Critical body fat percentage required for puberty onset: the Taiwan Pubertal Longitudinal Study

Prepubescent body fat percentage (BFP) is associated with puberty onset; however, the association between the timing of puberty onset and BFP remains unclear. This study aimed to determine whether and how the timing of puberty onset is associated with various anthropometric measures, and to investigate the critical time period of the BFP transition before and after puberty.

The Taiwan Pubertal Longitudinal Study (TPLS) has a multicenter, population-based prospective cohort and was established in July 2018 at 4 pediatric departments. We included girls aged 6-14 years and boys aged 9-17 years evaluated as having puberty onset and excluded those with precocious puberty diagnosis. The anthropometric measures were collected every 3 months. The main outcome was age at puberty onset. Data were analyzed between July 2018 and September 2020.

For 153 girls and 83 boys, BFP was significantly related to puberty onset for girls. Longitudinal analysis revealed that BFP in the girls was reduced to less than 18% 6 months before puberty and rapidly increased by 2.85% over 3 months, then exceeding 20% before puberty onset. After puberty onset, BFP was no longer lower than 22%.

BFP is an essential predictor of age at puberty onset. BFP first decreases and then begins to increase 3-6 months before puberty in girls. Parents and schools could monitor the BFP of prepubescent girls every 6 months to predict puberty onset.