When people hear the term growth hormone, they often think only about childhood growth and height. However, growth hormone continues to play an important role throughout adult life.
In adults, it helps support muscle mass, body composition, metabolism, bone health, physical performance, and general well-being.
What Is Growth Hormone?
Growth hormone, or GH, is a peptide hormone produced by the pituitary gland, a small gland located at the base of the brain.
It is released in pulses throughout the day, with some of the largest releases occurring during deep sleep.
Growth hormone also stimulates the liver and other tissues to produce insulin-like growth factor 1, or IGF-1. Many of the effects of growth hormone are mediated through IGF-1.
What Does Growth Hormone Do During Childhood?
During childhood and adolescence, growth hormone is essential for:
- Normal growth in height
- Bone development
- Muscle development
- Protein production
- Healthy body composition
A significant deficiency during childhood may result in slower growth and reduced adult height.
However, the role of growth hormone does not stop when a person finishes growing.
What Does Growth Hormone Do in Adults?
Adults no longer need growth hormone to grow taller, but it continues to support several important functions. These are physiological roles — they describe what the hormone does in the body, not a treatment on offer.
The growth hormone (GH) to IGF-1 pathway: how GH from the pituitary gland acts through the liver and IGF-1 to support muscle, bone, metabolism, and tissue maintenance in adults.
Muscle and body composition. Growth hormone supports protein metabolism and the maintenance of lean body tissue. It is part of the hormonal environment that supports muscle health, but it is not a substitute for resistance training or adequate protein intake.
Body fat. Growth hormone helps the body mobilize stored fat and use it for energy. In significant deficiency, adults may develop more abdominal fat alongside reduced lean muscle, sometimes even when overall body weight does not change much.
Bone health. Growth hormone and IGF-1 contribute to bone turnover and bone mineral density. Long-term deficiency may be associated with lower bone density and a higher fracture risk, particularly with age.
Metabolism. Growth hormone helps regulate how the body processes fat, protein, and glucose. Importantly, the goal is not to maximize growth hormone — excessive levels can reduce insulin sensitivity and raise blood glucose. The aim is an appropriate level, not the highest possible one.
Physical performance and recovery. Growth hormone contributes to tissue maintenance and protein synthesis. Adults with true deficiency may notice reduced exercise capacity and slower recovery — although the same symptoms are commonly caused by poor sleep, low testosterone, thyroid problems, anemia, inadequate nutrition, or overtraining.
Does Growth Hormone Decline With Age?
Yes. Growth hormone secretion is highest during puberty and early adulthood and gradually declines with age. This is a normal physiological process.
Crucially, this normal age-related decline is not the same as true adult growth hormone deficiency, which is usually more significant and related to a problem affecting the pituitary gland or hypothalamus. How genuine deficiency is distinguished from normal aging — and how it is tested — is covered in our companion article, Low Growth Hormone in Adults: Symptoms, Causes, and Testing.
The Takeaway
Growth hormone is not only important during childhood. In adults, it continues to support muscle function, body fat regulation, metabolism, bone health, and physical performance.
Growth hormone naturally declines with age, but the goal is never to maximize it. The aim is to maintain safe and appropriate hormone activity based on the individual’s age, symptoms, health status, and clinical findings.
Any evaluation or treatment should be individualized and medically supervised. Growth hormone replacement is reserved for a properly documented deficiency, not for normal age-related decline.
