Fat metabolism provides an essential fuel for satisfying physiological needs for your entire body. It is your body’s largest energy reservoir and has significantly more available energy to meet physiological needs than carbohydrates. Just stop and think about that for a second! Personally, I think that (along with so many other things about the human body) is fascinating. If I can get my body to break down and use body fat for fuel, I’ll never run out of energy to do what I want to do. The compliment to that is constantly burning body fat could result in looking the way you ultimately want to look with the physique you want. The inability to satisfactorily metabolize fat for energy comes with the high likelihood of having undesirably high levels of body fat and increases the risk of obesity and related health conditions. We all know that regular exercise lowers the risk for obesity. We also now know that regular exercise is very health promoting because of its ability to improve fat metabolism. Regular exercise improves the capacity to burn fat; improving the capacity to burn body fat for fuel lowers the need for carbohydrates to be used as fuel and ultimately results in enhanced exercise capacity and endurance.
Fat Metabolism & The Human Body
Approximately 50% of the body’s fat is subcutaneous fat (meaning it is just beneath the skin). Subcutaneous fat provides a source of fuel for muscles as well as a temperature regulating blanket for the human body. Most of the remaining body fat is visceral fat – the fat that primarily surrounds our organs (helps to maintain the organ’s temperature and provides a source of energy for body tissues). The primary storage of body fat cells is in the form of triglycerides. These fatty acids are metabolized based on the energy demands of the body, such as during exercise. Essential fatty acids (which are only obtained through the diet), have additional benefits to the body in addition to producing energy. For example: omega-3 fatty acids have strong anti-inflammatory affects in the body. Humans also have stores of intramuscular triglycerides that provide an excellent and convenient source of fuel for the mitochondria. The mitochondria is the hub of the cell where ATP is produced and is the main source of energy in Type I (slow twitch) muscle fibers. The smaller intramuscular triglyceride stores are metabolized first, before using triglyceride from the larger stores of general adipose tissue that require fatty acid delivery to skeletal muscle through circulation. Obese individuals have significantly larger intramuscular triglyceride stores and a reduced capacity to metabolize these triglycerides during exercise, as compared to nonobese individuals.
Lipolysis is the breakdown of triglycerides. It separates fatty acids from a backbone which allows the now free fatty acid to be transported through the blood, bound to a transporting protein to skeletal muscle where it is metabolized for energy. We want to maximize this process as efficiently as we possibly can. Hormones regulate fat metabolism based on the body’s energy demands. Higher energy demands during exercise cause the release of epinephrine (from the adrenal glands), which facilitates lipolysis.
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