As its name suggests, human growth hormone (HGH) — also known as growth hormone (GH) — is a natural compound that stimulates tissue and bone growth in humans. Along with growth, this powerful hormone also regulates metabolic, cognitive, and adrenal function, among other things.
Human growth hormone is best known for stimulating growth in adolescence, and as a performance-enhancing supplement in adults. Some even claim that HGH treatment has anti-aging effects.
What is Human Growth Hormone?
Human growth hormone goes by many names. HGH, GH, somatotropin — they all refer to the same chemical messenger produced in the pituitary gland — a gland about the size of a pea behind the bridge of your nose[*].
Growth hormone was originally discovered as a growth promoter in infants and adolescents, but researchers now know its influence on protein production, fat utilization, blood sugar and insulin levels, and more.
HGH levels start to decline around age 30, decreasing by a factor of two or three during the fourth decade of life, and continuing to decline with age[*].
Your pituitary gland releases HGH in small bursts, usually after exercise or during deep sleep. This makes it a little more difficult to measure HGH in the blood, because levels fluctuate throughout the day.
And like all hormones, growth hormone doesn’t work alone. HGH secretion is regulated by several other compounds.
What Stimulates Growth Hormone Secretion?
Of the many chemicals that regulate HGH levels, here are the main players[*]:
Ghrelin is your main hunger hormone, produced mainly in the stomach, with small amounts produced in your small intestine, pancreas, and brain[*]. Ghrelin rises in response to low blood sugar, stimulating your appetite so you know when your body needs more food for energy.
Rising ghrelin signals the release of growth hormone, which causes your liver to release glucose into your blood. This functions to restore blood sugar levels and prevent hypoglycemia[*].
#2 Growth Hormone Releasing Hormone
You probably can guess the job of growth hormone releasing hormone, or GHRH. Made in your hypothalamus, GHRH stimulates HGH secretion and distribution[*].
Somatostatin — a chemical produced by most cells and tissues — does the opposite of ghrelin and GHRH. It inhibits HGH production[*].
How Does HGH Work?
After you produce HGH naturally through your pituitary gland, it stimulates your liver and other tissues to make a protein called insulin-like growth factor-1 or IGF-1.
IGF-1 then stimulates bone, muscle, and tissue growth throughout your body.
That means, more HGH means more IGF-1.
But going from HGH to IGF-1 isn’t an A to B process[*]. More like A to D:
- Your pituitary gland releases HGH
- HGH binds to receptors in liver cells (hepatocytes), activating molecules called janus activating tyrosine kinases (JAKs)
- JAKs bind to transcription factors called STATs and carry them into the cell’s nucleus
- Your nuclear genes tell the cell to start producing IGF-1
Primary Functions of Growth Hormone
#1 HGH Stimulates Growth
There are two ways that HGH promotes growth.
The first is the direct pathway.
HGH binds to chondrocytes and osteoblasts — cells that promote, bone and cartilage growth[*]. This action, as you might imagine, is crucial for growing children.
The biochemistry behind cellular growth is complex, but simply put: HGH tells proteins to swim to the cell’s nucleus, these proteins nudge your genes, and your genes tell your body to grow more bone and cartilage.
The second HGH growth-promoting pathway is more indirect.
Remember IGF-1? Some scientists argue that HGH is merely a precursor to this more powerful growth factor[*]. IGF-1, they say, is the key hormone for growth, repair, healing, cellular replication, and so much more.
There may be truth to this theory[*]. IGF-1:
- Boosts metabolism
- Promotes anabolism (muscle growth and tissue building)
- Increases cellular division and replication
- Prevents apoptosis (cell death)
So you definitely want some IGF-1 for growth and repair, though excess amounts may accelerate aging and cancer progression. More on that later.
#2 HGH Influences Metabolism
Growth hormone also impacts your metabolism indirectly by boosting IGF-1.
IGF-1 is an anabolic hormone, aka a building hormone.
When IGF-1 is around, your cells[*]:
- Use more amino acids, the building blocks of protein
- Build more muscle mass via protein synthesis
- Increase lipolysis, the splitting apart of triglycerides (stored fat cells)
- Increase beta-oxidation of adipocytes (read: burn more fat)
HGH affects glucose (blood sugar) metabolism as well.
You release more HGH when blood sugar is low. Growth hormone then binds to your liver, causing an uptick in gluconeogenesis — a process by which your liver creates glucose from protein.
Benefits of Human Growth Hormone
Benefits of more HGH include stronger bones and cartilage, more muscle mass, and better performance and energy levels.
But that doesn’t mean you should start supplemental growth hormone. Though some people benefit from synthetic HGH, most researchers advise caution and up to 30% of users report uncomfortable — and sometimes dangerous — side effects[*].
