Puberty begins with a characteristic subcutaneous body fat mass in each sex

Objective: To observe whether there exists a characteristic body fat mass a t pubertal onset. Design: Longitudinal clinical follow-up (between ages of 10 and 15 y) with an annual visit in a sample of 469 children. They were grouped according to age of purbertal onset: boys with pubertal onset at the ages of 11 (n = 59 ), 12 (n = 88), 13 n = 89) and 14 y (n = 46), and girls with pubertal onset at the age of 10 (n = 68), 11 (n = 66), 12 (n = 37) and 13 (n = 16). Methods: Height, weight, upper arm circumference and four skinfold thicknes ses were recorded annually. In boys testicular volume index was measured, a nd genital development was assessed on the Tanner scale; in girls mammary d evelopment was measured also using the Tanner scale. The sum of four skinfo lds, body mass index, upper arm fat estimate and percentage body fat were c alculated. Results: Boys presented a positive relation between the age of pubertal ons et and body mass index (P < 0.001), which was not observed in girls. Body m ass index thus varied according to the onset of puberty in boys (P < 0.001) . but not in girls. The sum of four skinfolds, the upper arm fat estimate i ndex and the percentage of body fat mass did not differ according to age of pubertal onset either in girls (P = NS) or in boys (P = NS). The character istic adiposity of the puberty onset is progressively acquired during the p revious years in all the groups. Conclusions: Puberty seems to begin with a characteristic subcutaneous body fat mass that is independent of the age of onset. This study supports the hypothesis of a close link between maturation and the development of an ene rgy store in the form of adipose tissue in both sexes.