Testosterone, Growth Hormone, IGF-1 and Insulin

February 25, 2019
13 min read

Testosterone Growth Hormone IGF-1 and Insulin

Nutrition and Workout Strategies

Several hormones play a critical role in exercise in general and strength training in particular. Testosterone, growth hormone and insulin-like growth factor (IGF-1) provide strength and muscle growth stimulus; cortisol, epinephrine and norepinephrine and glucagon control access to fat and glucose fuels by manipulating the release of stored fuel when needed in addition to other important functions; and insulin provides the storage impetus for the fuels derived from the food we eat. Getting these hormones to work so that you can maximize muscle and strength is one of the secrets of natural weight training. In this article I’ll concentrate on how you can get the most from the muscle building hormones we all share.


Testosterone is for the most part a male hormone produced by the testicles, although a smaller amount is produced by the adrenal glands. This hormone is responsible for the development of male physical characteristics, muscle mass, strength, fat distribution and sexual drive. Smaller amounts of testosterone are also produced by women in the ovaries and the adrenal glands. Testosterone production is stimulated by hormones such as leuteinizing hormone further up the chain starting at the hypothalamus in the brain.
To be more definitive, testosterone is an androgenic, anabolic, steroid hormone. ‘Androgenic’ means pertaining to male characteristics and ‘anabolic’ means building up or synthesizing body tissue. ‘Catabolic’ means breaking down tissue. Another important hormone, cortisol, is a catabolic hormone. A ‘steroid’ in broadest terms is a class of similarly structured chemicals produced by the body.
Testosterone is the number one hormone for bodybuilding and weight training, especially for the development of strength and muscle although this is not always the primary goal of weight training.


Anabolic steroids

The use of supplementary anabolic steroids to build muscle bulk and strength has been popular in bodybuilding and other sports requiring bulk and strength for many decades. They do work spectacularly well. That’s why in most sports, taking ‘steroids’ is illegal under the World Anti-Doping Agency protocols, although not all sports are referenced by this organization.
Illegal supplemental steroids include natural testosterone or the very many natural or synthetic molecules based on testosterone or anabolic hormone precursors. Some examples include testosterone enanthate, nandrolone, trenbolone, oxymethalone, stanozolol and the various trade names under which they are marketed. The adverse effects or taking these substances carelessly have been well documented. Although oral formulations of some anabolic steroids are available, they are usually injected once or twice a week.

Growth Hormone and IGF-1

Human growth hormone is produced by the pituitary gland and stimulates the liver to produce IGF-1 which is ultimately responsible for the growth promoting and anabolic effects of growth hormone. Like testosterone, this production declines as we age and is probably responsible for at least some of the decline in muscle mass seen in older people. These hormones seem to have an inverse relation to body fat : the less you produce the more body fat you accumulate. . . so there’s the first call to action.
Enhancing growth hormone and IGF-1 delivery may be possible with nutritional and exercise manipulations. GH and IGF-1, testosterone and cortisol are all increased with intensity of weight training and high-intensity sprint cycling or running.

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Insulin is the storage hormone. The pancreas produces insulin in response to food. When you consume food, enzymes break it down into constituent glucose, fatty acids and amino acids, vitamins and minerals. Insulin responds to carbohydrate and protein by storing glucose in muscle and liver, fat in fat cells and by the utilizing amino acids from food protein in body building and repair. It’s incorrect to think of insulin as only responding to carbohydrate foods because some protein foods such as fish and beef elicit a very strong insulin response in their own right. In diabetes, insulin is either insufficiently produced or is available yet fails to store glucose efficiently. This is called insulin resistance.
Combining pre- and post-exercise foods or sports drinks containing protein and carbohydrate elicits a very strong insulin response in the refueling period after an exercise session. The value of this is that along with the glucose storage and amino acids synthesis in new protein, you get a powerful anabolic, muscle building response. Insulin is an important anabolic hormone. Manipulating insulin is one of the main tools described here for bodybuilding. See further down for nutritional approaches.


