Fasted Cardio vs. Non-Fasted Cardio

[Brazensol]

Found this while doing some reading this morning:

Triathletes and marathoners must train their bodies to use fat instead of carbohydrates as fuel in long bouts of exercise, says Brendan Brazier, professional Ironman triathlete and author of "Thrive: The Vegan Nutrition Guide." When you do low-intensity exercise that lasts more than three hours, your body burns 20 percent carbohydrate, 70 percent fat and 10 percent protein. This compares to 90 percent carbohydrate, 3 percent protein and 7 percent fat with high intensity exercise lasting one hour or less. If you do moderate intensity exercise that lasts one to three hours, your body will burn 60 percent carbs, 35 percent fat and 5 percent protein, according to Brazier.

I am assuming ( I know, I know) this is how fuel conversion breaks down for non-fasted cardio. Does anyone know if this holds true with fasted cardio? I am trying to get a grip on how much lean mass I am burning because I have lost ~2 lbs of lbm over the last 3 weeks after making good gains the prior 3 months or so.

[MuscleInk]

This is a common question and there are several threads already posted around the topic. You'll find arguments favoring both sides of the issue. Personally, I subscribe to fasted cardio beliefs. I find it to be more effective in cutting fat vs. non fasted and I prefer moderate cardio 2 hours a day over HIIT - just easier on my joints which is an important factor when cutting because many of the compounds I cycle when cutting are drying agents and it cause more repetitive stress injuries. Cycling gear during a bf reduction protocol will also minimize catabolic effects of fasted cardio which is a concern for some people as well.

Of course, cardio must incorporate a proper nutrition plan for dropping bf. Many people believe 500 cals below your TDEE for your current LBM is appropriate. I usually incorporate IF with my cutting cycles and cardio.

[Brazensol]

This is a common question and there are several threads already posted around the topic. You'll find arguments favoring both sides of the issue. Personally, I subscribe to fasted cardio beliefs. I find it to be more effective in cutting fat vs. non fasted and I prefer moderate cardio 2 hours a day over HIIT - just easier on my joints which is an important factor when cutting because many of the compounds I cycle when cutting are drying agents and it cause more repetitive stress injuries. Cycling gear during a bf reduction protocol will also minimize catabolic effects of fasted cardio which is a concern for some people as well.

Of course, cardio must incorporate a proper nutrition plan for dropping bf. Many people believe 500 cals below your TDEE for your current LBM is appropriate. I usually incorporate IF with my cutting cycles and cardio.

I was mostly curious as to how much of the various fuels are burned between the two. The info in my original post is the first time (that I remember anyway) I have ever seen percentages from the various fuel sources. I am currently eating 450 calories under my TDEE and am doing a 35/40/25 macro. My diet has been 95%+ spot on with a few minor slips along the way. Just trying to figure out why the loss of lbm after making good gains (38.5# of fat dropped and 10# of lean gained). I have lost over a 1/4" on my biceps... I know some of that is fat but is all of it fat? Strength and reps continue to go up so not to worried about cutting too much. Yet. lol.

[MuscleInk]

I was mostly curious as to how much of the various fuels are burned between the two. The info in my original post is the first time (that I remember anyway) I have ever seen percentages from the various fuel sources. I am currently eating 450 calories under my TDEE and am doing a 35/40/25 macro. My diet has been 95%+ spot on with a few minor slips along the way. Just trying to figure out why the loss of lbm after making good gains (38.5# of fat dropped and 10# of lean gained). I have lost over a 1/4" on my biceps... I know some of that is fat but is all of it fat? Strength and reps continue to go up so not to worried about cutting too much. Yet. lol.

Most likely some water loss as well. I'd have to go dig through some of my med texts to see if there is any detailed discussion of burn rates across macros. Intuitively it is argued that fasted cardio is better at targeting fat due to little or no stored glycogen as a fuel source, but I've seen others argue that with HIIT cardio, non fasted exercise programs are just as effective at burning fat and some have argued that its a safer approach due to reduced catabolic events.

I'm sure one of our nutritional gurus will jump all over this shortly. I'm trying to recall the members that advocated non-fasted cardio over fasted cardio. One is a long standing member but I can't recall who.

[Brazensol]

Most likely some water loss as well. I'd have to go dig through some of my med texts to see if there is any detailed discussion of burn rates across macros. Intuitively it is argued that fasted cardio is better at targeting fat due to little or no stored glycogen as a fuel source, but I've seen others argue that with HIIT cardio, non fasted exercise programs are just as effective at burning fat and some have argued that its a safer approach due to reduced catabolic events.

I'm sure one of our nutritional gurus will jump all over this shortly. I'm trying to recall the members that advocated non-fasted cardio over fasted cardio. One is a long standing member but I can't recall who.

That is exactly my concern since I've been doing fasted cardio for 3 weeks now (since June 6th) and it's oover this period that I've noticed a decrease in lbm. I think it is more than coincidence but not 100% sure. It may just be that fasted cardio is not for me.

[spin_doctor]

I have done it both ways over the years. Some not by my choice in the military. They have their own mindset on this. I personally prefer to wake and hit cardio without eating anything. I like low intensity long workouts as I am more a distance runner. Until somewhat recently that worked well for me. Nothing against HIIT, just personal preference.

[Brazensol]

I wasn't sure how I'd feel about doing fasted cardio. My first thought was I wouldn't like doing it on a totally empty stomach but after doing it for a month now I think I prefer it.