There is no consistent result in the relationship between obesity and timing of pubertal onset in boys .
Obesity may contribute to early onset of puberty in girls , while in boys , there is insufficient data .
This systematic review and meta- analysis examined the associations between obesity and puberty timing based on scientific evidence .
Infancy weight gain predicts childhood body fat and age at menarche in girls.
CONTEXT Rapid postnatal weight gain has been associated with subsequent increased childhood adiposity . However , the contribution of rapid weight gain during specific infancy periods is not clear . OBJECTIVE We aim ed to determine which periods of infancy weight gain are related to childhood adiposity and also to age at menarche in UK girls . DESIGN , SETTING , AND PARTICIPANTS A total of 2715 girls from a prospect i ve UK birth cohort study participated in the study . MAIN OUTCOME MEASURES Routinely measured weights and lengths at ages 2 , 9 , and 19 months were extracted from the local child health computer data base . Body composition was assessed by dual-energy x-ray absorptiometry at age 10 yr , and age at menarche was assessed by question naire ( categorized into three groups : < 12.0 , 12.0 - 13.0 , and > 13.0 yr ) . RESULTS Faster early infancy weight gain between 0 and 2 months and also 2 to 9 months were associated with increased body fat mass relative to lean mass at age 10 yr and also with earlier age at menarche . Each + 1 unit gain in weight sd score between 0 and 9 months was associated with an odds ratio ( 95 % confidence interval ) = 1.48 ( 1.27 - 1.60 ) for overweight ( body mass index > 85th centile ) at 10 yr , and 1.34 ( 1.21 - 1.49 ) for menarche at less than 12 yr . In contrast , subsequent weight gain between 9 and 19 months was not associated with later adiposity or age at menarche . CONCLUSIONS In developed setting s , rapid weight gain during the first 9 months of life is a risk factor for both increased  childhood adiposity and early menarche in girls
There is no consistent result in the relationship between obesity and timing of pubertal onset in boys .
Obesity may contribute to early onset of puberty in girls , while in boys , there is insufficient data .
This systematic review and meta- analysis examined the associations between obesity and puberty timing based on scientific evidence .