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STUDY: Body fat levels during middle childhood are causally implicated in earlier timing of puberty among white girls
JOURNAL: Pediatrics 2003;111:815-821.
AUTHORS: Dr. Davison
ABSTRACT: Girls who have more body fat at age 5 tend to be closer to puberty at age 9 than other 9-year-old girls with less body fat. Girls who have large increases in body fat between the ages of 5 and 9 also tend to reach puberty at an earlier age.
COMMENTARY: The study findings suggest that weight control efforts may need to start as early as preschool.
Some experts believe that the rising rate of obesity among U.S. children has spurred early maturation. On average, girls are starting to show the first signs of breast development at ages 8 and 9, a year earlier than 20 years ago, according to the report in the journal Pediatrics.
Dr. Davison's team evaluated 181 girls at the age of 5, 7 and 9 years. All the girls underwent weight and body fat measurements, and at age 9 had pubertal development assessed. All the girls were white and from families with a median annual income that ranged from $35,000 to $50,000.
"Girls with higher percent body fat at 5 years, and girls with higher percent body fat, higher BMI percentile, or larger waist circumferences at 7 years, were more likely to be classified with earlier pubertal development at 9 years," the authors write.
Girls who gained the highest percentage of body fat between the ages of 5 and 9, and those who saw the largest increase in their waist size between the ages of 7 and 9 were also more likely to show signs of puberty onset at age 9, the study indicates. Overall, 30% of the girls were overweight and 56% showed the first signs of breast development by age 9.
"This study indicates that body fat levels during middle childhood are causally implicated in earlier timing of puberty among white girls," the authors conclude. "
The practical implications of these findings emphasize the need for implementation of early prevention and treatment programs for childhood overweight, beginning as early as the preschool period," they add.