Which hormones affect muscle growth in men?

We often take our hormones for granted and don’t think about them until something isn’t quite right. But we should give them more praise. A healthy hormone system enables us to stay in shape and conduct our daily activities. And that system is essential for people trying to gain muscle. 

It can be frustrating to dedicate time and effort to your physique and not see the desired results. You might have tried changing your diet or your training plan. But your hormones could be responsible for your lack of muscle growth.

This guide looks at the main muscle building hormones, including testosterone, cortisol, and growth hormones. It also explains when hormone imbalances may be affecting progress, and when blood testing may be worth considering.

• Which hormones affect muscle growth?
• Testosterone and muscle growth
• How does cortisol affect muscle growth?
• How does growth hormone affect muscle growth?
• How does insulin affect muscle growth?
• How can insulin-like growth factors affect muscle growth?
• Why you might not be building muscle
• How to ensure your hormones aren’t affecting your muscle gain
• Top tips to enhance hormone production
• When a hormone blood test may help
• Which blood test might help?

Which hormones affect muscle growth?

Hormones are vital in regulating your metabolism (the internal process that governs our energy and processes our food intake).

During and after a workout, the body is flooded with different hormones. These are either anabolic (hormones that use energy) or catabolic (hormones that release energy). Only the muscles stimulated during this exercise are subject to the effects of these hormones [1].

For muscle growth, you need more anabolic hormones than catabolic hormones. 

Anabolic hormones for muscle growth include: 

• Testosterone 
• Growth hormone (GH) 
• Insulin 
• Insulin-like growth factors (IGFs) 

Anabolic hormones enable muscle growth through a process known as anabolism (in which energy is used to build molecules from smaller units).

Catabolic hormones (such as cortisol) do the opposite, inhibiting muscle growth through processes, breaking down molecules to release energy (as when digesting food).

If there is a higher level of catabolic hormones than anabolic hormones in the body, you will begin to lose muscle mass. Therefore, hormonal disruptions (like a thyroid disorder) can affect these processes, your overall metabolism, and muscle gain [2].

If you’re concerned about a hormone imbalance or want to determine your baseline levels, a blood test such as our Ultimate Performance Blood Test can provide insight.

Both anabolic and catabolic hormones are important to consider in the process of building muscle, but which ones are key, and how do you make sure you have the right levels.                  

                  

 

Testosterone and muscle growth
 

Testosterone is primarily produced by the testicles (and the ovaries in women). Testosterone regulates muscle mass, strength, fat distribution, libido, and bone mass [3], making it one of the most important hormones for bodybuilding.   

Bodybuilders sometimes use testosterone supplements to enhance their physique and muscle-building capability. However, using anabolic steroids like testosterone has been banned in sports competitions as it may give an unfair advantage and potentially cause long-term adverse health effects.  

Natural techniques that you can use in the gym to help boost your testosterone levels include:  

• Keeping workouts shorter than 60 minutes  
• Doing multiple sets of each exercise   
• Including compound exercises (exercises that use more than one muscle group, such as squats)   
• Working out your legs - stimulates your largest muscles and therefore produces more testosterone [1]  

How does cortisol affect muscle growth?
 

Cortisol is the main catabolic hormone that can affect muscle growth. Cortisol is triggered by physical and emotional stress. It can start to break down your muscles when your blood sugar is low (people who enjoy endurance sports may have experienced its effects). 

But how can you minimise cortisol when training?

The answer is simple - try to avoid lengthy cardio sessions. 

Exercises that cause growth hormone (see below) to be released, such as using heavy weights and large muscle groups, also stimulate high cortisol levels. But when training is completed in short-term intervals, cortisol can be helpful, as muscles need to break down slightly to grow.

Find a good balance to avoid overtraining. 

How does growth hormone affect muscle growth?
 

Growth hormone (GH) helps to: 

• Build skeletal muscle tissue 
• Develop body strength 
• Eliminate body fat 

GH production declines with age, and the less GH you produce, the more body fat you accumulate [4], which is why it may be harder to lose weight as you age.

Your body releases GH during REM sleep and uses this time to repair damaged muscle cells. Therefore, improving your sleep quality may, in turn, help your workout efforts.

Exercise, in particular, compound movements that use multiple joints, such as squats or bench presses, also release GH. The more muscle fibres you use, the more GH your body will create.

Try to shorten your workouts (approximately 30-40 minutes), as the quicker, more intense duration produces a higher hormone output. 

How does insulin affect muscle growth?
 

Insulin is responsible for storing food breakdown in the muscles and liver. As another anabolic hormone, it moves amino acids into your muscle cells to help repair tissue.

