Cardio can be effective whether it is done while you in a fasted state or not. However, research shows that if your goal is fat loss then the best time to do cardio is in a fasted state (before breakfast or at least 4 hours after a meal.) I personally do cardio 3-4 times a week every morning after my workout when my muscle glycogen reserves have been depleted and fat is the only source left to be consumed by the body for energy. Doing too excessive amounts of cardio could also cause the body to begin to tap into amino acids as fuel if you push it too far,; turning cardio into a catabolic, muscle-wasting activity.
Although cardio is always considered catabolic and not anabolic, what really matters is what is fuel source is being used: fat, glucose, or muscle? That is why I highly suggest that if one trains in a fasted state to consume amino acids to avoid muscle-wasting during this period of time.
As to how much cardio is needed, it doesn’t take hours upon hours of intense, heart-throbbing and painful sessions to lose fat as most people may imagine in their minds. Most of your fat-loss will be achieved by following an effective diet where you burn more calories than you consume daily over time. In other words, you do not have to kill yourself doing extremely intense, muscle-wasting cardio thinking that is the only way to lose fat. Cardio should only be used as a tool to speed up this process and assist with your fat loss goals.
There are two kinds of cardio one can partake in to help speed their metabolism to reach their goals quicker:
- Light Intensity Steady State cardio (LISS) is a perfect example of this is a one-hour walk on the treadmill or outside at 3.5 mph a few days a week. Doing this while following a healthy diet, can totally help transform your body over time – the key is remaining consistent with your diet and cardio and the results will come.
- High Intensity Interval Training (HIIT) if you don’t have much time to spare you can do intense cardio for a short period of time to raise your metabolism quickly to burn off fat as well. Doing a 25-30 min cardio session of sprinting one min, then walking 2 mins, and repeating, or doing sets of jump rope, are two an examples of this. The key here is to not do this too long otherwise you will start breaking down muscle as energy and this kind of cardio become detrimental to your goals.
Even though your goal is to lose fat, sparing muscle should also be of top priority as well. Muscle takes a lot calories to be maintained, thus it helps burn fat by using more calories. In other words, the more muscle you have the more fat you will burn at a resting state because you have more lean tissue to maintain than not. So whether you choose to do LISS or HITT cardio make sure you are not wasting your muscle away because then you will have a harder time losing fat.
Whether you do cardio in a fasted or fed state, at the end of the day the calories burned will essentially be the same, but the difference between the two is where your body will get its energy from. If you do your cardio in a fasted state the body will break down stored fats in order to fuel the work out. In this situation, your insulin level is low and will not interfere with lipolysis (fat burning process), thus allowing you to access and burn more stored body fat for fuel. When you eat and then train within the four-hour window (before you are considered fasted), the body will have already converted foods into glucose (sugar) which increases your insulin levels, which then in turn suppresses lipolysis. The reason for this is because lipolysis actually takes longer to initiate than glucosis (process of turning foods into sugar for fuel) so the body will use the glucose instead of your stored fats because it is the fastest way to get energy to satisfy workload demands since it is readily available.
Research has also shown that fasted cardio increases the efficiency of lipolysis by 20% more compared to doing cardio in a fed state. Although in both cases one’s metabolic rate will be revved up for the next 24 hours, and fat loss will occur that day regardless, more stored fat will be burned when doing cardio in a fasted state. Even though there is really only a small difference, say, 120 calories (13 grams) of fat burned off per day when doing fasted cardio, these losses will eventually add up to almost a pound of pure fat burned off in a month. If you stick to this simple yet effective method, pounds of fat will be melted off in the following months simply because you chose to do your cardio at the more efficient time possible.
The human body prefers to take the path of least resistance because it wants to conserve energy and maintain homeostasis (regulation and balance of its functions). It hates when things change; that is why when it come to changing your body; such as building muscle or losing fat, one has to force the body to change; which is why getting results takes time, patience, and perseverance, and why most people fail to stay the course and achieve the body they want.
Just by changing by implementing this simple yet powerful knowledge into your cardio routine and sticking to it for months. Try it out and see for yourself. You have nothing to lose but your unwanted body fat.