HGH Results: What Studies Measured and When
What published studies measured for HGH, when those outcomes were measured, and what is still unproven.
What studies measured
Each outcome below comes from a published study, with its type and size, strongest design first. Animal and cell results are labelled as such and are not human results.
| Outcome | Result | Study type | Source |
|---|---|---|---|
| Muscle size during retraining | Muscle cross-sectional area increased more with GH than placebo during retraining after immobilization. | Human RCTn = 12 | Journal of applied physiology 2014, PMID 24235105 |
| Tendon structure | GH appeared to stabilize musculotendinous matrix, increasing tendon cross-sectional area and stiffness during rehabilitation. | Human RCTn = 12 | Journal of applied physiology 2014, PMID 24235105 |
| Sleep architecture | Sleep period time and the intensity of slow-wave sleep were lower after rhGH than after placebo in GH-deficient adults (479 vs 431 min; 559 vs 794 uV2). | Human RCTn = 14 | European journal of endocrinology 2013, PMID 23447518 |
| Tendon collagen synthesis | Local rhGH injections increased tendon collagen synthesis in elderly men (an indirect marker of type I collagen synthesis; not a healing outcome). | Human RCTn = 12 | Journal of applied physiology 2012, PMID 22961272 |
| Lean mass and fat | Lean body mass increased with GH alone and with GH plus testosterone versus placebo; total body fat decreased only with the combination. | Human RCTn = 80 | The Journal of clinical endocrinology and metabolism 2006, PMID 16332938 |
| Strength and quality of life | Muscle strength changes were variable; one of six measures increased significantly with GH plus testosterone. | Human RCTn = 80 | The Journal of clinical endocrinology and metabolism 2006, PMID 16332938 |
| Exercise capacity | Four weeks of supraphysiological GH did not improve power output or oxygen uptake. | Human RCTn = 30 | The Journal of clinical endocrinology and metabolism 2005, PMID 15784718 |
| Protein synthesis in older adults | Low-dose GH increased protein synthesis in healthy aged women and men, and testosterone plus GH enhanced this in men (a whole-body protein-turnover measure). | Human RCT | Metabolism: clinical and experimental 2005, PMID 16125527 |
| Night and daytime sleep | GH replacement did not affect night sleep or daytime sleep propensity in GH-deficient adults. | Human RCT | Psychoneuroendocrinology 2005, PMID 15358440 |
| Whole-body protein metabolism | High-dose GH had a net anabolic effect on whole-body protein metabolism in endurance-trained athletes (a leucine-kinetics measure, not muscle size or performance). | Human RCTn = 11 | The Journal of clinical endocrinology and metabolism 2003, PMID 14602753 |
| Insulin-stimulated glucose uptake | Insulin-stimulated glucose uptake fell 52% at 1 week and 39% at 6 months. | Human RCTn = 19 | The Journal of clinical endocrinology and metabolism 2003, PMID 12679422 |
| Lipids | No significant difference in any lipid parameter between GH and placebo at 6 months; HDL-cholesterol fell from baseline. | Human RCTn = 32 | Clinical endocrinology 1998, PMID 10197085 |
| Body composition within 3 months | Within 3 months lean body mass rose 5.09% and body fat fell 10.89%; waist fell 1.42%. | Human RCTn = 148 | Clinical endocrinology 1997, PMID 9404448 |
| Attenuation at 24 months | At 24 months lean body mass was up 3.91% and body fat down 6.42%, smaller than the early effect. | Human RCTn = 148 | Clinical endocrinology 1997, PMID 9404448 |
| Sleep (well-being scale) | The Nottingham Health Profile improved (energy, emotions, sleep), but a similar change also occurred on placebo. | Human RCTn = 148 | Clinical endocrinology 1997, PMID 9404448 |
| Muscle strength | GH did not improve muscle strength over strength training alone in elderly men. | Human RCTn = 18 | The Journal of clinical endocrinology and metabolism 1994, PMID 7525633 |
| Body composition | Lean body mass increased and fat mass decreased in the GH group; body weight did not change. | Human RCTn = 18 | The Journal of clinical endocrinology and metabolism 1994, PMID 7525633 |
| Blood pressure and heart rate | No change in heart rate or blood pressure at rest or peak exercise. | Human RCTn = 36 | European journal of endocrinology 1994, PMID 8180671 |
| Lean mass and leg strength | Lean body mass rose 3.63% vs placebo (in 15 of 23 studies) and leg extension strength 3.17%. | Systematic reviewn = 1157 | JBJS reviews 2026, PMID 41557825 |
