The Hormonal Influence Link from Exercise and Diet

We know that regular exercise and good diet strategies work, but there is a complex biochemistry that takes place to make the change. Altering your metabolism by manipulating diet and activity is the overall objective, but understanding how diet and exercise actually do it is the key. Understanding why and how our body changes with the influence of diet and exercise can make all the difference in the world and one can tune and sharpen it for fast, precise results.

Bridging the gap between our efforts to be healthy and fit and what we see in the mirror is a biochemical science that is in motion all the time. In general, we call this our metabolism, and it is an unconscious process. Our metabolism is directed by chemical signals that the body produces in response to our input and expenditure of energy. With the correct inputs and outputs we can direct our body’s metabolism with pin-point accuracy. What we think, how we act, what we do, what we eat, and what we look like is no coincidence. There is a connection.

Connections and communications between our body’s organs has been studied and researched for thousands of years. Connections of the mind-body can be divided into many pathways; conscious, unconscious, neural, hormonal, and neurohormonal. Conscious connections are ones that are thoughts from the brain telling the body to do some type of action. Unconscious ones are ones like your brain telling you to breathe in and out to get oxygen. There are names like central nervous system, autonomic nervous system, sympathetic and parasympathetic modes, but for the sake of keeping it simple, this is a brief over view of metabolism and the connections of exercise and diet.

The nervous system, endocrine system, immune system, digestive system, circulatory system, and the musculoskeletal system all work in harmony and are synchronized by communication. There are many other sub-systems among these systems and they are important in metabolism, but for the sake of brevity these sub-systems will not be discussed. All systems communicate, regulate, and provide information and feedback with chemical and electrical signals from organs, glands, and tissues. These communications are taking place all the time, and are very complex.

This communication, regulation, and manipulation of the endocrine system is the most powerful thing that can change composition of the human body. To be able to manipulate the hormones that the body produces gives one the keys to change. All the exercising and dieting in the world will not change your body if the endocrine secretions are not stimulated to make the body change. Knowing what hormones do can benefit you in the process of transformation. All diet and exercise programs are not equal and their hormonal responses are different as well. This is crucial in being successful and is one of the biggest reasons why most people fail at changing the human body. Knowing everything about the endocrine system is not necessary to change the human body, but a few key functions will need to be understood.

Key endocrine mechanisms and actions that should be learned are ones that deal with energy usage, access, and storage. The hormonal actions that are primarily responsible for weight loss, weight gain, and body composition can be manipulated with diet, supplements and exercise. Knowing how to manipulate these hormones optimally is really the key to effective body transformation.

The combination of reducing body fat, increasing lean body mass, and elevating the body’s metabolism at the same time is actually quite easy when exercise and diet work hand in hand. By increasing the metabolic rate the body normally will reduce body fat as a result, provided that caloric intake is not increased at the same time. In general, any time that exercise is introduced, calorie burning increases to perform the work being done which causes an increase in the body’s metabolism.

Exercise stimulus can be linked to a hormonal response. Depending on the type and the intensity of the exercise, research has shown large shifts in hormonal outputs for increasing metabolism, reducing body fat, and increasing lean body mass. Testosterone and growth hormone outputs are increased from the response of physical stress stimulus. These hormones are being secreted all the time and are working on your body while you are not aware. You don’t build muscle in the gym, you merely create the stimulus to promote and influence key hormones that create the change. Hormones link what you do to how you look. Repetitive exercise stimulus changes the regulation and output of these hormones and over the course of time the body changes. This is the missing link that many fail to understand and why the attempts to change the human physique fall short.

Let’s examine the two types of exercise and their respective hormonal influences. Resistance training and aerobic training, both burn calories while performing the activity, but they differ in their stimulation of key hormones. Resistance training raises the metabolism by creating muscular trauma and breakdown that will need to be repaired. Hormones are secreted and rejuvenation starts. This can last as long as 72 hours or more. This rejuvenation process needs lots of energy to fuel the construction of new muscular proteins. The additional muscle that will be added requires more energy and can do more work the next time you train. Thus, more energy will be spent while you are exercising, while you are recovering, and to maintain the newly acquired muscle, all while you are at rest.

Aerobic training utilizes energy, carbs and fat moslty, to perform work for an extended period of time. As carbs and fat are consumed in the working muscles, hormones are stimulated in response to replace these energy stores in the muscles from our adipose tissue and liver. This is how our fat deposits are reduced from aerobic training.

