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Build Muscle by Manipulating Hormones

Testosterone, Growth Hormone, Insulin


Updated April 30, 2014

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.


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.

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