dhelsel1 - it looks like I lost 6 lbs total throughout the fast then gained back 3 lbs of water/glycogen/etc. I did workout during the fast so I had to have been using some bodyfat for fuel

But I am below my stalled range which I like and appear to be losing again, but we'll see in a week or two.

I chose three days because I wanted to end the fast at home rather than on a work day.

Quite true fattyman007. But with my glycogen stores already low and the fact I was doing HIIT and weights, I think I'm confident I lost some adipose tissue.

Do you read Peter Attia at The Eating Academy? He has some interesting writing and often talks about CO2 ratio, VOx, etc.

Why is it important? What if I did 45 min of low intensity cardio? HIIT? Only weights? An hour of house work? If you have a general goal to lose fat (ie not training for a marathon), there might be a small difference in fat loss vs glycogen used, but if I continue to fast after my exercise, how different can they be? What am I not seeing?

I believe HIIT gives better results for less time compared to low intensity aerobic and I do weights for insulin resistance help.

You typed a lot but didn't answer my question. You said "Its important for any one on low carb diets to understand what happens in high intensity workouts.".

I asked "Why is it important? What if I did 45 min of low intensity cardio? HIIT? Only weights? An hour of house work? If you have a general goal to lose fat (ie not training for a marathon), there might be a small difference in fat loss vs glycogen used, but if I continue to fast after my exercise, how different can they be?"

So again, what is important? Is one not effective for fat loss? Is one dangerous? Is one heads and shoulders better than the others? In a 12+ hour fasted state, each of these will use fat for fuel.

Still waiting to hear why it is important.

I think there are two questions or issues being discussed. One is when he objected to my statement "I did workout during the fast so I had to have been using some bodyfat for fuel " I still stick by that statement. Clearly if I was doing aerobic type of exercises in a state of ketosis, I was using fat for fuel. I think we are in agreement there.

But even if I did solely anaerobic exercises, I was still burning some bodyfat for fuel. Disregard that the fact that the anaerobic threshold has probably been moved (as his testing has shown). But in ketosis, you are still burning some fat for fuel and not relying 100% on glycogen while doing anaerobic exercises. Fattyman007 even said he gets 15% of energy from fat during this state. So there is some agreement there. In addition, when doing high intensity anaerobic, you get a post exercise metabolism increase. Since this is in a glycogen depleted, oxygen-available state, you should be burning fat. (yeah!)

The second issue was my repeated requests for him to explain his statement "Its important for any one on low carb diets to understand what happens in high intensity workouts." Is the importance JUST that you may not be burning as much fat doing high intensity than you are doing low intensity exercise? Or is it something more significant? It would be significant if there net muscle loss due to gluconeogensis from anaerobic exercises in a glycogen depleted state. Is that the case? (I have read studies that show low carb diets are muscle sparing compared to other weight loss diets, however, I do not remember if these included weight training or not). This is why I kept asking why is it important. He even used the word "dangerous" so that implies the importance is more than just the fact you will be burning less fat compared to an equivalent amount of aerobic exercise.

With diabetes in my family and with some signs of pre-diabetes I have done a lot of research and weight lifting continues to come up as a great suggestion for diabetics as is low carb diets. However, regarding anaerobic exercise and low carb, Fattyman007 has stated the following quotes"

"The last thing you want is go low on carb and switch the body to use glycogen or ATPs produce by lactic acid in a work out. "

"Its important for any one on low carb diets to understand what happens in high intensity workouts. "

"I wouldn't put my body running on lactic acid or put my liver in over drive when you are glycogen starved. "

"And please don't make statements like I am fasting and thats why I am burning fat in high intensity workouts. Its dangerous advice. "

So again I ask, what is important? Is it just that I'm not maximizing fat loss or that I won't be at peak performance? Or is it truly something important (for me)? He is suggesting I don't lift weights while low carbing and would like to know why...

Perhaps I am obtuse. Maybe you (birdiecs) can simplify it for me, why is it important NOT to use glycogen or lactic acid to make ATP while doing low carb? This seems to be important, but I'd like to know why. Take it a step further, that is all I am asking.

Fattyman007 - sorry if I inferred that you recommended not doing weights on low carb. But in trying to figure out for myself the answer to my question, my line of thinking was weight lifting--> anaerobic-->need quick fuel-->can't use fatty acids quickly-->uses lactic acid/liver glycogen instead-->"I wouldn't put my body running on lactic acid or put my liver in over drive when you are glycogen starved. "

That is why I thought you implied not to do weights during low carb. The incorrect step in this thought train is that weight lifting is not anaerobic? If you'd rather, we can discuss this through private message, but others might be interested in this discussion.