| Overall benefit and harm | Limited evidence suggests GH might offer diverse benefits with few adverse effects in older patients with comorbidities. | Systematic review | Growth hormone & IGF research 2024, PMID 38489867 |
| Burn wound healing | Burn wounds in adults treated with rhGH healed 9.07 days faster than with placebo (two trials). | Meta-analysisn = 701 | The Cochrane database of systematic reviews 2012, PMID 23235668 |
| Donor-site healing | Donor-site healing was 3.15 days shorter in rhGH-treated adults. | Meta-analysisn = 701 | The Cochrane database of systematic reviews 2012, PMID 23235668 |
| LDL cholesterol | Total cholesterol fell 4-8% and LDL cholesterol 11-16%; HDL and triglycerides were unchanged. | Systematic reviewn = 534 | European journal of endocrinology 2011, PMID 21339335 |
| Blood pressure and bone density | Blood pressure and bone mineral density were not consistently affected. | Systematic reviewn = 534 | European journal of endocrinology 2011, PMID 21339335 |
| Body composition | Lean body mass rose 2-5% and fat mass fell 7-10% in four studies; two other studies found no change. | Systematic reviewn = 534 | European journal of endocrinology 2011, PMID 21339335 |
| Body composition and lipids | Fat mass changed -0.9 kg, percent body fat -1%, lean body mass +1.8 kg and visceral adipose area -22.8 cm2. | Meta-analysis | The Journal of clinical endocrinology and metabolism 2009, PMID 18940879 |
| Weight | rhGH produced these body-composition changes without inducing weight loss. | Meta-analysis | The Journal of clinical endocrinology and metabolism 2009, PMID 18940879 |
| Lean mass, strength and exercise capacity | Lean body mass rose 2.1 kg (95% CI 1.3 to 2.9 kg), but strength and exercise capacity did not appear to improve. | Systematic review | Annals of internal medicine 2008, PMID 18347346 |
| Conclusion on athletic performance | The review concluded that claims GH enhances physical performance are not supported by the literature. | Systematic review | Annals of internal medicine 2008, PMID 18347346 |
| Quality of life, well-being and health status | In GH-deficient adults, GH replacement improved quality of life (small effect, d = 0.18), well-being (medium, d = 0.47) and health status (small, d = 0.26), based on open studies. | Meta-analysis | Health and quality of life outcomes 2005, PMID 16236167 |
- HGH here means pharmaceutical recombinant human growth hormone (somatropin). The labelled adult indication is growth hormone deficiency (Genotropin, Norditropin, Humatrope); use in healthy adults for bodybuilding, anti-ageing or performance is not an approved indication. The Humatrope label includes a section on abuse and dependence.
- Most RCT evidence is in GH-deficient adults or in older adults; trials in healthy young adults (15784718, 18347346) found a lean-mass increase of 2.1 kg but no improvement in strength or exercise capacity, with more edema and fatigue.
- No study was selected for hair growth, skin, erectile dysfunction, sex drive, thyroid, PCOS, rheumatoid arthritis, arthritis, back pain, joint pain (efficacy), menopause-specific outcomes, men over 40 or women over 40. Searches for skin, hair and sexual function returned only burn, pediatric, Prader-Willi or quality-of-life papers, and no healthy-adult skin trial was found. Joint pain appears only as an adverse effect (arthralgia).
- Tendon evidence (22961272, 24235105) is from 12-person trials in elderly men using collagen-synthesis markers and tissue size; it does not show faster healing of tendon injuries.
- Doses in the studies above vary (GH-deficiency replacement doses vs supraphysiological doses of 0.067 mg/kg/d in athletes); labels state replacement dosing titrated to IGF-1 in GHD adults.
- Long-acting GH products (lonapegsomatropin, somapacitan, somavaratan) were not included, nor pediatric growth-failure trials, which are the main use of somatropin.
Typical timeline
When the studies above measured their outcomes. This is the study schedule, not a promise of when anyone will notice a change.
| When | What was measured | Study type | Source |
|---|---|---|---|
| 3 months | Lean body mass and body fat | Human RCTn = 148 | Clinical endocrinology 1997, PMID 9404448 |
Before-and-after photos
We don't publish before-and-after photos. They can't be verified, rarely show dose, diet or other drugs, and only the most dramatic results get posted.
Common questions
How long does HGH take to work?
