The generalized understanding by us all is that if you do fasted cardio it can increase the fat oxidation period; thus, an increase in fat burning will be the result. By this understanding, doesn’t fasted cardio sound pretty good? To be honest with you all, from my research, there is unfortunately a lack of evidence to tell us whether fasted or non-fasted cardio is better than the other. I think this is more of a personal preference. I also think that fasted cardio goes very well with someone that routinely performs intermittent fasting. For me, I simply enjoy doing fasted cardio first thing in the morning after my coffee. Then I would shower, go downstairs, make my breakfast, and be satisfied with how I felt when I looked in the mirror. This is what motivated me to do my cardio every single morning six days a week because I was seeing results physically, mentally, and I was happy with what I was looking at in the mirror. In the end, isn’t this why we do physical activity? To feel good and look good in order to do well in life!
The other way to look at fasted cardio is that it can help you follow more of a caloric deficit diet with the result that weight loss would be seen. For example, depending how long you fast for, you’re eating period may be shaved down to perhaps an eight-hour window versus a twelve-hour window depending on your personal routine, life, and work schedule. This would be something more of following a 16:8 intermittent fasting schedule, which we had previously discussed in prior blogs. Meaning you fast for sixteen hours and eat during the eight-hour window. So, the fasting period begins after your last meal the night before. For example, you eat at 8pm and don’t eat again until noon the next day. Even if you are not doing intermittent fasting you are still taking that thirty to forty-five minutes in the morning to do cardio rather than eating first thing. It is still eliminating a small window of your eating period. I stumbled upon a handful of systematic reviews and meta-analysis from 2017 which discovered minimal changes amongst body composition following aerobic exercising in the fasted and non-fasted state (Hackett and Hagstrom 2017).
If you think back to the previous post, we discussed through keto and intermittent fasting there is limited glycogen to be used for your workouts. Thus, your body will utilize fat as your fuel during this fasting period. Again, depending if you continuously practice some form of intermittent fasting your body is most likely tapping into fat storage. Due to the fact that your blood glucose and insulin levels remain low during this fasting window. Particularly more than a twelve-hour window of fasting you will have this fat oxidized.
We could go back and forth to discuss various studies; however, there are not enough reliable resources out there to state, “Yes fasted cardio is better because…” What I can tell you is that if fasted cardio makes you feel better, look better, and start your day off right then I would say do fasted cardio. If you do not like fast cardio, then that is fine. This journey is all about you finding what works for you, fits your lifestyle, and helps you reach your goals. First thing in the morning for me is a must with cardio because it starts my day off right physically and mentally so that is what I will stick with doing. Once my knee recovers and allows me to get back to fasted cardio! LOL.
Hackett, D., and Hagstrom, A. D. 2017. “Effect of Overnight Fasted Exercise on Weight Loss
and Body Composition: A Systematic Review and Meta-Analysis.” Journal of Functional
Morphology Kinesiology, November 25. https://doi.org/10.3390/jfmk2040043.