Fasting exercise - a myth or an effective way to lose fat?
People's approach to sports and exercise varies, some prefer modern fitness centers, others feel better at home. In addition to intensity, however, there is also a difference in attitude to training time. There are definitely supporters of exercising in the afternoon, but many fans also have a morning fitness.
One of the arguments for morning sports is training on an empty stomach. It is believed that "fasting" a person burns more fat and loses weight faster. But is it really so? Are we going to set the alarm for an earlier hour?
Morning workout burns more calories
The human body needs energy for physical activity, which it obtains from diet. More precisely, it is represented by three macronutrients - proteins, carbohydrates and fats. It is the carbohydrates in the diet that are a quick source of fuel because they are broken down into glucose, which travels through the bloodstream. There is also a connection with carbohydrates that the body takes energy from stored carbohydrates and fat during training on an empty stomach, and not from food that you would otherwise have just eaten. So should we all exercise in the morning before breakfast?
As already mentioned, carbohydrates are broken down into glucose, which is a source of energy. In addition, however, the body can store it in the liver and muscle tissue in the form of glycogen. It is a fast source of energy, but after a night without food, the sugar reserves in the liver are quite depleted. If the body does not have energy from available carbohydrates, it uses fat as a source of fuel.
This finding is not just the result of knowing the processes in the human body. This has been confirmed by several studies, such as a 2017 study from the University of Bath. The researchers found that several genes present in fat metabolism, glucose transport, and insulin signaling "behaved differently" during exercise after a meal and on an empty stomach. Physical activity on an empty stomach triggered certain genes in obese men that were able to accelerate fat burning. According to another study from 2013, active men can burn 20% more fat on an empty stomach than after breakfast.
What happens to the human body when we exercise on an empty stomach?
Fat cells are broken down - lipolysis.
Fat is used as fuel.
Hormone levels that support the use of fat as a fuel are rising.
Degradation of fats in the abdomen is promoted.
Abdominal blood flow increases.
Early training with an empty stomach is better according to this, and scientists are proving it. If it were that simple, this article would just end, everyone would exercise in the morning, and the gyms could close peacefully in the afternoon. However, the whole topic is a bit more complex.
Exercising on an empty stomach is great, but…
Some people exercise in the morning because they prefer to "get it out" before work, others want to lose weight primarily. Before you go for a run or "lifting dumbbells" before sunrise, you should consider a few interesting findings.
Fasting training is beneficial in terms of growth hormone growth and insulin sensitivity. These processes can result in fat loss, but keep in mind the other two facts:
Intense fasting training can have an impact on your muscles - this is the catch you may have been waiting for. During a demanding morning workout before breakfast, muscle loss could occur because the body can break down amino acids to maintain blood glucose levels. Fast running or strenuous strength training uses more glycogen than fat, and it doesn't matter if you have an empty stomach. This is also proved by a study by Schoenefeld from 2011, which will be of particular interest to bodybuilders and athletes interested in building muscle mass. Fasting training significantly affects the protein reserves that you have gained through diet and exercise. It can cause their loss by up to 10.4%.
We burn glucose and fat throughout the day - remember that the amount of fuel from glucose or fat depends on all energy "requirements" throughout the day. However, fat burning is more about total energy expenditure. Yes, you can burn a little more fat by training on an empty stomach, but from a general point of view, it probably won't be enough to solve the problematic fat.
Common truths and rules without relevant evidence become only "hypotheses." It is up to the research to analyze and validate theories that "logically" make sense. Training on an empty stomach triggers other genes in obese people, but exercise before breakfast may not be a universal guide to fat reduction for everyone.
Evidence of this is also the results of research from 2014, which examined the hypothesis of the effectiveness of fasting exercise. The aim of the researchers was to compare the differences in fat and "non-fat" tissue of young women after aerobic training on an empty stomach or after a meal.
Participants were randomly divided into "fasting" and "after meals" groups. It should be noted that all respondents followed the diet plan and were in caloric deficit. Weight and adipose tissue loss were found in both groups. Wondering how much better the group that trained on an empty stomach was? According to the results, there were no significant differences between the groups. It is true that only young women were involved in the research and their number was also not particularly high (20 respondents). On the other hand, it can mean that if you follow a reasonable diet and exercise, it doesn't matter if you go jogging before or after breakfast.
