Fasted cardio methods have been in the bodybuilding and physique competitors circles for years. The theory is: if your body is low on glycogen, you will be more apt to burn fat as fuel. The theory seems logical. If the goal is to burn body fat you don’t want to have a lot of glycogen to burn, especially useful when dieting. There is also a psychological benefit to this as well. If you feel less “full” from having an empty stomach, hunger becomes high. This can be associated with a more lean or skinny stomach type of feel, but there is not the science behind this, just anecdotal evidence.
It is popular and believed to be true. This is because if you add dieting, hard training, and couple that with fasted cardio, you will lose body fat. The thing is, the fat loss may not be from the fasted cardio. Fat loss is typically happening from intense dieting and dialing in the training regimen.
Most science will show that there is not a much significant difference in fasted and non fasted cardio groups when diets and training protocols are similar to this study HERE.
This study also concludes that when performing moderate intensity endurance when fasted does not increase lipid utilization.
So does it work?
It’s debatable. Most “evidence” comes from bro science and anecdotal evidence says it is possible.
I personally feel that fasted cardio will not make or break your fat loss efforts. It can help in a way, however. If you simply don’t consume food during set periods of the day, you have a smaller window to consume calories. So by cutting calories around your workout, you are simply cutting calories, which can work for fat loss.
If you cut too many calories and amino acids during dieting phase you do run the risk of possibly losing muscle mass. Losing muscle mass can hinder fat loss in the long run.
So, I feel that taking in 5-10 grams of BCAA or EAA with 3-5 grams of creatine or maybe just a scoop or two of quality whey is the best option. It limits calories but provides a buffer between meals to make sure muscle mass is not lost and blood sugar levels are sustained for optimal energy and performance.