam, 1999; Williams & Goulding, 2008).
Age that the lowest point of BMI is reached is the start point of AR (Rolland-Cachera et al., 1984, 2006). A number of studies have shown that children who experience early age of AR (less than or equal to 5 to 5.5 years) are at risk of being overweight adolescents (Rolland-Cachera et al., 1984) and adults (Freedman, Kettel Khan, Sedula, Srinivasan, & Berenson, 2001; Pan et al., 2009; Whitaker, Pepe, Wright, Seidel, & Dietz, 1998; Williams et al., 1999) compared with children with late age of AR (greater than or equal to 7 years). Early age of AR is also associated with the development of type 2 diabetes (Bharagava et al., 2004; Eriksson, Forsén, Tumilehto, Osmand, & Barker, 2003).
The age of AR among U.S. children has been studied, but no research has used national data to estimate the age of AR. Previous studies about the timing of AR in the U.S. were based on local data and specific race/ethnicities (Freedman et al., 2001; Skinner, Bounds, Carruth, Morris, & Ziegler, 2003; Whitaker et al., 1998). Thus, the generalizability of results from previous studies of AR is limited. Therefore, the purpose of this study is to identify the timing of AR for U.S. children using a national survey data set, the National Health and Nutri tion Examination Survey (NHANES). NHANES represents a diverse sample of the civilian, non-institutionalized U.S. population that allows identification of subgroups of children who display different timings of AR by gender and race/ethnicity. These diverse AR timings could help health care providers develop a better understanding of this important period in the development of obesity by U.S. children. This information would also be useful in designing gender- and race/ethnicity-specific obesity prevention strategies for early-aged children.
Abstract and Introduction
Abstract
Adiposity rebound (AR) is used as an indicator to predict obesity in adults. Previous studies about AR in the U.S. were based on local data; therefore, the generalizability of study results is limited. The purpose of this study was to identify the timing of AR for U.S. children using a national survey data set, the National Health and Nutrition Examination Survey (NHANES). Combined data of NHANES 1999–2008 were used to estimate the national level of this critical period for U.S. children developing obesity. Data of 8,813 children 2 to 10 years of age were analyzed. Mean body mass index was estimated using the survey sample analysis method. Visual inspection method was employed to examine the timing of AR. Gender and race/ethnicity differences in AR were identified at an early age. AR occurred earlier in girls and in Non-Hispanic African-American children than in Non-Hispanic Caucasian children. Differences in timing for AR by gender and race/ethnicity should be considered in planning early and timely intervention efforts to prevent childhood obesity.
Introduction
The prevalence of overweight children 2 to 19 years of age in the U.S. has increased approximately 3 to 4 times in the last three decades (Centers for Disease Control and Prevention [CDC], 2009a). Overweight prevalence has varied by racial/ethnic group and has been more prevalent among racial/ethnic minority children (Ogden, Carroll, & Flegal, 2008). To reduce obesity prevalence and prevent obesity-associated health problems, it is important to identify children at risk for future obesity and prevent obesity in early life.
One strategy to predict adult obesity is related to identification of the timing of adiposity rebound (AR). Researchers have shown that AR is a critical period for the development of adiposity that persists into later life (Adair, 2008; Dietz, 1994; Drohan, 2002; He & Karlberg, 2001; Rolland-Cachera et al., 1987; Rolland-Cachera, Deheeger, Maillot, & Bellisle, 2006). Usually, children's body mass index (BMI) increases during the first year of life. After that, BMI gradually decreases until it reaches the lowest point, around 6 years of age, before increasing again (Eisenmann, Heelan, & Welk, 2004; Rolland-Cachera et al., 1984, 2006; Williams, 2005; Williams, Davie, & Lam, 1999; Williams & Goulding, 2008).
Age that the lowest point of BMI is reached is the start point of AR (Rolland-Cachera et al., 1984, 2006). A number of studies have shown that children who experience early age of AR (less than or equal to 5 to 5.5 years) are at risk of being overweight adolescents (Rolland-Cachera et al., 1984) and adults (Freedman, Kettel Khan, Sedula, Srinivasan, & Berenson, 2001; Pan et al., 2009; Whitaker, Pepe, Wright, Seidel, & Dietz, 1998; Williams et al., 1999) compared with children with late age of AR (greater than or equal to 7 years). Early age of AR is also associated with the development of type 2 diabetes (Bharagava et al., 2004; Eriksson, Forsén, Tumilehto, Osmand, & Barker, 2003).
The age of AR among U.S. children has been studied, but no research has used national data to estimate the age of AR. Previous studies about the timing of AR in the U.S. were based on local data and specific race/ethnicities (Freedman et al., 2001; Skinner, Bounds, Carruth, Morris, & Ziegler, 2003; Whitaker et al., 1998). Thus, the generalizability of results from previous studies of AR is limited. Therefore, the purpose of this study is to identify the timing of AR for U.S. children using a national survey data set, the National Health and Nutri tion Examination Survey (NHANES). NHANES represents a diverse sample of the civilian, non-institutionalized U.S. population that allows identification of subgroups of children who display different timings of AR by gender and race/ethnicity. These diverse AR timings could help health care providers develop a better understanding of this important period in the development of obesity by U.S. children. This information would also be useful in designing gender- and race/ethnicity-specific obesity prevention strategies for early-aged children.
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