Should You Run on an Empty Stomach?
Understanding how the body utilizes energy for exercise
The answer, like most things in life, is complicated. It depends and varies from person to person. If your goal is weight loss, then running on empty, if done right, may not be such a bad idea after all.
Quite many runners who choose to run in the morning prefer to eat after completing their runs and not before. This whole thing of running without eating for an extended period is called fasted running.
Before we dive into the whole concept of fasted running, it is useful to understand how our body utilizes energy briefly without going into the extreme science of it.
Adenosine triphosphate (ATP)
ATP is the body’s biochemical way to store and transport energy. Long story short, it is the energy-carrying molecule found inside our cells. It utilizes chemical energy from food to fuel our bodies.
ATP needs to be synthesized to get energy using it.
ATP is the gas in the tank.
Glycogen
These are stored forms of carbohydrates in the muscles. When we run, the body uses energy from primarily two sources- fat reserves and glycogen reserves. When we make short runs or exercise with lower intensity, more fat is burned relative to glycogen; however, when we make long runs or high-intensity exercises, more glycogen is consumed relative to fat.
Therefore, in other words, when the body needs an immediate source of energy (ATPs), glycogens are used.
It is important to note here, even though the fat burned is less relative to glycogen in long runs, essentially more fat is burned in long runs compared to short runs.
For further understanding of the muscle metabolism, you can check out the article linked here.
Pros and Cons of fasted running
In Fasted running, we are going for a run without eating for an extended period. The result is that our body works in a glycogen depleted state. This means no glycogen reserves are available to use as fuel. So what happens next? Our body starts to use fat reserves as the source of energy instead.
Burning fat is a slower way of generating ATP, but it is particularly helpful for the body during long runs.
Benefits of fasted running:
1. Increases the body’s utilization of fat.
2. Reduces the risk of cardiovascular diseases by lowering cholesterol.
3. Reduces risk of runner trots and stomach related issues.
Drawbacks of fasted running:
- Long fasted runs could lead to depletion of muscle mass, which in turn could affect the body’s metabolism.
- Recovery could be slower.
- Lack of immediate fuel reserves (glycogens) could affect your speed/intensive workout goals.
Fasted running enhances mitochondrial biogenesis
Dropping big science words here. But to understand the energy utilization system of our body, we need to know what Mitochondria is.
In layman terms:
Mitochondria are the batteries that energize our muscles. So the synthesis of a more significant number of these mitochondria is what we should aim for in training to bring up our potential to utilize oxygen.
Fasted running has shown to increase the generation of mitochondria more effectively compared to usual runs. This being said, research is still under progress to accurately study the genesis of mitochondria and its relationship to faster running.
How long should a fasted run be?
The length of the run can be decided based on the intensity at which you are running.
Since fasted runs are done in a glycogen depletive state, high intensity runs would need to be very short due to the absence of immediate sources of energy. However, slow-paced long runs can be done better with fasted running. The rate of use up of energy is less, and the body has more time to use the burning of fat resources as a primary source of energy, which is more time taking way of synthesizing ATPs than burning glycogen reserves.
How frequently can we attempt fasted runs?
Going for one-third to one-half of your runs as fasted runs would be a decent start. If you are more focussed on building endurance, then near half of the runs could be fasted.
It is a good idea to try and give fasted running a chance to see how it feels. I personally just yesterday completed my first fasted run, and to be honest, it feels kind of good and much lighter.
The choice to practice fasted runs is a personal decision. Running the right way consistently, regardless of whether you eat or not, will end up benefitting you and provides clear health benefits by improving the cardiovascular system and oxygen utilization.
In the end, each body is different and responds differently. Don’t let me be the judge. Go ahead, give this run a try and see how it feels and works out.
