Sport on an empty stomach, benefits, and dangers, you need to know Running on an empty stomach.
Doing cardio on an empty stomach would burn fat more effectively, but beware of health risks.
On an empty stomach, our body is much more willing to consume fats in the absence of sugars immediately available in the blood. An interesting phenomenon a priori to more easily lose a few extra pounds. This recognized practice is not, however, without risks. Practicing sport on an empty stomach requires a few warnings and precautions to avoid boredom: explanations and advice.
More fat burned on an empty stomach Fuel for muscles. Our muscles use carbohydrates for fuel to function. This energy comes mainly from Sugars from food and supplied by the blood after a meal; Glycogen stores available in muscles and liver;
Degradation of fatty acids or lipids, in other words, fats. This process is slow, and alone is not enough to provide intense effort. The lower the effort's intensity, the higher the percentage of fat consumed (see our article on How to burn excess fat effectively). Lipid degradation increases markedly after a few minutes of activity. After a meal, a large part of the muscles' energy comes from carbohydrates produced by digestion and carried by the blood. This energy supply replaces the glycogen reserves and also significantly slows down the process of lipid degradation.
This is where the interest in the sport on an empty stomach comes in. After a night's sleep, the liver's reserves, used to maintain a constant blood sugar level and supply energy to our organs, including the brain, are weakened. The practice of physical activity in these conditions causes the body to draw more on fats, in particular, to maintain the blood sugar level. We will consume as much energy in the end, but the amount of fat burned will be greater in proportion.
This theory is confirmed by several studies, including one conducted at Kansas State University in 1995 on young and physically fit individuals.
The study concludes that, for the same activity, fat is burned more quickly by exercising in the morning on an empty stomach than after a meal, even if the same amount of energy is expended in both cases. The percentage of fat burned is higher on an empty stomach, reaching 67% against only 50% after eating. (Source: Wilcox, Harford & Wedel Medicine & Science in Sports and Exercise, 17: 2, 1985)
Benefits of training on an empty stomach A priori, training on an empty stomach has two main advantages:
Optimizing the process of fat degradation (lipolysis) makes it possible to lose weight more easily, an asset both for health and aesthetics and for improving performance. It accustoms and trains the body to be more efficient in mobilizing fats, i.e., their transformation into energy usable by the muscle. This point is particularly interesting in long-term endurance sports such as cycling or the marathon, which deplete glycogen reserves in a few hours.
If the value of training on an empty stomach is scientifically proven, it can be dangerous. It is important to understand the mechanisms involved and respect certain rules to fully and safely benefit from this practice. Warnings.
Training on an empty stomach is strongly discouraged for people who do not regularly practice endurance sport or resume activity after a prolonged stoppage and people with poor health. In any case, you should seek the advice of your doctor.
Limited liver reserves Carbohydrates are essential for our body to maintain its vital functions and ensure daily physical and intellectual tasks. The sugars stored in the muscles in the form of glycogen can only be used locally by the muscle. Our organs, including the brain, are supplied with blood glucose maintained at a constant liver rate.
Therefore, the liver plays an essential role in maintaining a constant blood sugar level from its own glycogen reserves: the hepatic reserves. This intake is particularly important for our brain, which alone consumes 4 to 5 grams of carbohydrates, or the equivalent of a piece of sugar, per hour. After a night's sleep or a fast, the liver's reserves (60 to 100 g maximum) are weakened or even exhausted. This has several consequences that must be known to understand them better .###
Watch out for hypoglycemia! By going to a sport on an empty stomach, one is exposed to a hypoglycemia or “craving” attack due to weakened liver reserves. Just as a car cannot start without a battery (the liver) despite a full tank of fuel (muscle reserves), when blood sugar levels drop below a certain limit, the brain protects itself by idling, forcing the premature cessation of activity.
Barriers, dizziness, or discomfort can end the outing. Watch out for muscle wasting! When glucose is lacking, our body, to ensure the brain's functioning, manufactures it from amino acids, the basic building blocks of proteins. Thus, it nibbles everything that contains it: liver, kidneys, skin ... and muscles. Practicing sport on an empty stomach in poor conditions can cause muscle wasting harmful to health and irreversible after 25 years. This is the reason why low carbohydrate diets can be ineffective or even dangerous.
Fatigue, lack of energy, headaches By forcing the body to work harder to maintain vital functions, training on an empty stomach can lead to a state of exhaustion. It can be responsible for various disorders: headaches, lack of energy, depression, constipation, diarrhea, etc.
Toxic waste alert In the absence of glucose, the nerve cells can be satisfied with replacement energy, the ketone bodies. These are produced by the breakdown of fatty acids (lipids). When produced in too much quantity, ketones accumulate in the blood and become toxic waste to the body, causing kidney problems and poor recovery. In extreme cases, ketones cause a coma and can be fatal.
Storage or destocking? The body gets used to deprivation and excess very well, adapting its metabolism accordingly (see our article on how to increase your metabolism and burn more fat ). By depriving it, we encourage it to store more fat during the next meals. It is, therefore, important not to overdo training on an empty stomach.
By practicing the sport on an empty stomach, the body is forced to draw on its fat reserves by the process known as "lipolysis." But this degradation process requires a minimum of sugars to function ?? Playing a sport on an empty stomach can therefore slow it down.
In practice: what to do and what not to do.
Before the effort, prepare well. Eat high glycemic index carbohydrates (wholemeal pasta, rice, whole starchy foods) the day before your outing to replenish muscle glycogen stores and ensure sufficient energy for your morning activity. Don't jump out of bed! Allow at least half an hour to give your body time to wake up.
Hydrate yourself! Drink water the day before, upon waking up, and at least 10 minutes before exercise. A full glass of water when you get up will wake up your body and your metabolism. Eat a light carbohydrate breakfast; this will give you the few sugars you need to prevent hypoglycemia and muscle wasting without negating the benefits of training on an empty stomach. Wake up numb muscles with a proper warm-up. If you go for a run on an empty stomach, don't start with a sprint! During the effort. Some basic rules. Train on an empty stomach a maximum of 2 times a week for a maximum of 1 hour per session. Beyond that, you expose yourself to the health problems described above (fatigue, depression, particularly).
Choose a loop route or close to shops to enter more easily or to refuel in case of failure. If you go for a run on an empty stomach, equip yourself with a banana belt to carry a drink and energy bars.########## Go quietly and maintain a moderate pace throughout the course. Your heart rate should stay between 60% and 70% of your maximum heart rate (HRmax). Stay hydrated during exercise. Water is essential for exercise and necessary to ensure the breakdown of fat (see our article on the importance of good hydration ). To avoid hypoglycemia, we strongly recommend that you consume an isotonic drink.
Always take some energy bars with you, useful in case of failure. We advise you always to consume a little sugar during exercise, whether in solid or liquid form, to prevent the risks described above. After the effort, comfort.
The practice of stretching after a shower and possibly a muscle massage or electrotherapy. Stretching helps muscles relax and regain their original length. They restore elasticity to muscles and tendons and mobility to joints. They keep you flexible. Don't skip breakfast after your outing. It is essential for your recovery. Eat foods providing the nutrients you need, especially those degraded during exercise, i.e., proteins (yogurt, fish, eggs, ham, poultry, cheese), trace elements ( magnesium, iron, zinc, etc.), and vitamins (whole grains, fresh fruits) and essential fatty acids (vegetable oils, oleaginous fruits).