Nutritional conditions and the amount of body energy reserves play a critical role in regulating the onset of puberty. Thus, extreme situations of energy imbalance, ranging from malnutrition to obesity, are associated with alterations in pubertal timing. Although the mechanisms underlying this association remain largely unknown, recent research has unveiled the relevance of novel neurohormonal and molecular mechanisms in the metabolic control of puberty. This review summarizes some of those important advancements, including the crucial roles of neuroendocrine pathways involving the hypothalamic kisspeptin neurons and the metabolic hormones leptin, insulin, and ghrelin in the tight coupling of body energy status and puberty onset. We will also review here the integrative function of key cellular energy sensors, such as mTOR, AMPK, and SIRT1, in this setting.