Instead, these are practical reasons to boost HGH naturally. And it’s easier than it sounds.
Benefit #1: Muscle Growth And Retention
HGH is known for boosting muscle growth and preventing age-related muscle decline.
This works in a couple of ways:
- As you age, you’re more likely to lose muscle due to an increase in a muscle-shrinking hormone called myostatin. Growth hormone inhibits myostatin (mostly through IGF-1 and another pro-growth pathway called mTor)[*].
- HGH also promotes muscle growth by helping amino acids get into your muscle tissue, which stimulates protein synthesis.
So, can you just inject growth hormone and get huge?
That’s not clear. One study showed that — in men over 50 without specific HGH deficiency — supplemental HGH did not affect bench press strength over placebo. Growth hormone therapy did, however, boost lower body strength[*].
For muscle growth, the safest thing to do is foster natural HGH. More on that later.
Benefit #2: Bone Density
As you learned earlier, HGH stimulates osteoblasts — specialized cells that create new bone mass. Most of this bone growth occurs early in life.
But even later in life, you need osteoblasts to maintain bone density and heal broken bones. Growth hormone is central to this process.
The research supports this. In 32 adults with growth hormone deficiency (GHD), GH therapy increased both bone density and bone turnover[*].
Benefit #3: Decreased Body Fat
Those deficient in growth hormone tend to have more fat mass. This fat presents as both visceral fat (around the organs) and adipose tissue (body fat). GH therapy helps reverse this problem.
HGH reduces body fat by activating lipase, your fat-digesting enzyme[*].
Lipase is responsible for initiating a process called lipolysis. Lipolysis is the breaking apart of stored fat (triglyceride) into usable fat, or free fatty acids.
Some describe lipolysis as the destruction of fat cells. This is somewhat misleading. It’s more accurate to say lipolysis is the shrinking of fat cells.
With age, lipolysis tends to decrease, and fat storage increases. Researchers speculate that HGH decline may be to blame.
Benefit #4: Anti-Aging Potential?
The relationship of growth hormone to aging is complex. There’s a tradeoff. You don’t want too little, and do you want too much[*].
If your HGH is low, your IGF-1 will also be low, which promotes the aging process.
In a low IGF-1 state:
Also, although centenarians (people over 100) have lower IGF-1 than the general population, the centenarians with the lowest levels also have increased dementia risk[*].
Bottom line? To age better, you need some HGH, but be wary of excess unless you’re obviously deficient.
Benefit #5: Brain Function
Your central nervous system can synthesize HGH and IGF-1, and both are critical for early brain development[*].
Growth hormone also may trigger new brain cell growth (neurogenesis) after brain injury or age-related cognitive decline[*]. For example: after administering GH to older mice, researchers noticed new neurons in both the cortical and hippocampal regions of their brains.
Such promising results on humans are yet to come, but it’s well-documented that older adults with GH deficiency can be helped — both emotionally and cognitively — by supplemental growth hormone[*].
The likely mechanism? Neurotransmitters.
HGH affects them all: serotonin, dopamine, norepinephrine, glutamate, choline, opioid receptors, and more. Growth hormone also stimulates brain-derived-neurotrophic-factor (BDNF), a brain chemical implicated in memory.
Benefit #6: Liver Repair
The human liver contains many growth hormone receptors. Unsurprisingly, those with growth hormone deficiency tend to suffer from liver dysfunction[*].
When the liver gets injured, HGH comes to the rescue. It repairs the damage.
The liver, by the way, has an incredible ability to regenerate. You can cut someone’s liver in half, and — provided that person is healthy — the liver will fully regrow[*]. With the help of GH, of course.
Benefit #7: Cardiovascular Health
In the growing fetus, growth hormone functions as a myocardial (heart muscle) growth signal. HGH also increases the force of contraction, increasing fetal blood flow, which means more nutrients and oxygen delivery to cells[*].
In adults too, growth hormone has many cardiac-related roles. For one, HGH helps coat the heart with necessary collagen.
HGH also augments blood vessel health. This happens via several mechanisms:
- GH fosters nitric oxide (NO) production, which relaxes blood vessel walls and lowers blood pressure
- GH triggers blood flow to the muscles
- GH prompts angiogenesis, or the creation of new blood vessels
All things considered, it’s clear that healthy levels of HGH are imperative for a healthy heart.
Who Needs More Growth Hormone?
Age 30 is when growth hormone starts declining. Because of this, you could argue that those 30 and up should be optimizing HGH naturally.
Without enough HGH, bone density, muscle growth, body composition, wound healing, and metabolism suffer.
Sometimes natural methods aren’t enough, and those with growth hormone deficiency often need synthetic HGH injections.
