In the fitness world, well mainstream one, cardio is sold as the best way to lose fat, burn fat and lean up. Let me start out by saying that is not true. Resistance training is the best way to burn fat, lose weight and lean up. Additionally, nutrition as a compliment. So where does cardio fit in? Although there are numerous forms of cardio I can cover for this blog's purpose we are going to be defining what is considered "fasted cardio" and whether or not it measures up to the hype!
Fasted cardio is when you are performing cardiovascular activity without food in your system, since it followed a long fasting period. Fasted cardio has become very popular in the physique industry but what exactly is it, who should do it, and does it even work!?!?!
When you are asleep your body goes without food for a prolonged period of time, which is inherently “fasting.” Your insulin, glycogen and blood sugar will reduce as a result of this fast.
The purpose of fasted cardio is to train in a condition when you are in a lowered sate of insulin / blood sugar / glycogen.
In theory, your body will adapt to using fat as the predominate energy source.
Low levels of insulin mean fatty acids are moving around powering the body. Engaging in exercise during this time means that you will use more stored fat to power the workout, which encourages the body to do this for longer bouts at a time. Researchers at the Department of Kinesiology in Samford University studied 12 female NCAA Division I athletes, each of whom completed two workouts. One resistance workout session happened after a 10-hour fast, while another happened after a fat- and carb-loaded meal. Following the two workouts, the researchers found that the fasted session allowed the body to use more fat as energy than carbohydrates.
Two styles of fasted cardio that I select from are Fasted and Protein Fed… protein fed is when you only have protein prior to your early morning workout. Protein fed is a great option for those looking to stay lean but not burn off a ton of muscle.
Although it is highly effective not all men and women need to engage in this activity. Here are a few ways I prescribe this activity and for whom…
Heavily Overweight… I would recommend performing 20-30 minutes of fasted cardio 3 days per week. 1-2 of those can be lifting weights in a circuit format while the other 1-2 should be interval cardio training. Additionally, I’d recommend performing resistance training 3 days per week for about 45-60 minutes fasted as well.
Burn Fat… if your goal is to burn fat, but not necessarily lose a ton of weight then I’d suggest doing 3 days per week at 20-25 minutes of interval cardio training. Additionally, 4-5 days of the week engage in resistance training for 60-75 minutes. If you do your resistance training in the morning do it protein fed but not fully fasted.
Build Muscle and Burn Fat… do fasted cardio 1-2 days per week for 15-20 minutes. Additionally, you can engage in protein-fed resistance training 5-6 days per week.
Fasted cardio or protein fed cardio are both highly effective for similar reasons. Either way, early morning training is a great way to lose weight, burn fat and lean out!
1. Frawley K, Greenwald G, Rogers RR, Petrella JK, Marshall MR. Effects of prior fasting on fat oxidation during resistance exercise. Int J Exerc Sci. 2018;11(2):827-833.