I would expect that those in the study were on the SAD and are carb-dependent. What about those of us that have switched to fat burning as a primary source of fuel? I work out fasted and have noticed remarkable gains in both strength and physique.

I train fasted but I can be convinced to do otherwise. I chose fasted training due to what I've read on Leangains, Hofmeklers' newer stuff about recycling old muscle proteins and Art Devany's book.

I exercise first thing, and it's really a matter of convenience to do so before I have to cook everyone their eggs.

The types of exercise I do are heavy weights, sprints, and mixed up metabolic conditioning stuff that I make up myself. I don't run or pull on the ol' leg warmers for aerobics.

My goals are to increase upper body strength (my chins and pull-ups are kinda pathetic), wake up my dead glutes and grow a strong powerful booty, and develop an iron clad core so that I won't have to have the bladder surgery that my mother just had.

I haven't gone up in weight recently, my deads are dead. I'm not any closer to a Sarah Connors pull-up either. SO, prolly I'll rethink the whole fasted part and see how I do.

I run, swim or do other moderately intense cardio (oh noez, cardio!) fasted a few times a week. My long run for the week is usually fasted. I don't really care much if there's a fat burning advantage or not, I do it because it makes me feel really good, and honestly, I feel like it's good self-discipline. It's also a good reality check for the idea that cardio is a free pass to eat a ton of extra food, if that makes sense. I actually used to do all my cardio about 14 hours fasted, but I stopped that when I noticed I had stopped improving my performance and was just generally feeling shitty.

Thanks for sharing. This will be useful to consider once I actually begin training.

Because I practice "change-it-up" as a primary strategy in my battle with my body, which is a metabolically challenged ex-fattie body, I will continue to do what I am doing. I workout about 80-90% of the time fasted. I was never able to do this before about the last year. Prior to that, I was still so metabolically deranged that I still did a form of graze-eating.A huge benefit for me is that if I practice IF, I do not get hungry after exercising. If I have the nice big breakfast recommended in some circles, I am a postergirl for Taubes etc "exercise makes you hungry." With IF, no no hunger.

Also, in Chris Kresser's podcast #1, Stephan Guyenet touched on the possible effects of IF resulting in more leptin to the hypothalamus, which can only be a good thing in my world.

I believe that IF at the level I do it, combined with change-it-up in all aspects of my life , but most focused on diet and movement/exercise, is over time, changing my set-point.

I train fasted but I also cycle, have Crossfit, and then my own WOD's outside of the box, early in the morning. Years of swimming practice at 5am for two-hours set me up and it's just how I do it. Afternoon practice was of course after eating meals and really couldn't tell the difference. That was before I went Paleo. Now what I do is the night before I go into the box, as the WOD's there are always awesome crushers and take way more out of me than my other sporto activites, about 30-mins before bed will have a hardboiled egg, some mac nuts, coconut, a few bites of sweet potato. I have more energy and very little slow down the next morning - all solid performances since I made that change. I was just blazing through all my food too fast and now the late night snacks then to sleep has really been aces. My coaches approve as well so I'm doing it right - at least for me. Also, it's more important to me to kick ass and feel good than to care about all the fat burning bloddy blah. I don't care about that shit. I'm healthy. I eat big in the right ways. My workouts are productive. I feel and look amazing and each day it gets better and better. That's kind of all that matters, right?

I think it depends on the individuals metabolic flexibility(the ability to switch between fat and carb burning or the Respiratory Exchange Ratio).

Beta-oxidation (fat-burning) produces less carbon dioxide than glycolysis (sugar-burning)—and we can measure that in our breath. The ratio of CO2 to O2 is 0.7 for beta-oxidation and 1.0 for glycolysis…so an RER (Respiratory Exchange Ratio) of 0.7 indicates pure fat-burning, and 1.0 and above indicates pure sugar burning.

If someone has a high fasting RER(sugar-burning) it indicates they are less than healthy and are burning less fat, so it seems like it is beneficial to train fasted so they can train their bodies to burn more fat.

If someone has a normal fasting RER(fat-burning) then eating before working out could be beneficial if they are trying to gain lean mass and they should easily be able to switch from fat to carb burning so they should burn the same amount of fat regardless.