There are many arguments, especially those based around Paleo diets, as to whether or no fat is the preferred fuel for the body over glucose. So, what is the difference between fat and glucose when it comes to our body’s fuel and energy levels and do our body’s prefer one over the other?
We depend on our daily food intake to replenish our daily fuel supply and the body requires this fuel in order to function at a normal rate. Our body’s fuel takes on three forms: Carbohydrates, which are converted into glucose, fat, and protein. The body can also store some fuels in a form that offers our muscles an immediate supply of energy.
What is glucose and how do our bodies use it?
Glucose is derived from carbohydrates, such as sugar and starch, and is the body’s principle source of energy. Glucose can immediately be used as fuel for the body or it can be sent to other parts of the body, such as the liver and muscles, where it is stored as glycogen. The body’s liver can convert the glycogen back into glucose as well, but it is then directly released into the blood stream in order to maintain the bodies blood sugar level also known as blood glucose levels.
When you are exercising, your muscles pick up a portion of the glucose and use it as energy in addition to their glycogen stores. Blood glucose is also the most significant source of fuel for the body’s brain, both while exercising and when at rest. The body requires less oxygen to burn energy from glucose compared to energy from fat. Your body is constantly using glucose and working to replenish your glycogen stores. Both, the amount of carbohydrates you consume and the amount of physical activity you endure, effect the size of your glycogen stores. Your body is limited on the amount of muscle and liver glycogen it can store, at approximately 1,800 to 2,000 carbohydrates or roughly 90-120 minutes of vigorous physical activity. As you exercise, your reserve continues to deplete and your body relies more on blood glucose to meet your body’s energy needs.
How fat is used for energy
While glucose is the principle source of energy for our body’s, Fat is the most concentrated source of energy and supplies more than twice the amount of energy of carbohydrates (glucose) and protein. As you exercise, stored fat in the body is broken down into fatty acids, which are then transferred through the blood to the muscles to be used as fuel. The process is however, slower than that of carbohydrates being broken down into fuel. During the process, fat is also stored within the muscles where it can be easily accessed during vigorous activity. Unlike the limited storage of glycogen, fat has a virtually unlimited supply of energy.
Fat is also a more efficient fuel in comparison to carbohydrates, mostly because carbohydrates must be stored along-side water. If our bodies were to the same amount of fuel from carbohydrates as it does fuel from fat, we would be double our body weight, due to the added weight of the water needed to store the carbohydrates. Thus leaving glucose as an unrealistic source of all our bodies energy supply. The body also continuously converts and stores excess calories from all of the named energy sources as body fat that we in turn burn off as an energy source. Fat provides a much more concentrated amount of energy in comparison to glucose and it aids in endurance by preserving glycogen reserves within the body.
Protein used for energy within our bodies
As for protein, it doesn’t stand much of a chance in this argument. Our body’s do not maintain official reserves of protein for later use as energy. Protein, is more used towards building and maintaining body tissue and synthesizing certain hormones and enzymes. Typically, protein only meets 5% of the body’s energy needs, with the exception of when glycogen is depleted within the body, in which case muscle is broken down and used as energy within the body.
Overall, fat is the most substantial source of energy for our body’s for many reasons.
In conclusion, our body’s need both Fat’s and glucose in order to function properly. Both supply our body’s with different energy sources, of which we need. In the long run, they work together. Fat helps to reserve the glucose stores within our body that we count on to supply our brains with an adequate amount of oxygen. Which otherwise, would quickly deplete when solely depending on glucose as a source of the entire body’s energy supply. Meanwhile, fat can be stored in much easier quantities and doesn’t deplete in the same sense as glucose, providing us with a longer lasting supply of energy. Fat is also a more concentrated form of energy providing your body with the energy needs for longer periods of activity.