The studies we summarise measured outcomes at set points, for example Lean body mass and body fat at 3 months. Timelines outside studies vary.
Do you show HGH before and after photos?
No. Photos can't be verified, rarely show dose, diet or other drugs, and only the most dramatic ones get posted. We summarize measured outcomes instead.
More on HGH
DosageDoses used in published studies, with the source for each.Side effectsWhat labels and studies report, and what is unknown.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.How to injectSites, syringe types and hygiene, step by step.Half-lifeWhat is measured, by route, and what is not.
Sources
- 1Effect of growth hormone on aging connective tissue in muscle and tendon: gene expression, morphology, and function following immobilization and rehabilitation.Journal of applied physiology (Bethesda, Md. : 1985) · 2014PMID 24235105Accessed 2 Oct 2026
- 2Impact of GH replacement therapy on sleep in adult patients with GH deficiency of pituitary origin.European journal of endocrinology · 2013PMID 23447518Accessed 2 Oct 2026
- 3Local administration of growth hormone stimulates tendon collagen synthesis in elderly men.Journal of applied physiology (Bethesda, Md. : 1985) · 2012PMID 22961272Accessed 2 Oct 2026
- 4The effects of growth hormone and/or testosterone in healthy elderly men: a randomized controlled trial.The Journal of clinical endocrinology and metabolism · 2006PMID 16332938Accessed 2 Oct 2026
- 5Short-term administration of supraphysiological recombinant human growth hormone (GH) does not increase maximum endurance exercise capacity in healthy, active young men and women with normal GH-insulin-like growth factor I axes.The Journal of clinical endocrinology and metabolism · 2005PMID 15784718Accessed 2 Oct 2026
- 6Effects of growth hormone and/or sex steroid administration on whole-body protein turnover in healthy aged women and men.Metabolism: clinical and experimental · 2005PMID 16125527Accessed 2 Oct 2026
- 7Night sleep EEG and daytime sleep propensity in adult hypopituitary patients with growth hormone deficiency before and after six months of growth hormone replacement.Psychoneuroendocrinology · 2005PMID 15358440Accessed 2 Oct 2026
- 8High dose growth hormone exerts an anabolic effect at rest and during exercise in endurance-trained athletes.The Journal of clinical endocrinology and metabolism · 2003PMID 14602753Accessed 2 Oct 2026
- 9Growth hormone replacement therapy induces insulin resistance by activating the glucose-fatty acid cycle.The Journal of clinical endocrinology and metabolism · 2003PMID 12679422Accessed 2 Oct 2026
- 10HDL-cholesterol reductions associated with adult growth hormone replacement.Clinical endocrinology · 1998PMID 10197085Accessed 2 Oct 2026
- 11Two years of replacement therapy in adults with growth hormone deficiency.Clinical endocrinology · 1997PMID 9404448Accessed 2 Oct 2026
- 12Effect of recombinant human growth hormone on the muscle strength response to resistance exercise in elderly men.The Journal of clinical endocrinology and metabolism · 1994PMID 7525633Accessed 2 Oct 2026
- 13Cardiovascular effects of growth hormone replacement therapy in hypopituitary adults.European journal of endocrinology · 1994PMID 8180671Accessed 2 Oct 2026
- 14Human Growth Hormone as a Therapeutic Treatment Option in Orthopaedics: A Systematic Review of Dosing, Side Effects, and Clinical Outcomes.JBJS reviews · 2026PMID 41557825Accessed 2 Oct 2026
- 15Growth hormone treatment in aged patients with comorbidities: A systematic review.Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society · 2024PMID 38489867Accessed 2 Oct 2026
- 16Recombinant human growth hormone for treating burns and donor sites.The Cochrane database of systematic reviews · 2012PMID 23235668Accessed 2 Oct 2026
- 17GH replacement therapy in elderly GH-deficient patients: a systematic review.European journal of endocrinology · 2011PMID 21339335Accessed 2 Oct 2026
- 18Effects of recombinant human growth hormone therapy in obesity in adults: a meta analysis.The Journal of clinical endocrinology and metabolism · 2009PMID 18940879Accessed 2 Oct 2026
- 19Systematic review: the effects of growth hormone on athletic performance.Annals of internal medicine · 2008PMID 18347346Accessed 2 Oct 2026
- 20Differential effect sizes of growth hormone replacement on Quality of Life, well-being and health status in growth hormone deficient patients: a meta-analysis.Health and quality of life outcomes · 2005PMID 16236167Accessed 2 Oct 2026
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