While obesity has been shown to bring on puberty earlier in girls, a study finds the opposite trend for overweight boys.

In a study published in the Archives of Pediatrics and Adolescent Medicine, researchers tracked the height and weight growth of 401 boys born in 1991. Among the roughly 28 percent of boys whose weight was consistently highest through early and middle childhood, 14 percent appeared not to have begun pubertal changes at 11 1/2 -- a rate nearly twice as high as that seen among the slimmest group of boys. Among the whole group, 12.2 percent were prepubertal at 11 1/2.

The authors said their findings offer insights into the differing processes that push girls and boys toward sexual maturation, as well as how obesity might disrupt that process in boys. They found that either of two hormones -- the digestive hormone leptin and the sex hormone estradiol -- appear to be high in obese preadolescent boys, which might delay the onset of puberty.


Exercising with the stars

Would you like to work out with country singer Julianne Hough? In "Cardio Ballroom" (Anchor Bay, $15), Hough shares some of the dance moves she taught celebrities as their coach on "Dancing With the Stars." She offers tutorials on basics such as the cha-cha and ball change.