by Dr Jess Braid

Dr Jess: The role of growth hormone in adults is largely ignored by the medical community unless we are concerned that the pituitary has been damaged or that it’s producing too much growth hormone. Excess growth hormone due to a tumour is an extremely rare condition called acromegaly or gigantism (if it occurs in teenagers) that causes large hands and feet, changes in your face to have a large jaw, nose and lips and a range of other symptoms. The actor who played Jaws from the Bond movies had this condition. However, research is confirming some great ways to bio-hack this anti-ageing and anti-inflammatory hormone that helps us maintain muscle mass. It also confirms why regular exercise is so important for long term health,  particularly for those over 40.

what is human growth hormone?

Growth hormone (GH) as its name suggests is the hormone that is responsible for our rapid growth as infants and children, when it is at its highest. As adults, it helps our cells grow and repair.  Levels of growth hormone decrease with age so adults have much less GH.

what does growth hormone do?

    • Makes our bones grow when we are growing and stay strong and repair as adults.1
    • Helps regulate our metabolism, blood sugar and electrolyte balance.1
    • Decreases body fat, maintains muscle mass and muscle strength.1 
    • If deficient, supplementing it can increase athletic performance and strength (but supplementing is not beneficial in healthy adults).2
    • Helps us maintain, build and repair our brain, heart, liver, gut and lung cells and cells in other organs, especially after injury or trauma like a heart attack.3 Healthy growth hormone levels help protect our cells and organs from damage and decline.4
    • It helps switch off inflammation and interacts with our immune cells.4
    • It aids wound healing5 and may help slow the ageing process.1
    • For women after menopause, it can reduce belly fat and improve physical performance.

growth hormone pathways

how does growth hormone work?

GH is produced by the pituitary gland in the brain and stimulates the production and release of another hormone, called insulin-like growth factor (IGF-1) from the liver. The role of IGF-1 is to increase cell division, cell growth and cell repair. IGF-1 stimulates the growth of bones, muscle and other tissues. This is how it helps build muscle and trigger the effects above. 

GH release is affected by various hormones, including:1

  • GHRH (growth hormone-releasing hormone) produced by the hypothalamus which triggers its release. 
  • Somatostatin, produced by cells in the pancreas, gut and hypothalamus, reduces the release of growth hormone (and thyroid stimulating hormone). 
  • Ghrelin (the hunger hormone) stimulates the release of growth hormone, which is why fasting is important for raising GH levels.
  • Thyroid hormones work with growth hormones to trigger our growth and development but growth hormone also helps us convert T4 (the inactive form of thyroid hormone) to T3 (the active form). Read more about thyroid hormones here.
  • Leptin is a hormone produced by fat cells which can stimulate the release of GH but is in leptin resistance (which contributes to weight gain – read here) growth hormone is suppressed.  

can you measure growth hormone?

Growth hormone levels are usually only measured in the NHS in children who are not growing properly or in people who have had surgery or trauma to their brain and pituitary gland. Private testing is difficult to obtain but is available from Medichecks at their London laboratory. However, because growth hormone levels fluctuate during the day, a single reading is not always helpful. IGF-1 can also be tested and is much more stable and so more useful as a baseline to measure change if implementing the steps below. Again this is available privately from Medichecks at their London lab. IGF-1 should be within the normal range for your age but higher in the range is beneficial. However,  if it’s too high (usually due to supplementation), it can increase your risk of cancer.

can you take a growth hormone supplement?

Growth hormone levels can be increased with a synthetic supplement but there are significant risks to this treatment,7 unless you have a diagnosed growth hormone deficiency (which can happen after brain surgery or trauma):

  • Carpal tunnel syndrome
  • Increased insulin resistance and risk of diabetes as GH blocks the action of insulin1
  • Swelling, numbness and joint/muscle aches or pains in the arms and legs
  • Joint and muscle pain
  • Enlargement of breast tissue in men
  • Increased risk of certain cancers and so people with a history of cancer or those at high risk shouldn’t take a GH supplement. It can contribute to breast, colon and endometrial cancer tumour progression.1 However this risk does not seem to apply to those with growth hormone deficiency taking a supplement as long as IGF-1 stays within the normal range.8

The use of GH for anti-aging or in sports medicine is controversial and should be carefully considered and monitored. Growth hormone can be increased safely by increasing natural production.1,2 

growth hormone exercise

natural ways to boost growth hormone…

By understanding the factors that deplete growth hormone, we can make changes to optimise it and therefore improve our body composition, strength, inflammation, healing, immune and brain function and slow ageing. 

