Studies: Intermittent Fasting Thread

[CFC]

Some of you may have missed this new study published last week, that determined some minor body composition and health marker improvements from a 'Leangains' style intermittent fasting (IF) protocol (eat for 8hrs; fast for 16hrs). This is the first published study to assess this specific style of IF in trained male athletes, so has been well-anticipated and discussed online.

To quote from the study: "Our results suggest that an intermittent fasting program in which all calories are consumed in an 8-h window each day, in conjunction with resistance training, could improve some health-related biomarkers, decrease fat mass, and maintain muscle mass in resistance-trained males."

However, the changes are pretty minor, the study was only for 8 weeks, only in men (women may respond quite differently), and calorie consumption before the study was neither properly controlled nor properly measured during the study (by recall, which is a notoriously poor method). It's been suggested elsewhere that the IF group may already have been in a mild calorie deficit, and that this study is really just picking up those changes.

Anyway the full study is free, so check it out and make your mind up yourself. I'll reproduce Table 3 results from the study, with the health markers and parameters, for you here:

If that's a little too dry for you, Strengtheory have kindly taken the time to review the study >>here<<, with a few more snippets of info and some decent critique of the work.

If this has you interested in trying out an IF protocol for yourself, you may first like to have a look at Bojan Kostevski's much broader review of IF practices undertaken for his doctorate in 2012, which you can find >>here<<

And if you want to read a little deeper still, you can check out Martin Berkhan's Leangains website >>here<<, and finally there's Ergo-Log's archive of IF-related studies and analysis to swot through >>here<<

Enjoy!

 

[RedLeader]

I skimmed this and will have a better look later on. Thus far I have never seen anything that suggests that calorie-timing has any effect on fat loss. I'm a bit more on the fence when it comes to muscle retention, as I have read stuff arguing both sides of this. And I don't think it's optimal when it comes to anabolism (IF with the exceptions of periodic protein and/or BCAAs could be better, but is this still IF?). I know that Kinobody and that crowd will ramble on about IF and GH, but as Layne Norton explains, this is from a fuel-mobilization standpoint and that such transient rises in GH, if they do occur with IF, are not anabolic for muscle tissue. And then there is the issue of protein distribution and if getting all of one's protein within a 6-8 hour window would be inferior to more widely-spread protein meals (I guess this has been shown to be the case in some animals). I do think that it could indirectly help with fat loss in that if one feels better living under the IF framework, one may sleep better, feel less stress and be able to train harder, and those things absolutely help with fat loss.

I have used 18/6 IF in the past and it "worked." I use the quotes because, and perhaps similar to this study, I don't know if it worked ceteris paribus or if it worked as much as the entire shift in my diet/exercise worked toward my recomposition goals, though I'm leading toward the latter. Going forward with the goals I now have, I don't think that IF if necessary or sufficient to meet them. I think that IF comes into its own when it comes to managing hunger and controlling binges. And, noting that this is total broscience, if I do have a cheat meal, I often feel better doing IF on the day of the cheat meal. My work gave us pizza on Monday for example, and I ate 2750 calories of pizza in one go, and just let that be my only meal of the day.

People need to understand that IF is not a diet as much as it is a system, in a way like IIFYM, inside which actual diets could be used (I did hear about some researcher [I think it was on one of the BB.com roundtables] suggesting synergy between IF and ketogenic dieting, but the details escape me). I suppose I kind of IF a bit with my macros, though. I will have 6-8 servings of 20-30g protein around-the-clock, but then time my carbs around my workouts and my fats around my downtime.

 

[CFC]

IF with the exceptions of periodic protein and/or BCAAs could be better, but is this still IF?

I couldn't personally even begin to describe that as 'fasting': you could cause quite an insulin spike with that approach.

With the IF debate and sub-debates, I'm reminded of the never-ending discussion around optimal forms of cardio and HIIT, and where to slot them in your workout, and so on. I generally prefer the method called 'whatever works', since in the longer perspective that will always be the most effective. But I'm still pleased they do look at methods that may lead even to minor improvements and/or slightly better generalised advice.

I agree with you that carb-cycling is possibly more efficacious than typical forms of IF for most folks, particularly when bulking. With clients I tend to stick to that - unless they have a preference for a specific type of IF or happen to genetically respond well.

The 'IF' types I've generally found more effective are where fasting occurs over longer periods (2 days or more), combined with ample LISS. But generally any practice that helps maintain superior insulin sensitivity would be strongly advised, be it carb manipulation, types of cardio, fasting or pharmaceuticals.

 

[RedLeader]

Ya, I have essentially two lists: 1) things I do every single day no matter what and 2) things I try and do on days when life does not get too complicated. Hitting my macros falls into 1), meal and macro timing falls into 2). I'm bulking now, so I am a bit less strict, but on my next cut list 1 will absorb from list 2). My personality is one where I do obsess, so it is actually a challenge for me to not always be obsessing and reading about new things to put on 2). The stress of conflicting literature/research/studies/opinions, having too many little ideas on this list and having the optimization word always on my mind probably negatively affects me to a greater degree than any of the potential positive benefits of these topics. As you mentioned, in terms of stability and longevity, perhaps less is actually more...