viewcount 130share

Cardio : Fed or Fasted

Praveen Budhrani
Praveen Budhrani
Back again with everybody’s favorite topic “CARDIO”, people seem to love cardio, overrate it to some extent and have lots and lots of confusions on it.
In this article, I am going to talk about whether doing fasted cardio makes us a more of a  “FAT BURNING MACHINE” vis-à-vis fed cardio. The concept of fasted cardio being superior to fed cardio is very popular among fitness followers and same has also been recommended by various popular fitness youtubers and even elite bodybuilders.
Theory of fasted cardio being superior, was first touched upon in 1976 by Ahloborg and Felig, study highlighted that consuming carbohydrate during or before the cardio session, utilized more carbohydrate than stored body fat, as fuel source in that cardio session. So it would be wiser to have fasted cardio session to burn more stored body fat.
Further, after 20 years or so, theory was further strengthened in 1997 study by Horowitz and team, stating that “small elevations in plasma insulin before exercise suppressed lipolysis during exercise, to the point at which it equaled and appeared to limit fat oxidation”.
While both the above studies are good enough to convince us that fasted cardio does helps us burn more fat during the session but burning more fat during the session doesn’t necessarily means burning more fat over the longer horizon. This was first highlighted by Paoli A and team in 2011, concluding that “If you burn more of one substrate (Fat/Carbs) during a cardio session, you will burn less of that substrate over the next 24 hours”.  In this study, fed group was burning more fat free mass as compared to the fasted group, post completion of cardio session over the period of 24 hours.
The biggest possible limitation of all above study was that they were acute studies and not performed over a longer period, to see changes in body weight or body composition.
To rescue us from our mounting debate of fasted vs. fed cardio, came the very popular Brad Schoenfeld in 2014, where 20 heathy women were randomly divided into two group performing fed cardio vs fasted cardio, who were to perform 1 hours of cardio, 3 times a week being on same calorie deficit and macro nutrient distribution for a period of 4 weeks. Both the group lost a significant amount of fat, but they found no difference between the fed group and fasted group, implying that both the type of cardio is equally effective.
Practical takeaway: While all said and done, the above studies will always be more of a hypothesis than facts, with their fair share of limitation. So, to conclude you can do fasted cardio/ workout, if you want to but expecting that to work without following overall calorie deficit might disappoint you.

I personally do fasted workout, not because I expect more fat loss but because I don’t have time to eat early morning and my appetite tends to be lower in the morning.

cheers 

New Research
https://www.ncbi.nlm.nih.gov/pubmed/25429252
Acute Studies
https://www.ncbi.nlm.nih.gov/pubmed/21411835
https://www.ncbi.nlm.nih.gov/pubmed/993155
https://www.ncbi.nlm.nih.gov/pubmed/9357807