This doesn’t mean everyone should inject growth hormone supplements — that can come with some nasty side effects. As always: consult your medical professional.
Luckily, most healthy people won’t need to consider synthetics. But for those that do…
HGH for Growth Hormone Deficiency
Growth hormone deficiency (GHD) occurs in both young and old, causing a wide range of health problems.
Sometimes, GHD has an obvious genetic cause. Most of the time, however, the cause of GHD is unknown, though deficiency is correlated with aging[*].
Children with GHD often present with dwarfism due to inadequate bone growth. In adults, the symptoms of GHD are less obvious and include:
- Increased fat mass
- Low bone density (osteoporosis)
- Muscle wasting
- Insulin resistance
- Pituitary adenoma
In these cases, if natural efforts to boost HGH fail, treatment with synthetic GH can help.
HGH For Athletes?
If you live an active life, you’re constantly stressing muscle growth and bone maintenance. Growth hormone can help with both.
But there’s no evidence that supplemental GH helps with athletic performance. In fact, it may hinder it.
In a 2008 review published in the Annals of Internal Medicine, researchers analyzed 44 articles (303 participants) on the exercise-related effects of HGH supplementation[*].
They found that:
“Although the limited available evidence suggests that growth hormone increases lean body mass, it may not improve strength; in addition, it may worsen exercise capacity and increase adverse events.”
How To Test For HGH
Growth hormone levels are in constant flux. Because of this, standard blood tests for HGH are unreliable[*].
Enter the HGH stimulation test. You fast overnight, and in the morning you’re given one of the following substances (called a pharmacological challenge):
- Insulin (to induce hypoglycemia)
How to Get More Human Growth Hormone
You can boost HGH naturally or synthetically. Natural ways include sleep, adequate protein intake, and exercise.
If your condition warrants it, you can also receive synthetic growth hormone injections.
GH therapy is approved for a small number of conditions, including[*]:
- Growth hormone deficiency
- Short bowel syndrome
- Kidney disease
- Muscle wasting from HIV or AIDS
- Turner’s syndrome and Prader-Willi syndrome, both genetic disorders affecting childhood development
Many people — athletes, mainly — also inject growth hormone for off-label, muscle-building purposes. But as you learned, there’s little wisdom or evidence behind this practice.
Must synthetic HGH be injected? Yes.
Despite the claims of many marketers, injections are the only proven (and FDA approved) way to take synthetic growth hormone. There’s simply no evidence for the efficacy of HGH pills, sprays, or powders.
Side Effects and Risks of Synthetic HGH
GH therapy has the following well-documented side effects[*]:
- Carpal tunnel syndrome
- Joint pain
- Edema (swelling of various body parts)
- Insulin resistance
Thanks, in part, to these side effects: injecting HGH for anti-aging purposes is a bad idea. It’s also a bad idea because excess GH may accelerate the aging process.
Recall: excess IGF-1 (provoked by excess HGH) can help proliferate cancer cell growth.
But low HGH is just as bad, causing weak muscles, brittle bones, and cognitive decline.
7 Ways to Increase HGH Naturally
Supporting growth hormone doesn’t require expensive drugs or therapies. In fact, most of the recommendations below are normal parts of a healthy lifestyle.
#1 Sleep Well
HGH spreads in pulses, with the largest occurring in slow wave, delta sleep. Deep sleep.
The relationship is simple. Sleep deprivation diminishes HGH production.
Since growth hormone declines with age, adequate deep sleep is a non-negotiable for older adults, with GH beginning to decrease two- to threefold between age 30-40[*]. No matter your age, however, GH production suffers when you don’t sleep enough.
To improve sleep, try these tips:
- Sleep in a cool, dark room
- Avoid blue light at night to avoid suppression of melatonin, your sleep hormone
- Expose yourself to bright light early to optimize circadian rhythm
- Don’t check email at night
- Eat a high protein breakfast, shown to improve salivary melatonin levels[*]
- Take 400-600 milligrams of magnesium before bed for a calming effect[*]
Bottom line: If you’re getting at least 7-8 hours of restful sleep per night, you’re doing well by HGH.
#2 Eat Enough Protein
To build muscle, you must eat protein. When you digest that protein, it splits into amino acids. These building blocks are then used to form every tissue in your body.
Amino acids also send a cellular signal that it’s time for your muscles, tissues, collagen, and organs to growth and repair.
Dietary protein is pivotal for growth — yes, even as you age. And low-protein diets can lead to muscle wasting, osteoporosis, and a host of other issues[*].
- Pumpkin seeds
Bottom line: To get all your amino acids (including arginine), eat around 30% of your calories from complete protein sources like meat, whey, and eggs.
