Which hormone is released during exercise that aids muscle growth and fat metabolism?

Which hormone is released during exercise that aids muscle growth and fat metabolism? The answer is growth hormone, or GH.

GH is a peptide hormone released by somatotropic cells in the anterior pituitary. Vigorous exercise is one stimulus for its pulsatile secretion, alongside deep sleep, fasting, and several hypothalamic signals. GH promotes lipolysis, helping release fatty acids from adipose tissue, and supports growth-related processes partly by stimulating production of insulin-like growth factor 1, or IGF-1.

The popular claim that an exercise-related GH surge automatically builds large, stronger muscles is too simple. Muscle growth depends on the overall training stimulus, nutrition, recovery, and many signaling pathways. Studies of supplemental GH in healthy adults have found increases in lean mass or reductions in fat in some settings, but not a reliable improvement in strength or athletic performance.

GH is also not the same as insulin, cortisol, or thyroid hormone. It is medically important in childhood growth and adult deficiency, while non-prescribed use for performance enhancement is prohibited by major sporting organizations and carries health risks.