If you have been training for a while it is probable that you have heard of the concept of doing your cardio workout first thing in the morning before having anything to eat. By following this method you are ensured to burn more fat than you would when you train after eating.
This method of training was introduced in 1999 by sports training expert Bill Phillips, who indicated that working out on an empty stomach helps in burning more fat. This has made a lot of people rush to the treadmill before having a single bite.
Phillips supported his idea by a well known biological fact that after fasting for extended number of hours the circulation of sugar in the blood will be very low which leads to an extreme low level of glycogen (stored as carbohydrates). With the absence of glycogen the body does not have any source for energy and thus starts using fat for fuel.
In addition to that, the low levels of insulin, due to fasting, promotes the generation of fatty acids that will also be used as fuel to do the exercise.
This strategy was very popular in those days; after all who does not want to burn more fat and get leaner with the same amount of work?
Unfortunately the bad news is that this method does not work for the following reasons:
1. It does not give a deep thought about metabolism and how it works. The body's metabolism establishes a kind of equilibrium when burning fat and other substances in the body. When you burn more fat during exercise you will burn more carbohydrates afterwards, and vice versa. So who cares if fat burning is maximized during exercise if this will be switched over after the workout.
This is a shortsightedness of this program. When somebody wants to gauge the metabolism effect he should measure the long term effect, i.e. in days and not hour to hour.
2. Another thought about the breakdown of fatty acids. It is true that the breaking of fatty acids will be more when you do your cardio on an empty stomach but the rate of this breakdown is more than what you consume while working out. This leaves a number of fatty acids floating around in the blood system that will not be utilized in your workout.
These floating fatty acids will form again in the form of triglycerides which will again be deposited in the body leading again to the same results where you started, more fat cells.
3. The benefits of fasting cardiovascular training will have effect only on low intensity training and after training for extended time. Experiments were made where subjects were trained for 50% of their maximum heart rates, which corresponds the intensity of regular walking. These subjects did not burn more fat than those who trained after eating. The results started to shift in the favor of the fasting team only after 90 minutes of training leaving us wondering who will be able to train with no food for a couple of hours.
4. Fasting cardiovascular training does not take into consideration the excess post-exercise oxygen consumption (EPOC), or what publicly known as the after burn. This EPOC represents the calories that are burnt after finishing the workout. Studies have shown that this after burn is promoted further if a person eats before training. These calories burnt to produce energy come from fat.
5. Studies have shown that high intensity interval training (HIIT) does wonder in terms of calories burnt from fat. This high intensity is impossible to achieve when you are fasting. The body needs a good supply of glycogen to provide it with the energy needed to perform these HIIT.
6. Training when you do not have a good level of glycogen is catabolic in nature. Meaning you will be burning more of your muscle tissues. When you train on an empty stomach you tend to lose 10% of your total calories from protein, this is double what you would lose when you train after having a pre workout meal.
As a conclusion, doing your cardio exercises on an empty stomach does not have any advantages; in fact it might have negative effects especially for those who want to build muscles. This form of training will end up in making you lose muscle and decrease your fat loss.
I bet that you have a question in your mind now and that is 'what should I eat?' This will vary depending on the duration of the exercise and its intensity as well as when did you have your last meal, additionally there is the genetic factor.
As a rule of thumb, to provide your body with amply supply of energy and to prevent any muscle shrinkage you need to consume ¼ gram of carbohydrates and 1/8 gram of protein for every pound of your body weight. So, if your weight is 200 pounds you should consume 50 grams of carbohydrates and 25 grams of protein.
Training on an empty stomach is an old theory that has been challenged by many physical training specialists, since this theory was out to the public many studies has been made to contradict it. Having a nutritional pre workout meal that is rich in carbohydrates and proteins is essential for your fat loss and muscle building efforts.