I don't run, so I have no knowledge of the issue, but I do follow Dr. Tim Noakes on twitter and he discusses athletic performance and the LCHF diet all the time. I think if you dig through his website you might find some answers. I found this as a start. It's a podcast.

https://thenoakesfoundation.org/nutrition-network/fat-adapted-do-you-need-carbohydrates-if-running-on-the-lchf-diet

Research the idea of carbing up or Cyclical Ketogenic Diet for an endurance event by google/searching those + Dr. Jeff Volek (#1) or Lyle McDonald or (perhaps) Dr Jacob Wilson (more into body building IMO) just to name a few.

Or summon @anubis609 who seems well studied on ketogenic diets in combo with athletic performance.

Marathoners who have been fat/keto-adapted anecdotally feel much better in endurance sports whether they run fasted or fed, typically because the "bonk" or "wall" doesn't get hit, or at least not as soon as high-carbers.

I'm not a shill for Vespa, but I can vouch for their training program and products since Peter Defty, the head of the US corporation, worked closely with Phinney & Volek in their FASTER study for endurance athletes. http://www.vespapower.com/ofm/what-is-ofm/

As far as being keto most of the time and then carbing up prior to a long run, that's actually a strategy used by keto/low carb runners. In that sense, carbs almost become an enhancing fuel since your body can now burn through the carbs you stored the night before but your body will also shift over to burning fat once those carbs are depleted, essentially never bonking in that transition.

In summary, the motto to "train high and perform low" would mean you train harder than you compete, that way, competition day actually feels like practice. So, you train your runs either in a keto or fasted state, then come race time, do a carb nite, and run your *kitten* off with relative ease on race day.

In general, that's true for carbs to provide bursts of energy, but the purpose for endurance/ultra endurance race carbs is that as a fat adapted athlete, you have the advantage of being able to use two fuel sources. Think of carbs like diesel fuel to give you a good lead and once that depletes, your body switches over to using fat to sustain that pace, as if switching over to an electric motor. Intermittent fast carb gel packs provide boosts in energy as the terrain/pace demands.

Ideally, the athlete will be metabolically flexible enough to handle the switch from glucose to fatty acids without feeling the effects of that shift. Which carb-dominant athletes describe as "bonking." Fat adapted athletes are used to that feeling so it's like a natural state for them to be in.

Smoked33 wrote: »

anubis609 wrote: »

I'm not a shill for Vespa, but I can vouch for their training program and products since Peter Defty, the head of the US corporation, worked closely with Phinney & Volek in their FASTER study for endurance athletes. http://www.vespapower.com/ofm/what-is-ofm/

While not competing in full marathons I can vouch for fat adapted running up to 10k and I definitely perform better with no fluids or foods to sustain me than on a carb based diet.

Interesting from this article is the stressing of keeping protein to less than 30% of your total calories. This is definitely in opposition to the widely held belief of many of this group's members that protein should be high.

As with most things, protein intake is also contextual. Macro percentages are only as accurate as they pertain to total calories. Since endurance athletes will need adequate energy intake to sustain their training, 30% of calories coming from protein is going to vary depending on calorie intake. Assume an athlete requires 3000kcal/day, that's 900kcal coming from protein, which is 225g of protein.

On the other hand if the athlete is only eating 1000kcal/day, then 300kcal coming protein translates to 75g of protein.

Between 75 - 225g protein is a large gap and each are 30% of total calories in their respective examples.

For context, being able to vouch as a fat adapted athlete, the majority of your total calorie intake is going to be coming from dietary fat, and protein being roughly 56% anti-ketogenic, the recommendation to provide a fuel source that isn't carbs, is going to make fat the primary substrate by process of elimination - protein is not an optimal source of energy.

For most other non-endurance athlete people following keto/low carb, protein is essential for this reason alone:

3b. alternative conclusion: Low carb diets aren’t muscle-sparing and even appear to be the opposite: you need to increase protein to attenuate muscle loss on this diet. These LC dieters increased protein by 10 g/d and still lost more muscle than LF dieters, whose protein actually declined by ~10g. If LC was muscle-sparing, the exact opposite would’ve happened. It didn’t. Please don’t hate me for this.

From Bill Lagakos: http://caloriesproper.com/protein-ketosis-and-lean-mass/

Here is my understanding, though most of my research has been based around strength training or mid-distance running, not exactly what you are doing. And this is just my understanding, I'm a computer geek, not a scientist, so it's worth what you paid for it.

Most people burn carbs easy - it's what most people grow up eating and therefore our bodies have the mitochondria for the glucose metabolic pathway. When you keto, it's an alternate metabolic pathway, so your body builds mitochondria for the ketone metabolic pathway. Once you are "fat adapted" you have plenty of ketone mitochondria and you are able to go long periods of time with little or no carbs without any drop in energy levels.

Now, when you eat carbs, your body does 2 things immediately. 1- it puts glucose in your bloodstream. 2 - it stores glucose in your liver and muscles for future use.

If you eat too many it will also shove glucose into fat cells, but lets assume you are just eating a normal carby meal and you aren't diabetic or any of that, so metabolism is working in a healthy fashion and you aren't getting fat.

When your body has glucose in the bloodstream, that's what it uses for energy. When it runs out of glucose in the bloodstream it tells the liver to release stored glucose and move it into the bloodstream. When your liver is out of stored glucose, it starts turning fat (consumed first, then adipose) into ketones. (muscle glucose is used somewhere in there too based on how hard the muscle is working and how fast the body can circulate glucose to it - not sure of the order of operations for the muscle glucose)

On to the point - your body knows the difference, and it likes for BOTH forms of metabolism to be available at all times - we are primarily designed to survive starvation, it's a cool thing. So, when you go keto, then you actually stimulate your body to store more glucose in your liver and muscles when you do eat carbs - because your body knows it ran out and didn't have enough last time so it figures it needs to store lots more this time. (both in the liver and in the muscles, though you can also stimulate muscle storage with weight training while keto or fasted). When you are keto, eating a high carb meal 12-24 hours before any physical event should boost performance because it's like Christmas for your body, it suddenly has all this glucose to circulate and give to the liver and give to the muscles and it's super happy about that because it hasn't had any in a while and it's greedy and it wants to keep it all available for later because it doesn't really want to run out ever again. So, you trick your body into having plenty of resources available for your physical activity.

Arnold Schwarzenegger used to cut fairly low carb (in relation to carb levels consumed when bulking) and eat pies the night before a competition, because all that glucose (which is stored in water) swells the muscles and makes them visually bigger. But, it should also make you have more energy, the vanity aspect is just a bonus!