Growth Hormone

What growth hormone does and why it declines

Growth hormone (GH), also called somatotropin, is a 191-amino-acid peptide released by the anterior pituitary gland. It drives cell repair, fat metabolism, muscle protein synthesis, and bone turnover. GH doesn't act alone: most of its peripheral effects are mediated through insulin-like growth factor 1 (IGF-1), which the liver produces in response to GH pulses.

GH secretion peaks during puberty, then drops roughly 14% per decade after age 30. By 60, most people produce less than half of what they did at 25. This progressive decline, sometimes called somatopause, overlaps with rising body fat, shrinking muscle mass, thinning bones, and slower recovery. Whether lower GH causes these changes or simply accompanies them is still debated.

The GH-IGF-1 longevity paradox

Here's the uncomfortable truth about growth hormone and aging: the evidence points in two directions at once.

In animal models, reducing GH or IGF-1 signaling consistently extends lifespan. Ames dwarf mice, which lack functional GH, live 40-60% longer than normal littermates. The Laron syndrome population in Ecuador, carrying a GH receptor defect that produces near-zero IGF-1 levels, shows almost no cancer and virtually no diabetes, though their overall lifespan doesn't clearly exceed that of unaffected relatives ^[1].

On the other hand, adults with untreated GH deficiency from pituitary disease have higher cardiovascular mortality, more visceral fat, worse lipid profiles, and reduced quality of life ^[2]. And the TRIIM trial (2019) found that a combination of recombinant GH, DHEA, and metformin reversed epigenetic age by roughly 2.5 years in 9 healthy men aged 51-65, while regenerating thymic tissue ^[3].

The likely resolution: there's an optimal range. Too much GH accelerates aging and cancer risk (as seen in acromegaly). Too little, especially from pituitary damage, impairs metabolic health. The sweet spot is maintaining robust natural secretion through lifestyle rather than injections.

How your body releases growth hormone

GH is secreted in pulses, typically 5-7 per day. The largest burst comes within the first 90 minutes of sleep, during slow-wave (deep) NREM stages. A single night of fragmented sleep can cut GH secretion by more than 50% ^[4]. Exercise triggers the second-strongest stimulus, particularly high-intensity efforts that push above the lactate threshold for at least 10 minutes ^[5].

Fasting is a potent trigger too. A 2025 randomized controlled trial found that 24-hour water-only fasting raised GH levels independently of weight loss, with increases reaching up to 1,225% in individuals with lower baseline levels ^[6]. Extended 5-day fasts nearly doubled pulse frequency from 5.8 to 9.9 pulses per 24 hours ^[7].

Natural ways to optimize growth hormone

Prioritize deep sleep. GH production depends on slow-wave sleep architecture. Consistent sleep-wake times, a cool bedroom (18-19 C), darkness, and avoiding heavy meals or alcohol within 3 hours of bedtime all protect deep sleep duration.

Train at high intensity. Sprint intervals, heavy compound lifts (squats, deadlifts), and circuits that sustain lactate accumulation produce the strongest acute GH response. A 30-second all-out sprint raised GH concentrations more than 450% above resting levels ^[5].

Use fasting windows. Even 16-hour intermittent fasting elevates GH compared to continuous eating. Longer fasts produce larger spikes but aren't necessary for most people.

Manage body composition. Visceral fat suppresses GH secretion. Losing abdominal fat through any combination of diet and exercise restores pulsatile release patterns.

Consider amino acids with caution. Arginine (5-9 g) and GABA (3-5 g) taken before sleep have shown modest GH-boosting effects in small studies, but results are inconsistent and these supplements don't replicate the magnitude of sleep or exercise-driven release.

Exogenous growth hormone: risks and reality

Recombinant human growth hormone (rhGH) is FDA-approved only for diagnosed GH deficiency, not for anti-aging. Using HGH without a prescription is illegal in the United States. Side effects in healthy adults include fluid retention, joint pain, carpal tunnel syndrome, insulin resistance, and a theoretical increase in cancer risk from elevated IGF-1 signaling ^[8].

For people with confirmed pituitary-based GH deficiency, replacement therapy improves body composition, bone density, lipid profiles, and quality of life. A long-term safety review of over 15,800 GH-treated adults found no increased cancer incidence, though cardiovascular monitoring remains important ^[2].

The bottom line: optimizing natural GH production through sleep, exercise, and fasting is both safer and more sustainable than injecting it.