Cortisol is a very important hormone that’s for sure. It is produced by the adrenal glands and is often called the ‘stress hormone’ because it responds to stress, either physical or emotional. Cortisol helps control inflammation, makes glucose available by breaking down muscle to amino acids, suppresses the immune system and is likely to enhance fat storage at the expense of protein and muscle. Cortisol rises when blood glucose gets low : in the early morning and during exercise, especially prolonged endurance exercise. Cortisol is a catabolic hormone. In manufactured form it’s called hydrocortisone or cortisone.


Epinephrine (Trade Name Adrenaline)

We all know it as adrenaline but epinephrine is considered the ‘fight and flight’ hormone because it acts quickly on cue to constrict arteries and raise blood pressure and dilate the airways to enable your heart to beat faster and you to breathe more efficiently – all of which are important if you suddenly need to run away from an attacking lion! As well, epinephrine elicits the muscles and liver to give up stored glucose (glycogen) so that you have instant energy to fuel that survival run. In this sense epinephrine is a catabolic hormone like cortisol.



Glucagon could be considered a mirror hormone of insulin. When you fast or eat a low-carb diet glucagon will be more active than insulin because of low blood glucose. Glucagon tells the liver to give up its glucose stores to the bloodstream and also to break down those amino acids from muscle that cortisol sent to the liver to make more glucose. If insulin is an anabolic hormone then glucagon is a catabolic hormone.

Natural Anabolic Enhancement

I trust the bigger picture of hormone action and metabolism is starting to make sense. You can see from the discussion so far that we have a task ahead of us here. We want to keep those anabolic hormones high and the catabolic hormones as low as possible while still providing basic functionality. It’s not useful to regard cortisol or any other hormones as ‘bad guys’ because we couldn’t live without them.
In the ‘natural’ bodybuilding movement and for sports where compliance with drug-testing protocols is essential for competition legality, finding a way of training or eating that will maximize or enhance testosterone and androgen-related muscle and strength is keenly sought. Alas, this is not a process that is easily manipulated and there is much still to learn. However, that has not stopped supplement manufacturers claiming to have products that can do just that with herbal extracts or combinations of vitamins or ‘legal’ steroids. Examples of such products are the herb Tribulus terrestris, zinc-magnesium tablets, ginseng, bovine colostrum, beta-alanine, HMB, and DHEA, a prohormone banned in most sports but not in baseball. Tribulus has become popular in the bodybuilding community even though there is no evidence that it provides any advantage.
A recent study of elite rugby players published in the May 2007 issue of the Journal of Strength and Conditioning Research did not find any advantage in muscle enhancement or performance from supplementation with Tribulus. This seems to confirm the result of previous studies. There are no specific non-food supplements other than creatine that have been shown to enhance bulk and training similar to the anabolic steroids — and creatine is a component of meat foods. Yet even creatine has an uneven performance as a supplement.


What You Can do to Enhance Muscle-Building Hormones Naturally

Here are several approaches to diet and training that can go some way toward maximizing your anabolic hormone response and building and protecting muscle mass and strength. Although the following is based on recent research results, there is still much to learn about the complex web of hormone interactions involved in strength and muscle enhancement, so don’t be too surprised if something changes soon.


Pre- and post-exercise nutrition.

Consume about 20 grams of protein in an easily digested source up to 45 minutes before a workout. Skim milk with a little sugar will do fine. About 20 fluid ounces (600 mls) or a little less is about right. Sip a sports drink during the workout at regular intervals, especially if you go beyond 60 minutes. Within 30 minutes of finishing the workout consume another 20 grams of protein with about 40 grams of carbohydrate. Again, skim milk seems to work well. Choose your favorite protein-carb powder or even a commercial flavored milk if you prefer. Increase the carbs up to about 3 or 4:1 carbs to protein ratio if you’ve had a heavy or long session with cardio or intervals or circuit.
Taking carbohydrate during exercise has been shown to minimize the rise in cortisol (Bird 2006). Testosterone, growth hormone, epinephrine and cortisol all increase during exercise with intensity. With blood glucose topped up, cortisol doesn’t get the signal to supply glucose, so muscle doesn’t get burned up in the process. Even after your session, testosterone and cortisol levels move around quite a bit and testosterone levels may drop. The testosterone to cortisol ratio is the key. Keeping testosterone as high as possible and cortisol as low as possible when you don’t need it is to your advantage.
It’s worth stating that you don’t need any cortisol-reducing supplement tablets. There is no proof that they work and carbohydrate manipulation seems to do the job for little added cost.

