Hormones – Natural Mechanism of Muscle Growth

When pumping iron in the gym, we think about growing bigger muscles, gaining strength and flexibility. But it is seldom that people wonder about the body’s natural mechanism of muscle growth and how that process actually works. This brings us to a discussion about hormones.
Hormones, produced by endocrine glands, are biochemicals that are transported via circulatory system to target organs. They coordinate our cell behavior and physiology. The release of hormones (which can be anabolic and catabolic) can stimulate muscle growth or decrease, as well as fat-storing or fat-burning processes. We can say that hormones are what defines us. They guide us, the choices we make, our reflex reactions in high-risk situations, our appetite and sexual attraction.
In the human body, hormones that affect muscle growth are: insulin, IGF-1, glucagon, growth hormone, testosterone, cortisol, thyroid hormone and estrogen. Muscle gain and definition are conditioned mostly by testosterone and growth hormone (GH). IGF-1, glucagon and insulin control blood sugar levels, and can trigger both muscle growth and fat storage. Insulin and thyroid hormone are supportive to testosterone and GH, while estrogen and cortisol function as catabolic (catabolism is a process of muscle protein breakdown).


Testosterone, also known as “male hormone”, is the hormone which affects strength and muscle size the most. Women also produce it, but up to 8 times less than men. It directly influences the process of protein synthesis and needs to be kept at the highest level possible in order to produce a constant effect. According to WebMD, the normal testosterone range is between 300 and 800 ng/dL (nanograms per deciliter). Testosterone levels can be controlled with a proper diet which includes lots of zinc, fat (for cholesterol, which affects testosterone synthesis), and vitamins B and C.
Boosting the production of testosterone can also be achieved through intense resistance training with short rest intervals. Alcohol consumption is known to lead to a decrease in testosterone levels. Rest more between workouts, elevate our carb intake periodically, avoid alcohol, eat regularly and supply your body with necessary fats. For more way to boost your testosterone naturally check out this article.
Some helpful supplements are Tongkat Ali Extract and Testofuel.


It is our body’s way of controlling blood sugar levels (glucose). Insulin, along with glucagon and other hormones, keeps the glucose level in check, and carries amino acids needed for protein synthesis. Produced in the pancreas, insulin can promote both muscle build and storing fat (due to excessive amounts of insulin at the wrong times), so it must be used strategically. With an appropriate diet, you can control insulin levels in your body.
Carbs cause the largest insulin release (almost all consumed carbs get converted into glucose), proteins induce a smaller release, while fats don’t affect blood sugar increase almost at all. Choose the time of day for nutrition intake. Glucose is stored in muscles and liver, and their storage is at the lowest point in the morning and after workout. Thus, these are parts of day when you should take advantage of the anabolic effects of high insulin.

Growth Hormone

Growth hormone (GH) has a function similar to insulin’s. It stimulates cell reproduction, growth and secreting IGF-1 hormone (Insulin-like Growth Factor). If you’re trying to lose weight, you will probably change your diet and exercise more. Our bodies tend to lose both muscles and fat, but it is essential to maintain the muscle mass. Muscles are maintained better by keeping a high level of GH. The production of this hormone can be promoted with regular =sleep (7-8 hours), heavy weight training (for which you can consult with a professional fitness trainer), cardio and avoiding excessive insulin release.

Glucagon & IGF-1

While insulin keeps the blood sugar levels down, glucagon boosts them when too low. When blood sugar level is low, body starts the process of muscle breakdown (where glucose is released through breakdown of glucagon) and stored fat for extra energy. In case of hunger (up to 5 hours without food intake), glucagon starts promoting muscle breakdown for fuel. Higher glucagon levels are significant because they lead to burning stored fat during fat loss diets.
IGF-1 (Insulin-like Growth Factor 1) is essential for childhood growth and muscle gain in adults. It can affect every type of cell, but the cells most positively affected by IGF-1 are ones in muscle, lungs, kidney, bone, nerves, skin tissue and liver. It is a chain of different amino acids, released into the bloodstream when insulin and GH levels are simultaneously high. GH levels are high immediately after workout, so eating a meal rich in protein or carbohydrates will send insulin levels up. That will result in releasing IGF-1.


Also known as “stress hormone”. Cortisol burns body fat, but besides that it has mostly negative effects. It weakens the immune system by shrinking the thymus gland, promotes heart diseases, and causes depression, insomnia and fatigue. Minimize stress and caffeine intake, eat simple-sugar rich nutrients 2-3 times per week, and take zinc, calcium and magnesium to “reduce” the stress.

Thyroid Hormone & Estrogen

Low thyroid hormone levels lead to a reduction in calorie burning, protein synthesis and slowing down of the metabolism. To keep the levels high, eat foods rich in iodine and every 10 days consume more carbs than usual, so to prevent your body to getting used to low-calorie dieting. That will cause the thyroid gland to up-regulate and boost your metabolic rate.
Produced to a lesser degree in men, and mostly in women, estrogen negates the fat loss and bodybuilding aims. One should avoid elevated estrogen levels, and lower them by decreasing body fat (testosterone is turned into estrogen with help from aromatase, an enzyme produced from fat tissue), and a vegetable rich diet which includes cabbage, broccoli and cauliflower.
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Closing Word

And there you have it; hormones that play a role in muscle growth and what you can do to affect their levels (secretion) in order to promote healthy muscle growth. Notice that the emphasis is on the word healthy.

Mathews McGarry

Mathews McGarry

Mathews McGarry is passionate about many forms of strength training, and spent years lifting, dragging and flipping all manner of heavy objects. After graduating on the Faculty of Health Sciences, he started writing about his experiences, and sharing advices for better life. Follow him on Twitter.

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