Training on an empty stomach: will they help to lose weight faster?

We tell how the training on an empty stomach affects the body.

The theory of an increased level of fat burning in fasting training has become especially popular after the publication of the book by American writer and entrepreneur Bill Phillips “Body for Life”. This training strategy is explained by the fact that in the morning, before the first meal, we have a lower level of glycogen – in this form the body stores carbohydrates in muscles and liver for energy supply. This is such a tactical reserve, with a deficit of which the body chooses an alternative source – fats. It is logical to assume that this way you will lose weight faster. Sounds reasonable. We are sorting out whether this is so.


When and how we spend fats

Always. The most important thing to understand and accept – the body can not completely turn off one source of energy and start another. There is no way to run so as to spend only fats, or squat only due to carbohydrates. There is no such thing that we run and spend only fats or do sit-ups exclusively at the expense of carbohydrates. We spend and stored carbohydrates, and fats, just in different proportions, in which – the body decides.

Briefly on the physiology of fat burning:

  • Fats in the body are stored in the form of triglycerides in special cells – adipocytes.
  • Mobilization (lipolysis) occurs due to special enzymes – lipase. They break down triglycerides to glycerin and fatty acids that go into the bloodstream.
  • Further – the oxidation of what came into the blood, followed by the production of an ATP – molecule, which we use as an energy source.

Why everything is not as we want

Studies conducted in 2011 and 2014 showed how the body reacts to fasting exercises, whether it can use an increased level of fatty acids to generate energy and whether the use of carbohydrates interferes with the fat burning process.


1. In 2011, two experiments were conducted , in which people practiced cycling for 80-120 minutes. The results showed:

– The intake of carbohydrates before or during exercise does not prevent the use of fats as an energy source .

– The participants who trained on an empty stomach, the mobilization (lipolysis) of fatty acids did occur faster and in greater volume. But they did not oxidize – that is, the body did not use more free fatty acids to generate energy. Accordingly, all unnecessary returned to their seats.

2. Three years later, in 2014, JISSN (The Journal of the International Society for Sports Nutrition) published the result of a study in which participants performed cardiovascular work for a whole month for an hour with moderate intensity 3 times in Week.

A total of 20 people were divided into 2 groups: 10 people trained in the morning on an empty stomach, the rest – after eating.

Both groups were fed the same day, the calorie deficit in the diet was 500 kcal.

Result: for all participants, changes in the body composition were the same regardless of whether they were trained after eating or on an empty stomach.

3. It is incorrect to consider the fat burning process only during training. We have a complex organism that constantly adapts to changing living conditions and regulates the proportion of the use of fats and carbohydrates as sources of energy.

4. A rational way is to observe the training process and nutrition in a complex and for a long time.

In an ideal – to make bioimpedance analysis of the body, and at least twice with an interval of several months. This is a study that shows the composition of the body: the amount of fat tissue, the basic metabolism, muscle mass, weight (norm, deviation), etc. The service can be used, for example, in fitness clubs. If repeated analysis shows that nothing changes, it is worth, for example, to adjust the training format (mode, intensity, type) and nutrition.


Possible consequences of training on an empty stomach

  • Any training on an empty stomach can cause bad health : nausea, loss of consciousness, and in the worst case – hypoglycemia and hypoglycemic to whom because of the low glucose content in the blood. If you prefer to train in the morning, but can not or do not have time to eat before training, take with you a little sweet water – this will protect you from unpleasant situations.
  • The American Fitness Organization (ACE) notes that in the morning, because of a deficiency of glycogen in the body. The concentration of the hormone cortisol, an important substance. It is one of the functions of which is the control of a certain level of glucose in the blood. With prolonged training or exercise on an empty stomach, his task is to make sure that we do not get sick and the brain continues to work. Cortisol is actively involved in the work with a deficiency of sugar in the blood. It participates in gluconeogenesis – the process of glucose formation from non-carbohydrate compounds. The source for this can serve as proteins that are contained in muscle tissue. Consequently, its direct function – construction – the proteins will not be able to perform. That is, if the goal is to increase muscle mass. Then it is reasonable to eat before the start of training.
  • An increased concentration of cortisol, or a stress hormone, as it is commonly called. It can also affect fat deposition in the abdomen. And since during training on an empty stomach the fatty acid content in the blood rises. Not all of which are ultimately used for energy.  Cortisol promotes their deposition directly into the abdomen .


According to existing studies, the only thing that will help to lose weight and keep fit. It’s balanced nutrition and regular training.


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