Both types of exercise stimulus are effective at reducing body fat but each have a different pathway of metabolism that changes our appearance. The most effective training program utilizes both strategies. Resistance training creates anabolism (tissue building) and aerobic training creates catabolism (tissue breakdown). Together these two types of exercise styles work together synergistically which makes them more effective than either of them by themselves.

These are physiological changes that can be measured by the mirror or the scale, but the real magic from hormonal manipulation from exercise is the benefits that these hormones have on the rest of the body’s organs and systems. The brain and nervous system functions are enhanced from testosterone, growth hormone, adrenaline, epinephrine, and other hormones. The heart, lungs, liver, kidneys, digestive tract, immune and lymphatic systems are all tuned and sharpened in response too. This is why people that exercise regularly can and do live longer and have a higher resistance to disease. Not only do you look stronger and healthier but your internal systems are stronger too.

Another way to alter one’s metabolism is by the consumption of food. Depending upon what type of food is consumed; it can be burned, stored as fat, or made into new body components. What food becomes once it is consumed will have a lot to do with what the food composition actually is and what the body needs. The old saying of "You are what you eat" has real meaning.

For example if one were to consume foods that are high in saturated fats and refined sugars, you can guess that the food will be processed into energy storage to be used later for energy output during activity. If the food consumed has high nutrient content and protein, which are components needed for energy conversion, tissue replacement and rebuilding, the food is utilized to rejuvenate and replace the body’s active tissues.

Protein, carbohydrates, and fats have hormonal responses when introduced to the digestive system but not all of them are the same. Certain amino acids in high concentrations from complete proteins can increase growth hormone output which raises metabolism. Hormones are made from proteins so it should be understood that a diet that is abnormally low in protein can have adverse effects because of the lack of materials to rebuild the body or even manufacture the tools (hormones) that start the actions of rejuvenation.

Carbohydrates can influence insulin to a greater or lesser extent depending on the source and type of carbohydrates. Insulin is a hormone that affects storage and uptake of nutrients. Carbohydrates that are refined and enter the circulatory system rapidly from the digestive tract elicit a large rapid release of insulin which signals the rest of the body to pull blood sugar (glucose) from the blood. If the glucose depots (muscles and liver) are full, the glucose is then converted to fat and stored in the adipose tissue. This roller coaster effect of insulin feedback in response to elevated blood glucose causes hunger mechanisms to be activated. When too much insulin is secreted, blood sugar levels drop too low and the search for food is stimulated. The more insulin secreted in the presence of high blood glucose the more the body will store the energy in the cells and create a vicious cycle of eating.

Complex carbohydrates on the other hand, take longer to breakdown in the digestive tract and have a much slower absorption rate into the blood stream which does not have this roller coaster effect. Control insulin with your diet and you can control hunger, storage, and the food energy conversion rate. This is one of the biggest keys to weight management. This basic science of blood sugar control is the basis for many diet books on the market today.

Years ago fat was thought to be the main culprit to obesity, but now we understand the role of fat in the diet. Science is uncovering which fats are actually of benefit to a healthy metabolism. If fat is not in the diet there will not be any fat soluble vitamins (A, D, E, K) that are crucial to almost every metabolic action in the body. Also, there has been recent scientific research that indicates that certain fatty acids (CLA, GLA, omega 3’s, etc.) have hunger busting, thermogenic, and even anabolic properties. Fat is not just fat anymore. It is not well understood how these fats do these things but the actions of these fats are well documented and are now widely utilized for health enhancement.

Good nutrition provides construction materials for replacement tissues, fuel to be converted to energy for work by the body and internally for the body’s systems to perform work. Good nutrition also provides catalysts (vitamins, minerals, trace elements, etc.) for the billions of chemical reactions that are taking place all the time and providing protection from the bombardment of free radicals that are produce in our own bodies or are contacted via the environment.

The diet-exercise-hormonal link has been well established. This is a brief overview of what we do and what we eat that makes up who we are, how we look, and in general how our metabolism is regulated by chemical signals. Understanding the endocrine system and how it is influenced by food and exercise bridges the gap of information that will make or break you in your quest for higher health and fitness.

It should also be noted that the absence of these elements (regular exercise and good nutritional intake) are definitely detrimental to the body and deregulation of these hormonal pathways can lead to premature aging and disease. Science has explored and uncovered the pathways that make up our physical existence now it is time to take this information and utilize it for our own benefit.


These resources are for the purpose of personal trainer growth and development through Continuing Education which advances the knowledge of fitness professionals. This article is written for NFPT Certified Personal Trainers to receive Continuing Education Credit (CEC). Please contact NFPT at 800.729.6378 or [email protected] with questions or for more information.