You want to do sports on an empty stomach? Some people are convinced of the advantages of this technique and the miraculous effects it has on fat burning. Others are more cautious because of the consequences on health and muscle deconstruction. We will explain what this is all about and on which points you should remain vigilant.
You wake up, get up, and slip into your sports clothes without even thinking. And off we go for the work-out or even for a little endurance race. And you say But that’s completely crazy!, right? Here are the pros and cons of fasting sports.
1. Energy intake: how does it work?
Old, young, woman, man, thin, fat, trained, not trained… It doesn’t matter: when it comes to energy intake, every organism works the same way. The only difference? The processing of energy from food does not work as efficiently from person to person.
But how does energy intake work and what does it have to do with the subject?
As soon as you train, your body uses 3 different energy reserves to guarantee your performance. When none of these reserves are available, then the body can rely on a 4th reserve in case of emergency:
The phosphate reserves: They are the first reserve the body has at its disposal. They separate into adenosine triphosphate (ATP) and creatine phosphate (CP). Unfortunately, these reserves are very small and therefore empty quickly. They are very important, especially for sprinters and power sportsmen and women, in order to guarantee maximum performance.
Glycogen reserves: Glycogen is the stored form of carbohydrates. The production of energy from carbohydrates is called glycolysis. Glycogen reserves are made available to our body in sufficient form after 10 seconds. A difference is made here between anaerobic glycolysis, when oxygen is not used to produce energy (for short and intense efforts such as HIIT training), and aerobic glycolysis, when oxygen is used (for endurance sports).
Lipid reserves: yes, fatty acids are also called upon as soon as you start training. The time it takes for the stored lipids to be converted into energy for training is a little longer in comparison. That’s why fat reserves are not very efficient for quick energy production. However, for endurance sessions of more than 20 minutes, these reserves are the most efficient energy sources, because they are relatively large. This form of energy production is called fatty acid oxidation.
Proteins: the last resort. When all your reserves are depleted, your body relies on protein to produce energy. To do this, your body uses your muscle mass and slowly starts to break it down.
2. What happens when you train on an empty stomach?
As soon as you start exercising, your body produces energy following a specific pattern. The first 3 energy reserves are activated at the same time but are made available after a variable period of time. In the first few seconds, your body uses the creatine reserve for short, intense exercise (e.g. the first few metres of a sprint or strength training). For longer sprints or HIIT training, the glycogen stores take over, without using oxygen. However, this creates lactate, which is the cause of over-acidification of the muscles. That’s why you can’t, for example, hold out after a sprint of up to 200 metres.
For longer sports such as running, cycling or cardio, the intensity is lower. Here, the body concentrates on glycogen reserves by using oxygen so that it can continue its activity for much longer. Fat reserves take a relatively long time before they can be used, but deliver energy for a long time and consistently.
In order to be able to convert fat into energy, your body needs to have carbohydrates available. And usually your reserves are sufficient for this, but it is still a good idea to eat a little something before training.
As soon as you train and sell it empty, your body has less or no carbohydrates available. So it needs to get energy from fat. Except that it still needs carbohydrates, at the risk of getting its energy from the proteins in your muscles because it can’t process fats properly. So your body partly deconstructs your muscles, but also learns to use the free fatty acids in your muscles efficiently.
How do I know my glycogen stores are empty?
It’s hard to know if your glycogen stores are completely empty when you get up early in the morning to train on an empty stomach. It all depends on what you ate the day and night before.
If you had a pasta party the night before, then your glycogen stores will still be full the next morning. On the other hand, if you had a low carbohydrate diet the night before, it is very likely that your glycogen stores have been depleted.
3. pros and cons
The benefits of training on an empty stomach are significant. With regular fasting training, the body learns to use fat reserves faster and more efficiently. Rather useful for weight loss.
Jogging on an empty stomach, for example, can help your body prepare for long runs and thus improve the production of energy from the available fat reserves. It also teaches you how to make better use of available energy sources so that the stocks are emptied out more slowly.
Of course, this does not mean that your love handles will automatically melt away. The first thing you use for energy production are the free fatty acids in your muscles.
It is good to remember, however, that if you exercise on an empty stomach, you won’t be able to use your performance potential to the full. This is why it is difficult to effectively improve performance with empty glycogen reserves.
Training on an empty stomach can be counterproductive if you want to lose weight. Sport on an empty stomach often leads to cravings. And if you eat more than you spent on sports, you will end up gaining weight instead of losing it. Since your workout is less intense than if you had breakfast or a snack before the workout, you will eventually burn fewer calories.
4. Tips for exercising on an empty stomach
To begin with, this type of training is not suitable for everyone. Some people suffer from circulation problems just after waking up. In which case, jogging or doing hard sports on an empty stomach is really not a good idea.
On the other hand, it is advisable to eat a little something for breakfast and drink enough. Just a banana, a Paleo-Bar and a glass of water will make a considerable difference to your performance.
It’s all about balance
You want to improve your performance but also want to train to burn fat? Then you can, for example, train twice a week after breakfast with full glycogen stores and once a week on an empty stomach. This way you have sufficient opportunity to reach your full potential and improve your performance while melting fat.
5. Our bottom line
Sport on an empty stomach is not for everyone. Here is a small overview of the pros and cons:
- Training on an empty stomach promotes the use of fat as an energy source.
- Don’t expect incredible performance during training without eating.
- It is only partially suitable for weight loss.
- Can lead to cravings.
- May cause circulation problems.