Final answer:
The critical amount of body fat is necessary for successful reproduction during puberty as it allows for the release of leptin and thymosins, which are crucial for the production of sex hormones such as estrogen and testosterone.
Step-by-step explanation:
The rush of hormonal activity associated with puberty seems to depend on reaching a critical amount of body fat necessary for successful reproduction. This critical body fat is essential because adipose tissue releases a hormone called leptin, which is necessary for the production of estrogens and progesterone. Without sufficient body fat, leptin cannot be released, hindering the production of these hormones that are crucial for the maturation of the reproductive system and development of secondary sexual characteristics.
Additionally, body fat is implicated in the release of thymosins, which are necessary to produce gonadotropin-releasing hormone (GnRH) and gonadotropins. These hormones from the hypothalamus and pituitary gland stimulate the testes or ovaries to start producing sex hormones like testosterone and estrogen during puberty, leading to reproductive maturity. Thus, body fat plays a significant role in the hormonal regulation that triggers puberty.