Metabolic processes are what keeps us alive at the cellular level. Dr. Peter Attia provides an interesting personal study on the effects of food choices on metabolism and how the body uses the fuels it is given.
For all those that don’t believe that we are what we eat, this video may provide personal evidence that daily food choices are important in the overall picture of health and wellness. So sit back and enjoy…this will change your outlook on life!
You may remember this term from biology class. ATP or adenosine triphosphate is the primary fuel needed by all cells and is generated by the body on a continuous basis. ATP is essential for metabolic function and transports chemical energy to all living cells at the molecular level. This stuff is vital for our existence! Think of ATP as a battery. The battery is fully charged when it has three molecules of phosphate ( the triphosphate form). Each time the adenosine looses a phosphate the molecule give up energy and the battery looses some of its charge. And just as it looses energy by giving up a phosphate, it is recharged when a phosphate is added back. So this substance is continuously recycled through the body constantly providing energy and being recharged. On average, the human body contains about 250 grams of ATP and turns over its own body weight in ATP each day! That’s a lot of recharging and discharging of these batteries.
Two main sources of ATP Generation: Glycolysis vs Ketosis
Our primary source of energy is from glucose which is derived from carbohydrates. The process is called glycolysis. This is something that most of us are aware of and recognize that if you are expending large amounts of energy, that eating carbohydrates will help refuel you. The glucose we therefore need to run the body comes from either the foods we eat directly, or from glycogen stores found in the liver. There is also glucose stores found in the muscle cells which is available but to a lesser degree as it is conserved more for muscle function.
Our secondary energy source, and one that we generally do not focus on in typical nutritional and dietetic discussions, is ketone bodies. This process is based on ketone utilization and is referred to as ketosis or beta-oxidation. This energy is derived from our fat stores and produced in the liver. The thing with ketone generated energy, is that it is something we create by not eating. This process does not start to fully activate until after at least 36 hours of fasting. A state that most people rarely reach in our food centric culture. There is another way to reach some level of ketone generated energy use and that is through a ketogenic diet which is a severely carbohydrate restricted diet with low to moderate protein and higher fat consumption (up to 80 percent of calories for those serious about this approach). I will talk more about tis type of diet later, but for now want to focus on fasting to reach this state.
You are probably asking yourself why this is relevant to you and what does it mean for your health. Well the whole goal of fasting and a carbohydrate restricted diet is to aid the body in balancing how it uses energy.
What is Glycolysis?
Glycolysis is the process where glucose is converted into ATP. The following video provides a simplified overview of the process. The interesting thing with this mode of energy production is that the energy yield is very low. For an investment of 2 ATP the process only yields 4 ATP for a net gain of 2 ATP.
You could look at this yield as a 100 percent return which I guess is a good rate for energy production. But let’s look at the fat burning mode next.
What is ketosis?
Ketosis is the metabolic shift from using glucose as the primary fuel for the body to ketone bodies as the primary fuel. The actual process that uses ketones is called beta oxidation.
Ketone bodies are molecules that are created by the liver from fat stores within the body. They are produced when there is a limited availability of carbohydrates or when carbohydrates cannot be used effectively and become an alternate source of energy for all the body systems that normally require glucose energy sources. For example, after an over-night fast, ketone bodies supply 2–6 percent of the body’s energy requirements, while they can supply up to 30–40 percent of the energy needs after a 3-day fast. It is this state of energy production that results in rapid fat consumption and weight reduction. The following video provides a simplified explanation of beta oxidation. The amazing thing about this process is that for the same investment of 2 ATP the process will yield over 120 ATP!
How do these two sources of ATP compare
Now although this is a significantly more abundant supply of ATP compared to glucose use, it is a slower or less responsive process. So when we need quick energy, the glucose cycle is a more readily available and quicker responding cycle. However, as a more efficient source of energy, the ketone path provides an abundance of ATP but is slower to trigger because of the need for fatty acids which are driven through a process described in the next section.
So the best way to compare the two energy supplies is to look at the ketone based supply as the base energy in an electrical grid which is usually a system like nuclear energy. This source takes a long time to ramp up, is very stable once activated, but does not have a quick response time to increased energy demands. The gap that is created from peak energy demands is closed by quick reacting energy sources such as a gas powered plant which can be turned off and on very quickly. This is similar to the glucose cycle.
Next I will talk about influencing the glycogenic/ ketogenic balance to manage where your energy supply is generated.
