Fasting Cardio: Burn Fat or Muscle?

Cardio workouts performed on an empty stomach are a great way to get rid of body fat. However, given that they are performed on an empty stomach, not only fat is lost, but also muscle tissue . To engage in such training, you need to weigh the pros and cons of this approach to burning fat.

Cardio training plays a significant role in fat burning. Fat becomes an energy source after the depletion of glycogen, which occurs as a result of prolonged cardiac workloads, when the pulse rate reaches 60-70% of the maximum. Based on this feature of training, it is logical to assume that cardio without breakfast, that is, on an empty stomach, can accelerate the burning of subcutaneous fat.


  • 1 Efficiency of “hungry” cardio
  • 2 Fasting Cardio as part of a workout program
  • 3 Breakfast or not after cardio on an empty stomach
  • 4 video review

The Effectiveness of “Fasting” Cardio

There is no unequivocal opinion on how effective morning cardio exercises performed on an empty stomach exist. Disputes on this topic have been ongoing for a long time. Both supporters and opponents cite the results of scientific research, the biological processes and mechanisms in the human body, as the evidence base for their innocence. Researches of scientists also demonstrate conflicting conclusions. To come to a decision, you should get to know more about how energy expenditures occur during training.

The source of energy spent during anaerobic and aerobic exercise are the carbohydrates accumulated in the body, i.e. glycogen. This happens until its stocks come to an end. In the morning, its level is minimal. If a person does not have breakfast, protein catabolism begins to occur. Fasting proponents cite this fact as an argument that instead of carbohydrates, fats are used in the morning workout.

However, one should not forget that with the reserve energy reserve, which is fat, the body begins to "part" in the last turn. And even if glycogen is at zero, some time it will be spent not in the fat layer, but in proteins - muscle tissue. Consequently, when performing cardiotraining on an empty stomach, both fat and muscle are lost. This is especially important for those who do not just want to lose weight, but exercise weight, trying to find a beautiful and elastic body. People who fundamentally need to maintain muscle are advised not to exercise on an empty stomach, but to have breakfast.

Professional athletes taking part in competitions resort to fasting cardio exercises to speed up the process of fat burning. However, the concept of “fasting” for them is conditional, because they use amino acids before training. This avoids the cost of muscle protein as an alternative energy source.

Fasting Cardio as part of a workout program

Cardio without breakfast is recommended in the following cases:

  1. upon reaching a "plateau" - a reduced rate of burning body fat against the background of the body's adaptation to changes in diet and loads;
  2. after a complete overhaul and getting used to the sports program that has been used for a long time.

It is recommended to resort to "hungry" cardio on a temporary basis with certain interruptions. Regular exercises will lead to the fact that the body adapts to such a regimen. The main thing to remember is that muscle loss is inevitable, and in some cases, depending on individual characteristics, lethargy and fatigue can be observed.

Breakfast or not after cardio on an empty stomach

A common mistake practicing this type of training is a complete rejection of the morning meal. Many believe that if you do not eat before lunch, then the effect obtained from "hungry" cardio will increase. This approach is fundamentally wrong.

Lack of food in the morning serves as a signal for the body to an upcoming hunger strike. It starts the mechanism of accumulation of fat. Therefore, muscle mass is lost, and the energy received from subsequent meals is instantly deposited in the fatty layer.

Avoid this carbohydrate breakfast after cardio workout. Such a meal not only blocks the fat storage program, but also significantly reduces muscle loss. But, even taking such measures, you should not take this type of physical activity as a full-fledged training in fat burning.

To start the process of burning fat, it is not enough just to engage in cardio training, you also need to lower the amount of calories consumed. If the caloric content of the daily diet remains high, even the most intense workouts will not be able to compensate for the overabundance of energy entering the body along with food, and the result will be practically zero.

Video review