Insulin can have positive impacts on your muscles but could also become a burden if you have excess body fat. The production of insulin is heavily influenced by diet and exercise, so it is something you can control. However, training can increase your body’s sensitivity to insulin, which is why it’s always so hard to lose the last bit of fat.

Once you’ve lost some weight, your body shifts into survival mode, trying to protect the remaining fat and muscle it needs to function. To combat this, try eating healthy fats that insulin is less sensitive to. 

Healthy fats include: 

• Fish 
• Nuts 
• Coconut oil 
• Avocados 

How can insulin-like growth factors affect muscle growth?
 

Insulin-like growth factors (IGFs) are produced in the liver in response to the growth hormones - if GH levels rise, so do IGFs.

As the name suggests, IGFs stimulate muscle growth. They increase lean body mass, helping you burn fat, improve your physical endurance, and accelerate your recovery time [5].

Your IGF levels peak during puberty and gradually decrease with age. Exercise is the best natural way to increase your IGF levels. We recommend either High-Intensity Interval Training (HIIT) or resistance training. Improving your sleep quality and avoiding alcohol can also benefit your IGF levels.

Why you might not be building muscle
 

If muscle gain has slowed down, hormones may be part of the picture, but they are rarely the only explanation. More often, progress stalls due to a mix of factors, such as insufficient recovery, insufficient protein, inconsistent training, poor sleep, or stress. Hormones become more worth looking at when poor progress is accompanied by other signs such as low energy, low libido, poor recovery, or noticeable changes in body composition. 

How to ensure your hormones aren’t affecting your muscle gain
 

You should try to minimise your catabolic hormone release by keeping your workouts short and ensuring you are not excessively stressing your muscles.

Aim to stimulate your anabolic hormones for muscle growth through weight training and HIIT cardio workouts.

Ensure you are also fuelling your body right. Certain foods can affect your hormones. 

Top diet tips for your hormones include:

• Eating fewer carbs can increase your growth hormone. 
• Eating carbs before or during your workout can minimise cortisol levels 
• Fasting – when done safely, this can increase GH levels 
• Eating protein after a workout can keep your testosterone levels high 
• Sipping a sports drink throughout your workout helps to keep your glucose levels up 

Aside from diet and training movements, other less obvious factors could influence your hormone production and progress. So, we’ve put together some extra top tips to keep your hormones balanced when training. 

Top tips to enhance hormone production
 

1. Perform aerobic and anaerobic exercises on separate days, as they each have distinct effects on the body; doing them in close succession is counterintuitive and can lead to inflammation or elevated cortisol levels. 
2. Try to get good-quality sleep, as not only would you feel well-rested and ready to tackle any workout, but your GH levels are stimulated during deep sleep. 
3. Do weight training in the evenings rather than early morning for the best gains. Your cortisol levels tend to be at their highest soon after you have woken up. 

Other factors could affect your hormone production, such as health conditions. If you are struggling to gain muscle, a health check, such as our Ultimate Performance Blood Test or our Male Hormone Blood Test, could help you identify any underlying conditions that may be affecting your progress.

We also have more information on sports performance, from diet to supplements, in our sports performance guide. 

When a hormone blood test may help
 

If your progress at the gym has stalled and is accompanied by symptoms such as fatigue, poor recovery, low sex drive, or changes in body composition, a blood test may provide a clearer picture. Testing can be useful when you want to look beyond training and nutrition and see whether hormones or recovery markers could be affecting performance.

Depending on your symptoms and goals, blood testing may help you assess levels of testosterone, cortisol, and other markers associated with recovery, stress, and overall health.

Which blood test might help?
 

If testosterone is your main concern, a focused testosterone test may be enough. If the picture feels broader, for example, if progress has stalled alongside fatigue, poor recovery, or wider health concerns, a more complete hormone or performance panel may be a better place to start. 

Hormones do affect muscle growth, but they are only one piece of the puzzle. Training, nutrition, sleep, and recovery still matter most. That said, if you are struggling with muscle gain alongside fatigue, low libido, poor recovery, or changes in body composition, it may be worth looking more closely at your hormone health.

 

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References

1. Speck, C. (2019) Master Your Hormones to Maximise Muscle Growth. [online] Fit Plan. [Accessed 28 April 2026]. 
2. Marcin, A. (2019) Catabolism vs Anabolism: What's the Difference? [online] Healthline. [Accessed 28 April 2026]. 
3. Wein, H. (2013) Understanding How Testosterone Affects Men. [online] National Institutes of Health. [Accessed 28 April 2026]. 
4. Rogers, P. (2020) How to Stimulate Hormones for Bodybuilding. [online] Very Well Fit. [Accessed: 28 April 2026]. 
5. Eriksson, A. (2020) Growth And Longevity: The Enigma And Potential Of IGF-1. [online] Breaking Muscle. [Accessed 28 April 2026].