GH production and secretion decline naturally with age but many lifestyle factors can speed this decline. Growth hormone is lower in those who are overweight or obese and particuarly those who carry belly fat, weight round their middle (belly fat).9 Lack of sleep, poor nutrition a sedentary lifestyle and insulin resistance also reduce levels of growth hormone.10

A number of lifestyle changes can have a dramatic effect on GH levels and the most powerful are deep sleep, calorie restriction (fasting) and exercise. Naturally increasing our body’s production of GH is likely important for ageing well.11


The number one way to naturally increase growth hormone is to exercise. Increased physical fitness and regular training increase GH production in adults and is particularly important to counteract the decline in growth hormone that occurs as we age.12 Exercising regularly to maintain muscle mass becomes even more important when you’re over 40! It also doesn’t matter if exercise hasn’t been a part of your life when you were younger as studies show that even in sedentary older adults, there are improvements in both GH levels and brain function after starting to exercise.13 In fact, exercise can increase GH levels by up to 500%.14

All exercise can quickly improve GH levels but it is likely that HIIT15 (high intensity interval training), aerobic and resistance training16 have the most impact. Endurance exercise (like long distance running) had less significant impact on growth hormone.15 

Making regular exercise a part of your life is important to maintain this improvement. The intensity and duration of exercise and your fitness all influence the GH response.17


Optimising your sleep is another excellent way to raise your levels of growth hormone18 and conversely higher levels of GH improve sleep quality.19 The nighttime increase in human GH is partly dependent on sleep, particularly deep sleep.18 The slow-wave phase of (NREM) sleep in particular has a big impact on the amount of GH we produce. Inadequate sleep, particularly slow-wave sleep, stops the production of growth hormone.20 The more slow-wave sleep you get in a night, the higher the level of GH you produce.20 The impact of GH on ageing and health is another mechanism that shows that if you regularly stay up late and cut down your sleep, you age quicker. 

growth hormone sugar and insulin

reduce sugar

We regularly talks about sugar and its negative impact on health but here is yet another reason to reduce your sugar (and refined carb) intake and work on your blood sugar (and insulin) levels. When our diet is high in sugar (including fruit sugar) or refined carbohydrates (mostly white flour), we have high insulin levels. Insulin inhibits GH levels even in healthy people.21 The higher our insulin levels, the less growth hormone we will produce.21 Low GH levels are another driving factor in inflammation for those with insulin resistance, which is associated with obesity and weight gain.22



Intermittent fasting (fasting for short periods) can significantly increase growth hormone levels. In a trial of over 200 people, fasting for 24 hours increased GH 1,300 percent in women and nearly 2,000 percent in men.23 Improvements in IGF-1 (responsible for the effects of GH) have also been measured in trials of a 16/8 fasting schedule24 which we suggest as a simple and easy way to get the benefits of fasting.

reduce alcohol

Alcohol can cause a decrease in growth hormone that lasts for a period of time after consumption.25 Alcohol also disturbs slow wave sleep and can disrupt blood sugar levels and so impacts the other main factors that can cause low GH levels.

natural supports

Ensuring you have good Vitamin D levels and supplementing if necessary has been shown to increase circulating IGF-126 (responsible for the positive effects of growth hormone). You can read more here about vitamin D here and check your levels with a simple test from your doctor.

The traditional Chinese herb astragalus has been shown in animal studies to stimulate the production of growth hormone.27 Astragalus is a very safe and commonly used Chinese herb often added to soups and stews and consumed as a food. Read more about astragalus here. 

Melatonin is found naturally in tart cherries, raspberries, goji berries, almonds and walnuts. It is also a hormone produced by our pineal gland that helps trigger sleep, in response to decreased light levels. Melatonin is shown to increase secretion of growth hormone and it can help sleep quality and deep sleep. 0.5-50mg of melatonin before sleep has been shown to markedly increase growth hormone and improve sleep quality.28,29,30 Our favourite supplement for sleep is Cytonight by Cytoplan which contains natural melatonin in tart cherry extract.

L-glutamine supplements may help growth hormone. A small study showed 2g of glutamine raised levels of circulating GH in 90 minutes.31 A later small study of older adults taking glutamine, glycine and niacin (vitamin B3) daily for 3 weeks increased growth hormone levels by up to 70%.32  Glutamine is an amino acid found in meat, especially chicken, fish, cabbage and beans and is in bone broth, one of our favourite superfoods. L-glutamine powder (available from Cytoplan) is an excellent post-workout choice that can enhance muscle recovery.33


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