The FastDay Forum

Before long endurance events it is thought beneficial to be at the starting line with your large muscles filled to the brim with glycogen. The process of "filling you up" is called carb loading.
Some articles here:
http://www.theglobeandmail.com/life/health-and-fitness/fitness/carbo-loading-is-it-key-the-day-before-a-marathon/article1359197/
and here (more of a guide)
http://www.runyourbq.com/carbo-loading/
And a more science based one:
http://sciencebasedrunning.com/2011/06/carbo-loading-an-idea-whose-time-has-passed/

In general the opinion is that you need not carb load for anything shorter than a marathon.
What are your experiences?
Recommendations?

Not forgotten, just uncertain about how to comment. For a recent counter-point of leading edge research, consider this book:

http://www.amazon.co.uk/The-Art-Science ... ords=volek

While carb-loading can work for distances up a marathon and neatly fits within our carb-intensive societies, I feel that going low carb and becoming fat-adapted is the way of the future. The former is still being championed by the sport media (eg: Runner's World magazine) and their resident nutritionists. But aren't those within current paradigms always the last to consider the possiblities of alternative ways of thinking?

[carorees]

Partly this is a context problem. If you are not fat adapted, you have to carb load just to get through the distance, if you are fat adapted, carb loading should be unnecessary and may even worsen your RQ?

Partly this is a context problem. If you are not fat adapted, you have to carb load just to get through the distance, if you are fat adapted, carb loading should be unnecessary and may even worsen your RQ?

That's pretty much the way I read it.

Paraphrasing both of V/P's books, "RQ = Respiratory Quotient is the volume of C02 produced by the body divided by the volulme of oxygen consumed. Glucose 'burns' in the body with an RQ of 1.0, and fat at .7. Being fat-adapted reduces RQ whereas lipogenesis raises it".

Further: "...subjects adapted to low carb diets typically see an average RQ well below .8 even during moderate intensity endurance exercise... which is consistent with someone burning less than 100 grams of total carbs per day with most of the rest coming from fat."

Walkers can finish a half or full marathon nibbling MM's all the way without ever hitting the wall because their glucose/glycogen replacement rates meet their energy outgo. Of course they are out there for 3 1/2 to over 7 hours. Those a bit faster can do the same (in less time) by ingesting, for example, 3-6 100+ calorie "goo" packs (maltodextrin, a complex carb) respectively because their digestion is still reasonably functional. Much faster racewalkers and runners increasingly face the problem of beating their carbohydrate clocks by carb loading (problematic), or being athletically efficient enough to avoid it with training.

I can't imagine you can be fat adapted to a point where it equals burning carbs? Of course long endurance events can be done, and even nicely, but the way our muscles are built (to my knowledge) there is no reason to abstain from filling up your glycogen reserves as mush as possible.
The top performing people eat carbs all the way, trying to keep up with expenditure, but eventually everybody loses. It's impossible to eat and digest fast enough while performing.
As far as I know there is no pure fat burning? The muscles will always need some carbs in the equation?
I'd like to think "Carbs are evil, except when they aren't" and that is when you spend a lot of energy or you have to in a compressed time (crazy as it is).
From my point of view starting a long endurance event on "half a tank" is asking for trouble. That's not the same as your glycogen depots being filled by eating sugar. That's the amateur's easy fix (me amongst others). But can you fill your glycogen depots on a low carb diet, while training? Will the body use body fat and move it to the muscles as glycogen, given the input of carbs is too low to do the job?
One of the fastest endurance runners live on a diet of fruit only (so called "Fruitarian") Not that I would recommend it it any way, but it gives thought to the body's ability to use what is thrown at it:
http://www.thefruitarian.com/

Also if you look at the Kenyan runner's diet, my eyeballs popped out:
http://runnersconnect.net/running-nutrition-articles/diet-of-kenyan-runners/

Oh man.... My eyeballs popped out too 600gms?!?!?!?!?"

Given the immense variation of causal genetics, training, available foods, running styles, and a host of other confounding factors there could be a Twinkie-eating guy out there somewhere that'll come across a system that works ideally for him.

From Peter Attia's perspective what matters most is "knowing your engine" - finding what works for your special combination of the above for whatever you choose to pursue.

This article is a good place to start:

http://eatingacademy.com/sports-and-nut ... n-co-exist

And this article gets right to the heart of your questions:

http://eatingacademy.com/how-a-low-carb ... erformance

Thanks @ADFnFuel and @carorees
ADFnFuel, this guy is extreme, however much can be learned. But I think going ketosis is over the top for most people. It would certainly be a bye bye to the social and relaxed part of 5:2.
However, there has been much writing in these forums about "Can I train fasted/while fasting" and similar questions.
And behold:
http://runnersconnect.net/running-training-articles/cience-of-bonking-and-glycogen-depletion/

Yes, and it will benefit you if you are into endurance sports.

More goodies from a Danish triathlete, how he maximized fat burning capability:
http://triathlon.competitor.com/2012/06/nutrition/inside-triathlon-magazine-fat-burning-machine_31034

Have been an experiment of N=1 since May 24th - having deliberately gone very low carb (<50g). What better way to test theories, right? So far I've noticed that for 5K's , 10Ks and ~8 mile (13k) distances that my times are a bit slower. Times for the first two are improving; too little data for the last one although they've been close.

Being only 7 days in, and since adaptation is estimated to take three weeks or so, I'm going to stick it out for at least two more weeks, to see if distances/times improve. Morning weight has dropped around 2-4 pounds (1-2 kg). I've a half-marathon at the end of June so this experiment may get real interesting in the time remaining...