Less strength during exercise
Another argument against fasting training is less strength during exercise. Using fat as energy requires more oxygen, so breaking down fat takes longer compared to carbohydrates. To maintain a high intensity, the "rate" of fat metabolism is slow. This means that your training may be weaker than if you had eaten before.
The evidence is the results of a study from 2019, which compared the performance of squats and bench pressures after a carbohydrate-rich breakfast and a "on-water" breakfast. The task of the participants was to perform 4 series of squats and pressures on the bench at the level of 90% of their maximum for 10 repetitions (10 RM - repetition maximum). The result? Participants who drank only water in the morning and did not have breakfast were found to have a 15% reduction in squatting strength and a 6% reduction in bench press. The results show that training associated with lifting higher weights or requiring strength is probably more sensible and effective after a meal. It is possible that you will burn more fat, but your performance may "go down", which you probably will not like emotionally, and in addition you are at risk of injury due to fatigue.
The Bonk
There is another risk associated with glycogen storage with pre-breakfast training. In English, it is known as The Bonk or "hitting the wall". Energy loss occurs due to the depletion of glycogen stores. Complete "Bonk" occurs when glycogen is completely depleted of muscle and liver.
The glycogen stored in the liver is depleted after a hard workout or night. Remember the fact that not only your muscles need energy, but also your brain. When you are fasting, the source of energy for the brain is glycogen in the liver. Therefore, exercising on an empty stomach runs the risk of a decrease in energy, which can cause a lack of glycogen in the muscles, but also little "fuel" delivered to the brain.
How to prevent a sudden drop in energy?
On the other hand, it is true that severe glycogen depletion occurs during longer endurance activities rather than during short and intense training. You can logically prevent a drop in energy by consuming carbohydrates and replenishing glycogen stores, especially after a long workout lasting an hour or more. An important fact is that chronic malnutrition may also be behind glycogen depletion. Therefore, if you are considering exercising on an empty stomach, keep in mind your "glycosts", which you can really feel exhausted. So it depends on the intensity and type of training you prefer.
If you are fasting despite the disadvantages of exercise, allow at least two tips:
Do not train only on an empty stomach - this method of exercise is only suitable if it is low in intensity. It is therefore not recommended to exercise more than twice a week before breakfast. So if you exercise at least four times a week, try to balance it. Leave your stomach empty for less demanding workouts, and you should replenish your energy from the diet before the intense ones.
Think about proteins and carbohydrates after training - exercise puts the body under stress and it needs nutrients for the body to regenerate after training. Therefore, give him not only carbohydrates but also proteins after training.
What to eat before training?
The aim of the article is not to convince you of a diet before exercise, but rather to point out its advantages and disadvantages. You know your body best and what works best for it. Do you prefer food to training or have you decided to combine it? In this chapter we will try to recommend what and when to eat before exercise, but also after training.
Eating something before going to the gym has several advantages:
This will increase the strength and intensity of your training
You will support the regeneration of the body
You will ensure a longer and more pleasant exercise
Your pre-workout meal should primarily provide energy for exercise, while not straining your stomach. If you are going to exercise for an hour, choose an easily digestible snack rich mainly in carbohydrates.
For the best exercise results, it is advisable to consume a meal containing carbohydrates, proteins and fats, but you have to give your digestion more time for that - about 2-3 hours. Have you ever noticed that your stomach needed a little more time after coming to the gym?
For a better overview and selection of the right food, we offer you several examples according to the time before training:
If you have an hour or less to exercise - fruit, protein bar or Greek yogurt with fruit
If you have 2 hours to exercise - protein drink, oatmeal, whole grain cereals with milk
If you have 2-3 hours to exercise - dietary source of protein with brown rice and roasted vegetables, wholemeal sandwich with protein and salad, omelette with wholemeal toast
The best way to support your performance during training is with a balanced diet. When compiling your diet, you should focus on:
meat, egg and dairy proteins,
healthy carbohydrates from fruits, vegetables, legumes and whole grains,
healthy fats from coconut or olive oil or ghi,
various nutrient-rich nuts and seeds, such as almonds,
nutritious and unprocessed foods.
Exercising on an empty stomach can be beneficial, but according to research, probably not the same for everyone. In the article, we have provided you with his "pros and cons", as well as the results of research that has addressed this topic. The most important thing is that your training suits you and does not cause health problems or slow down your fitness goals. Whether you decide to eat something or not before exercise, we believe that we have broadened your horizons again.
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