Intermittent fasting is a well researched approach to restricting calories to improve the overall health of an individual. Intermittent fasting is a pattern of eating that cycles between periods of eating and fasting. It is important to note that intermittent fasting is not a diet, but merely a pattern of eating. In this article, I will do my best to break down what is going on in the body during the fasted state.
In simple terms, the body converts food into energy to perform a variety of different functions. We call this wide range of biochemical processes metabolism. Metabolism can go one of two different ways. It can either build up substances in the body (through a process
called anabolism), or it can break down substances in the body (through a process called catabolism). When we eat more food than our body needs, we become anabolic, or substance building. We are taking the excess energy, or food brought in and storing it in the form of fat. The body does this to build up its energy reserves. Conversely, when we consume less than the required amount of energy needed, we become catabolic, and begin to break down our fat to produce the energy our bodies need through a process called ketosis.
The first step in any fast is to force the body into ketosis. Ketosis happens once the body has used up all of its primary stock of glucose (sugar), and shifts to a catabolic mode of energy production. Humans store the bulk of their glucose in the liver in the form of glycogen. In order to lose weight and burn fat we must use up our stores of glucose in the
blood and deplete our glycogen reserves in the liver. On average, our bodies enter the “fasting” state eight hours after our last meal. At this time, your body begins to use its glucose stored in the liver for energy. Once you use up your glucose stores, your body will then switch to a metabolic mode in which fat-derived ketone bodies and free fatty acids are used as energy sources.
Why Do Our Bodies Go Into Ketosis?
Our bodies, when depleted of food, must protect the most important organ necessary for survival, the brain. Studies have shown that when mammals undergo severe caloric restriction, the size of most organs shrink, except the brain. This would imply that brain function under conditions of food scarcity is very important.