Macronutrient composition.

Eating a diet that’s not too low in fat and not too high in protein may enhance testosterone production according to a recent study (Sallinen 2004). A diet that is in the range of 20-25% fat and 20-25% protein should be in the range for this. Fat should be mostly unsaturated fat – nuts, avocados, olive oil, and polyunsaturated and monounsaturated oils rather than saturated fat in meat and cheese. Lean protein is still best. The ultra low-fat Pritikin or Ornish diets or the high-protein low-carb type diets may not be the best choice.


Now I don’t agree with the guys or gals who want to eat 40 percent protein in their diets. It’s way beyond what is scientifically proven to be required, expensive, not necessary and may even be unsafe in the long term. However, heavy weight trainers can probably justify extra protein up to about 1 gram/pound bodyweight. Don’t make it all beef dripping with fat though. Get plenty of white meat, dairy protein and soy as well for healthy eating. Get some advice if you even think you have dysfunctional kidneys. Just for the record, 4 ounces or 100 grams of lean grilled chicken breast or beef has about 30 grams of protein.
Creatine and zinc are potentially important components of an anabolic diet. Creatine builds bulk and re-supplies the phosphocreatine energy system which is important for those fast heavy lifts and zinc is necessary for testosterone production. Meat protein is a good source of both of these elements. Vegetarian bodybuilders may need to ensure sufficient intake.

Workout Strategy.

Heavy lifting and high-intensity workouts raise testosterone, growth hormone and IGF-1 but cortisol goes along with them during intense exercise. This applies to sprints and other high-intensity programs as well as weights. Planning your nutrition is likely to be helpful but for training programs I can’t do better than to quote the review by Kramer and Ratamess in Sports Med. 2005 when it comes to suggesting a strategy in the gym.

“Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth.”

So what does that mean for individual exercises? Okay, at the top end that means heavy squats, deadlifts, and even the more advanced power cleans, hang cleans and pushes or at least some serious hard work at perhaps 5×5 sets and repetitions if you do a standard full-body session with a mix of free weights and machines. Squats and deadlifts are known to be the quickest way to build bulk and strength all round, so try to build these into your program in some form if that’s your objective. Don’t beat yourself up though, the difference is probably not that necessary for someone just doing a fitness program.

Other Tips on Hormones and Muscle Building

  • If you do aerobic training like running or even anaerobic interval training, you’re probably better off doing it on separate days or at least to separate it from your weights session by at least a half day to allow normalization of hormone response. At least one study has shown that a high-intensity cycle session before weight training blunts the testosterone response during the weights session.
  • Cortisol peaks in the early hours of the morning, so many bodybuilders train in the evening to ensure a more suitable hormone profile. This is probably not necessary if you take some carbohydrate before you train in the morning. Even so, trialling different training timetables is worth a try.
  • Alcohol consumption increases cortisol during drinking and even in the withdrawal period, particularly in heavy drinkers. So, no soup for you! However, a glass of wine or a beer in moderation is probably not going to make much difference.
  • poor sleep pattern does not provide an optimal environment for anabolic processes to occur. Human growth hormone is at its peak during deep sleep. Interrupted or poor sleep could be a contributing factor to a less than optimal muscle and strength response to exercise.

Summing Up Hormones and Bodybuilding

If you are looking to make the most all the hard work you put into weight training — and why wouldn’t you — the techniques described above are definitely worth following up. In some ways we are slaves to our hormones, but you can make a difference.

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