Insulin and Growth Hormone Balance: Implications for Obesity

Disruption of endocrine hormonal balance (i.e., increased levels of insulin, and reduced levels of growth hormone, GH) often occurs in pre‐obesity and obesity. Using distinct intracellular signaling pathways to control cell and body metabolism, GH and insulin also regulate each other’s secretion to maintain overall metabolic homeostasis. Therefore, a comprehensive understanding of insulin and GH balance is essential for understanding endocrine hormonal contributions to energy storage and utilization. In this review we summarize the actions of, and interactions between, insulin and GH at the cellular level, and highlight the association between the insulin/GH ratio and energy metabolism, as well as fat accumulation. Use of the [insulin]:[GH] ratio as a biomarker for predicting the development of obesity is proposed. Insulin and GH are counter-regulatory hormones in terms of glucose and lipid metabolism, but act synergistically in protein metabolism. They also mutually regulate the secretion of each other, forming a complex regulatory network.The balance between insulin and GH is associated with substrate and energy metabolism. In obesity, the hormonal imbalance (high insulin and low GH) promotes further fat accumulation.Clinical data from various physiological and pathophysiological conditions with insulin and GH changes indicate that the [insulin]:[GH] ratio correlates negatively with energy expenditure and correlates positively with fat accumulation.The [insulin]:[GH] ratio may serve as a biomarker for monitoring and predicting the development of obesity. Modulation of insulin–GH balance is a promising target for managing obesity.