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Are You a Sugar Burner or a Fat Burner?

January 6, 2015

To build muscle you must have an adequate supply of protein in the blood stream to nourish the cells of the body. The more muscle tissue you tear down from training the more protein you must ingest to help repair the damaged tissue. Protein is the most important substrate for the body. Protein is the only substance that repairs and rebuilds the cells of the body, carbohydrates and fats only provide energy.

Muscle Metabolism

Fat and carbohydrates are two fuel substrates that provide short to long term energy.

Fat can be divided into the following categories:

Simple Lipids: Commonly referred to as triglycerides. Triglycerides are esters of fatty acids and glycerol.

Compound Lipids: Phospholipids that include lecithin, cephalins, and sphingomyelin.

Derived Lipids: Phospholipids that include glycerolize, sterols, carotenoids, and the fat soluble vitamins A, D, E and K.

Sugar is categorized into the following:


Commonly known as long chain sugars. Complex carbohydrates are made up of many glucose molecules that are strung together which take longer to digest, depending on the length of the chain.
Simple sugars are one to three glucose molecules bound together. Simple sugars are absorbed very fast in the intestines.

Sugar comes in many different forms; sucrose, lactose, glucose. All carbohydrates are broken down in the body to form glucose. Glucose is an important energy source for the body. Without proper glucose metabolism the body can develop serious problems. When glucose enters the blood stream it first goes to the central nervous system to supply energy. Excess glucose that is not needed for the CNS is immediately stored in the liver or muscle in the form of glycogen. If the liver and muscle storage depots are full then the excess glucose will then be converted to fat and stored in the fat depots throughout the body. It is important to maintain proper glucose levels in the body but if you ingest too much sugar, you will store too much fat and, possibly develop diseases associated with high levels in the bloodstream. Among these are diabetes, heart disease, and high cholesterol.

Sugar metabolism can be affected in a negative way if the body gets depleted of its glycogen stores. When the glycogen stores become depleted the body has to resort to burning muscle proteins to be converted into glucose (gluconeogenosis). Burning muscle protein means burning valuable muscle tissue resulting in loss of muscle size. If the body is burning muscle proteins for too long of a period it could potentially damage the liver. The reason why the body converts protein (muscle) into glucose is because the CNS, brain and heart must have glucose to survive. For people who restrict calories usually end up in a catabolic state, resulting in the loss of muscle tissue and the ability to burn fat.

Putting it all together

When the muscle begins to heat up (increased respiration) and if the oxygen demand is not too high then fat is released and is allowed into the muscle cell to be utilized as energy. As long as oxygen is present in the muscle cell then fat can be burned. This is an aerobic process, known as aerobic metabolism.

The thermogenic effect of the muscle results in a triggering affect of the fat cells receptor sites, the “doors” to the fat storage opens and allow fat to enter into the muscle via transporters. Once in the cells, the fat must pass through a series of aerobic enzymes that breakdown the fatty acids into single molecules followed by a couple more enzymatic reactions. Ultimately the fat molecule is burned up by the mitochondria of the cell and ATP is formed for energy. As long as oxygen is present in the muscle cells, then cell fat can be burned. This is an aerobic process known as aerobic metabolism. When the intensity becomes greater than the oxygen demand sugar metabolism takes over.

Sugar metabolism starts when the intensity of the exercise exceeds the demands of aerobic metabolism. Weight training, and sprinting are two great examples of sugar metabolic exercise. When a person weight trains they lift a weight that demands a lot of energy. To get the muscle to contract with an opposing weight against it forces the respiration rate of the muscle to rise dramatically and to alter a shift in the oxygen demand. Without oxygen the muscle begins to shut off. When the muscle shuts off the contraction ceases. Before the muscle shuts off it is still working on its reserves to produce energy. The muscle uses sugar to produce energy for short duration of moderate to high intensity exercise, this is known as anaerobic glycolysis. Anaerobic glycolysis only lasts for a short period of time about one to twenty reps of a weight lifting set. By resting for about six deep breaths allows the body to get oxygen back into the blood stream and allow the person to perform another set of the resistance.

