The BMI low point is between ages four and seven.
"Earlier rebound age correlates with greater likelihood to become obese adults," said Jennifer Jaworski of the University of Cincinnati College of Medicine and lead author of the study.
The results of the study were presented at the ongoing American Heart Association meet.
The study investigated BMI rebound age in 308 children, 158 boys and 150 girls, beginning at age three and looked at adverse cardiovascular risk effects at age seven.
"Obesity is a problem that develops early in childhood and has adverse cardiovascular consequences early in childhood," said Thomas R. Kimball, senior author of the study.
Kimball said it was important for physicians to measure BMI and BMI rebound age in younger children as well as adolescents.
"These problems of overweight and cardiac risk factors begin at an early age, not just in teenage or adult years. As a physician and parent, I'd rather deal with these issues before the habits are set. The crux of the matter is when these habits are set in childhood, they are difficult to break. It's not just the child's problem, but becomes a family issue."