intermittent fasting ok for athletes?

[MMouse]

I'm on my phone right now and can't fully comment, but essentially you've misinterpreted all of those studies and you're making incorrect conclusions. I've read all of those papers and know the literature on fasting like the back of my hand. I'll go into more detail when I get to a computer.

this should be interesting

 

[Seriously-Dead]

Fixed that for you. I don't mind if you dismiss IF in your own training routine, but don't scare other athletes away from experimenting with it. See below:

http://www.ncbi.nlm.nih.gov/pubmed/23582559

http://www.ncbi.nlm.nih.gov/pubmed/23266375

http://www.ncbi.nlm.nih.gov/pubmed/23171320

http://www.sciencedaily.com/releases/2013/04/130426115456.htm

IF is admittedly in its early days of serious scientific study so there will surely be more studies to come and more specificity around its benefits. That said, it's patently erroneous to state that evidence doesn't exist showing that fasting has a positive effect on repair, healing and weight management.

Additionally, the community of individuals who use fasting regularly for its benefits largely drive interest from the scientific community to validate these benefits with studies. Water fasting has been a therapeutic protocol since antiquity and for reasons that we're just now understanding biologically.

What's erroneous to state is that fasting is good for athletes. Athletes being people who train at least once per day, 5-7 days per week. None of those studies you posted have anything to do with that.

I can see it in your brain now, you're banking on that muscle damage study - the other studies obviously have nothing to do with athletes, but that one is as close as you'll get. Well, fasting decreased serum markers of inflammation so it has to be good, right?

Well let's take a closer look.

Study Methods
This is an 8 hour fast, not a 16-20 hour fast like most people do fasting. The "fasting" group could still eat a hearty breakfast, and could eat anything they wanted to up until 8 hours before the mid-afternoon test. This is not "intermittent fasting", it's eating a late lunch. This much is enough to discredit the idea that this study infers anything about intermittent fasting as it relates to muscle damage, athletes, or sport performance.

A study that actually tests this would use a design where people fast for 16-18 hours per day, while actively training for a competitive sport 1-2 times a day 5-7 days a week. The study you linked is not that study. Anyway, I'll move on to another point.

Outcomes
It's important to read past the abstract in this study, and I'll quote the authors Discussion section to highlight that importance.

However, the groups did not change differently across time for any other [other than reduced loss of elbow extension] outcome measures. Thus, it appears that fasting did not offer robust protection from exercise-induced muscle damage.

Most importantly, and the authors of that paper are aware of this, reduced TNFa and higher NO is not necessarily better for exercise adaptations (there is no evidence this is the case).

To quote the authors again, you'll see that they realize how fragile their study design is, and that the outcomes don't really prove anything definitively:

With consideration of these limitations, our preliminary results suggest that intermittent fasting does not inhibit the signs and symptoms of exercise-induced muscle damage. However, 8-h water-only fasts on five consecutive days may generally affect inflammation and oxidative stress. Investigators interested in dietary interventions for the sequelae of muscle damaging exercise should consider pursuing additional studies of fasting based on these findings and the issues raised here.

You don't have to lecture me on the potential health benefits of Intermittent Fasting - I'm running a study on it right now and seeing the results first hand in Type 2 Diabetics. But I'm not so silly that I'm going to say it's panacea for everyone, especially athletes. It's a treatment that works for some populations, and for others it makes things a hell of a lot worse.

 

[anaconda]

What kind of protocol are you using for the type 2 diabetes study? I'm really trying to get my mom to incorporate some fasting since she is dangerously pre-diabetic.

 

[DaTruth]

The protocol is just a 18 hour fast and 6 hour feeding window. No regulation of food or exercise, just feeding window only. I believe the 6 hour window was chosen because of potential error correcting for a 8 hour feeding window.

 

[Seriously-Dead]

What kind of protocol are you using for the type 2 diabetes study? I'm really trying to get my mom to incorporate some fasting since she is dangerously pre-diabetic.

Like DaTruth said, 16-18 hour fasting - but the participants are allowed to auto-regulate. Women have a tendency to autoregulate down to about 14-16 hour fasts, and they are just as effective. Anything over 16 hours for women was typically too much, and they'd start presenting with symptoms of hypoglycemia around 18 hours.

We've also instructed them to eat high protein and drink lots of coffee and tea, since both habits have anti-diabetic properties, so it's essentially Berkhan's LeanGains protocol.

 

[anaconda]

Like DaTruth said, 16-18 hour fasting - but the participants are allowed to auto-regulate. Women have a tendency to autoregulate down to about 14-16 hour fasts, and they are just as effective. Anything over 16 hours for women was typically too much, and they'd start presenting with symptoms of hypoglycemia around 18 hours.

We've also instructed them to eat high protein and drink lots of coffee and tea, since both habits have anti-diabetic properties, so it's essentially Berkhan's LeanGains protocol.

Awesome, thanks! I'll have to discuss this with her. I was trying to get her to at least do 24 hours once a week, but I think the psychological hurdle is too big. 16 hours is doable I think.