I’m often asked whether mornings of fasted cardio are the best way to burn fat. My answer is yes … and no. When it comes to the physiology and biochemistry of the human body, nothing is simple. Throw exercise on top of normal daily functions, and things become even more complicated. So what do the experts say?

Some research does actually show that when you do cardio fasted in the morning, you burn up to 20 percent more fat. A recent study from the UK published in the “British Journal of Nutrition” found that when subjects were fasted during morning cardio they burned 20 percent more fat than when they had a meal beforehand. Several earlier studies show similar results.

Fasted cardio in the morning is effective because as you sleep and fast overnight your body conserves its precious carb stores and leans toward mobilizing fat for fuel. The story doesn’t end here, however. Your body also breaks down amino acids into glucose overnight, so fasted morning cardio mobilizes more fat and potentially more amino acids for fuel, which isn’t ideal if building muscle is your primary goal. This isn’t a huge problem as long as you consume a fast-digesting protein like whey, along with some slow-digesting casein, after your cardio.

Does fasted running affect performance?

Running positively influences the level of physical performance, although it all depends on several factors. First of all the type of training, distance and intensity. If it is short and intense, the benefits will be small.

Fasting training is generally not recommended for people who have started running. This type of activity requires prior preparation and proper progression. Otherwise, there is the possibility of nausea, dizziness, vomiting and, if the body suffers from low blood glucose levels, even loss of consciousness.

The main objective of running on an empty stomach is that the body has to resort to the use of fat to have a minimum level of stored carbohydrates. And it is that carbohydrate reserves last about 3 hours in the body, while those of fats are unlimited.

This type of training is more effective in the competition world. Experienced runners try to increase their performance in long runs by working at a low to medium intensity level. The idea is that the body adapts to the new situation and prevents unnecessary risks.

Recommendations for running on an empty stomach

If in the end you have encouraged to run on an empty stomach, it is advisable to follow a series of guidelines or tips to do it correctly:

-Everything depends on the physical level of each person, although it is preferable that a race on an empty stomach does not exceed 60 minutes.

-It is important to run at a low intensity, enough to be able to carry on a conversation.

-Before going out, it is advisable to be well hydrated and drink a glass of water before going out.

-In the beginning, it is better not to run after 8 hours without eating and start with a fast of about 4 hours.

-It is advisable to carry something to eat to take a break as soon as a feeling of dizziness occurs.

-After finishing the training, spend some time with the first meal of the day. Add protein and carbohydrates and hydrate well to improve muscle recovery.

The 3 myths of running on an empty stomach

For many people, running on an empty stomach is part of their regular training, while for others it is unthinkable. The truth is that everything depends on the level of intensity and the objective pursued. Be that as it may, these are some of the most popular fasting running myths you should know:

1. Training on an empty stomach is equivalent to losing muscle mass. It is not entirely true. When you go for a run in the morning, your body uses up its remaining glycogen stores and then turns to free fatty acids. If the runner increases the intensity of his training, he will draw energy from proteins, something with which he can lose muscle mass. However, most runners do not reach that point.

2. Train on an empty stomach to lose weight. It is true that, when running on an empty stomach, the body can pull in fatty acids for energy. However, given the low intensity of training, the consumption of energy expenditure is lower. Thus, when losing weight, it is preferable to opt for higher intensity running sessions in which more calories are burned.

3. Running on an empty stomach increases endurance. The lack of glycogen makes the duration and intensity of the training shorter, so it is preferable to bet on a training with greater stimulus to improve performance.