#3 Exercise At High Intensity
Growth hormone injections may not boost exercise performance, but exercise (of all types) does boost growth hormone.
Of all exercise, high-intensity exercise — sprints, Crossfit, no-rest gym circuits — has the most significant effect on HGH. That’s because hard exercise boosts lactic acid concentrations in the muscle, yet another growth-hormone-releasing signal.
In one study, men who lifted weights (without rest) had significant spikes in HGH following the workout[*]. The rested group saw a rise too, though not as pronounced.
Another group of researchers found the size of HGH pulses to be directly correlated with exercise intensity[*]. The harder the exercise, the bigger the pulse.
Note: these HGH boosts were temporary. Probably a good thing. You don’t want excess growth hormone hanging around for too long. Only when you need to build.
Bottom line: Add more high-intensity efforts into your routine once or twice per week for an extra surge of growth hormone.
#4 Have A Sauna
Sitting in a hot sauna — a form of hyperthermic conditioning — causes a massive, sustained release of growth hormone.
The amount of growth hormone you release depends on the time and temperature of the sauna sitting. The hotter and longer the session, the more growth hormone liberated.
Here are the relevant results:
- Two 20-minute sessions at 80° C (176° F) doubled growth hormone[*]
- Two 15-minute sessions at 100° C (212° F) quintupled (x5) growth hormone[*]
- Two hour-long sessions per day for three days (80° C) caused a 16-fold increase in GH[*]
A word of caution: to prevent heat stroke and dehydration, be careful not to overdo the sauna. Listen to your body — more is not always better.
Bottom line: 15-20 minutes in the sauna a few times a week can boost GH anywhere from two to five times.
#5 Try Natural Supplements
A variety of supplements have been shown to increase HGH levels. These include:
- Alpha GPC: 1 gram of this brain-boosting nootropic temporarily increased GH levels by 290% in healthy young men[*]
- Melatonin: Taking this sleep-promoting hormone has been shown to moderately increase growth hormone secretion[*]. Anywhere from 100 micrograms to 10 milligrams is safe.
- GABA: GABA is a neurotransmitter — a chemical messenger in your brain. Taking a GABA supplement can significantly (though transiently) raise GH levels[*].
- Creatine: 20 grams of this natural exercise-enhancer elevated GH for several hours in healthy men[*]
- Glycine: Glycine is the most abundant amino acid in collagen. Supplementation has been shown to raise HGH in healthy individuals[*].
- Arginine: The amino acid arginine helps deploy HGH during sleep[*]
Precautionary note: taking a “stack” of supplements to elevate HGH may have unintended side effects. Favor other, more holistic methods for HGH production, like optimizing deep sleep and exercise.
Bottom line: Test one or two natural supplements at a time for an increase in muscle growth, bone density, and recovery.
#6 Fast Intermittently
Two days of fasting has been shown to increase growth hormone levels by a factor of five[*].
Hold on. Two days without food? If you’re cringing, you’re not alone.
Fortunately, intermittent fasting — not eating for 12-24 hours on a daily or semi-daily basis — carries most of the same benefits.
The main benefit is metabolic. Fasting keeps your blood sugar and insulin levels low. Instead of burning glucose, you start burning fat.
Keeping insulin low has another benefit: it prompts HGH release. High insulin, on the other hand, suggests high blood sugar, which inhibits growth hormone.
Fasting may also boost HGH by[*]:
- Stimulating growth hormone releasing factor
- Blunting the power of somatostatin — an HGH inhibitor
Bottom line: Fasting or intermittent fasting (IF) can increase HGH. For more about IF, read this.
#7 Go Keto
The ketogenic diet is a high-fat, low-carb diet that puts you in a unique metabolic state called ketosis. In ketosis: you burn less glucose, burn more fat, and produce ketones. The result of these changes is stable energy, clear cognition, and fewer cravings.
Just like fasting, keto keeps blood sugar and insulin levels, low, which boosts HGH[*].
Wait, keto is low-carb. Don’t you need carbs to build muscle?
Not at all. In fact, a ketogenic diet improves muscle growth more than a high-carb Western diet[*]. More lean mass, less fat.
Bottom line: Although there’s not exact data, it’s highly likely that keto raises HGH levels more than higher-carb diets.
Optimize Your HGH
After age 30, growth hormone starts to decline.
Luckily, you can mitigate the effects of this decline — weak muscles, brittle bones, slower cognition, etc. — without hormone injections. Considering the side effects of synthetic growth hormone, this is good news.
It’s fairly simple. If you sleep well, eat enough protein, exercise regularly, hit the sauna, and keep insulin low via fasting or ketosis — you’ll be on your way to optimal HGH.
Best of all, the natural practices suggested here don’t only stimulate HGH, they also benefit your overall health.