Blood sugar is burned off first during the first few sets of the exercise. After that, it is up to the stored glycogen in the muscle cell to keep up with the short-term energy system. Aerobic enzymes will also get bigger the more you challenge the cardiovascular system during aerobic training. What this means is that when you are finished with an exercise bout and you eat carbohydrates again, later after the workout, the muscles will be able to consume more sugar and store more of it in the liver and muscle for the next time you workout. Aerobic enzymes will also get bigger the more you challenge the cardiovascular system during aerobic training.

What is the best for burning fat- aerobic exercise or resistance exercise?

I say resistance exercise is the greatest fat burner of all. The reason why resistance training is the best is because it produces the greatest thermogenic effect. A thermogenic effect is when the muscles heat up and become more permeable to allow fat, sugar, amino acids, vitamins & minerals, water into the muscle cell. The key to keeping fat off the body is to allow the muscle to burn it up. If the muscle produces a thermogenic effect for long periods of time, say two to six hours after exercise, then the ability of burning fat becomes that much greater.

The difference between aerobic and anaerobic exercise is that aerobic exercise is a good for burning fat while you are exercising within the aerobic levels of the intensity. Meaning as long as your body is working within a certain heart rate for a period of time (30 to 60 minutes) and you are able to sustain the activity without stopping then you could be burning more fat than sugar. However, once you stop the aerobic activity fat metabolism halts. Now when you perform resistance training, the primary fuel you are burning is sugar and not fat. But when you finish the anaerobic exercise and you are resting, depending on the intensity of the exercise, your body will increase in heat producing a greater thermogenic effect.

Here is the best part, when the muscles are exhausted due to moderate to high intensity exercise and there is a lot of repair needed to the muscle tissue, the body, responds to the need by allowing the receptors of the muscle cells to open and stay open to allow fat to enter into the cell to provide continuous energy for the depleted muscle.

This process can lasts from two to six hours after a resistance training event, depending on the amount of muscle used and the intensity of the exercise. Resistance training has the ability to burn fat much longer than aerobic exercise making it the best way of burning overall body fat. Aerobic exercise only produces a short duration of fat burning, and the more aerobic fit a person becomes the better the body becomes at conserving fat to be burned. The net loss of fat burn was less than when the person was unfit. If resistance training is performed correctly then the person will never adapt to the exercise allowing for a continuing thermogenic effect. However, if you overtrain and/or do too little then you compromise the whole system. Aerobic and anaerobic training are essential for activating muscle tissue. With True Bodybuilding if the exercise programs are done correctly then the cardiovascular training is built into the exercise, therefore, doing extra aerobic exercise is not necessary.

Exercising on a regular basis will help increase the activity of the muscle and help develop the aerobic and anaerobic enzymes of the muscle. The bigger the enzymes become the greater amount of fat and sugar the muscle can consume and burn. Also, the furnace (mitochondria) of the cell gets bigger in size allowing for a greater ATP (adenosinetriphosphate) production. ATP is the high energy compound that sustains life.

Not everyone is created equally. Some people are just born with superior genetics that allows them to metabolize fat and sugar at a high rate and activate more muscle tissue, while others have a hard time trying to activate muscle and metabolize fat and sugar. It is written in everyone’s DNA how many muscle cells a person will have and how big the aerobic and anaerobic enzymes and mitochondria’s in the muscle cell will get. Genetics play a big part in how successful your training efforts will become.

Daryl Conant, M.Ed, is an Author, Exercise Physiologist, Natural Bodybuilder, and owner of Fitness Nut Enterprises in Kennebunk, Maine. He has devoted his life to the pursuit of fitness and nutrition. Over the past 25 years, Daryl has taught thousands of people how to exercise and eat correctly. He is available for consultations and can be contacted at www.

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