bikenh

I saw a video last night, won't post the link. It got me to thinking quite seriously about a whole combination of things, from things I've experienced to things I've heard.

Bonking, by definition, is when the body runs out of sugars to fuel the body and you start burning body fat. As a result of fat not being as much of an efficient burning fuel source you start to slow down and start to feel run down(personal experiences).

Does the body get used to using fat, if you give it the chance, so you will increase your overall speed back up to something more 'normal' if you continue to ride long term while bonked, aka burning fat versus burning sugar? Can the body adapt to that and still perform at high levels?
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By long term I'm not talking hours but rather days and weeks long. I'm not talking 'bonking' in the normal fashion but rather bonking in the definition fashion...like if all you ate were fats and no sugars.

I warned you it was a rather strange question...didn't I

steve-in-kville 

I don't want to start a debate that will get out of hand, but check out the Paleo lifestyle and google Ketosis (sp?). Yes, a body can become fat-burning adapted, I've done it, with varying results.

Steamer

Look 4 threads down.

nycphotography

Fat adapting is a thing (and it's a big part of base training and structured training), but you don't fat adapt by bonking. You fat adapt by riding lots* of miles while managing your exertion level and heart rate, and not consuming tons of sugars / drinks / gels / bars.

*Lots = less than would cause you to bonk, but enough to deplete glycogen, while at heart rates that promote (aerobic) fat consumption for energy.

Carbonfiberboy 

Not strange, heard it before. It is an interesting question. Yes, you can burn fat. No, you won't go as fast burning only fat.

It's proven that riding for several hours at a time at about VT1 without eating will encourage fat burning. This is very helpful. It's been called "bonk training" but in fact it has nothing to do with bonking, since the rider is well fueled with glycogen and simply burns very little of it, thus riding for hours on fat alone. That seems to be helpful for long distance endurance.

Be that as it may, in reality RAAM riders eat as much as they can, mostly carbs, a little protein, a little fat. I don't have a reference for the diet of round the world cyclists, but from the info I've seen they eat whatever they can and as much as possible. Probably again mostly carbs.

The problem is speed. If you want to ride fast, it takes carbs. Your body will burn as much fat as it can, but there are limits to how many calories/hour can be summoned, hour after hour.

There are those who claim that if you eat only fat and protein, you'll burn fat better on the bike. So far the hypothesis that eating fat causes more fat burning than does riding at a fat burning pace remains unproven. IMO the opposite is the case, witness the RAAM riders who could most benefit from fat burning . . . eating carbs.

I think the problem with eating a lot of fat is that it doesn't go across the stomach wall fast enough to provide the necessary energy. Say you burn 6000 calories/day. That's about 2 lbs. of fat. Not that many long distance riders have an extra 20 lbs. or whatever of fat extra. So success in long distance racing really comes down to how much can you eat without barfing or slowing and how fast can you get it across the stomach wall.

One of my favorite long distance "meals" is a Hostess Fruit Pie. That'll hold me for an hour or so. Nice balanced meal, eh? Mostly it only takes me 2 minutes to eat and I'm gone.


Edit: I should mention that your body gets better at what you train it to do. Ride moderate at a fat burning pace, it gets better at burning fat. Ride hard at a carb-burning pace, it gets better at burning carbs. IME it's unwise to neglect either of those.

seedsbelize 

I was once on a completely sugar free diet (including no fruit or sweet vegies) and my body had no choice but to burn fat for energy. Once it adapted, it worked out very well. I was doing three centuries a month during that period, and was dropping weight at an alarming rate. I was in my late 50s. But to do it in the manner you describe would just be a plain old bonk. When I bonk, I have no choice but to get off the bike, and frequently am very disoriented.

jhaddad8

I'm excited to see how many responses this question has gotten since I was asking about the same thing, a low carb high fat diet for endurance training just a few posts down. I've been researching the usage of a LCHF diet for randonneuring for a few weeks now and began following the primal diet last week. At this point, personal experiences are limited, and I'm expecting about 3 months to see performance changes. I don't want to weigh you down with my own explanations so I've attached a whole bunch of links.

Trans American Race finisher and fastest woman around the world has adopted a ketogenic diet recently and talks about it a bit on her blog. Keto Baby! - Juliana Buhring

The primal diet that I am following has its main website here.
https://www.primalblueprint.com/learning-center/

No links included but there is a book also from Mark Sisson called primal endurance and there is also a podcast by the same name. Investigating those resources will provide you with tons of information on the topic.

One other point, Mark Allen who may be the greatest Iron man triathlete has apparently been on a LCHF since his racing days. I've heard good encouraging information, and I'm convinced it's worth a try. I would love to here other personal experiences of people here and am particularly curious to know how long it took

Drew Eckhardt 

Bonking is when you run out of liver glycogen. You're already burning fat when that happens.

You slow down because exercise is powered by an intensity, training, and diet dependent mix of carbohydrate and fat which could vary from 20% glycogen / 80% fat at an endurance pace to over 80% glycogen and under 20% fat at lactate threshold.

Things don't work right when you don't have those stored carbs.

You can get more energy from fat, but you won't be near normal when you run out of glycogen,

You can increase your performance below your aerobic threshold (AeT, VT1, where conversation flows, breathing isn't rhythmic, and lactate doesn't accumulate) by training below it. Perhaps not coincidentally that's near the heart rate returned by the Maffetone formula.

With training larger riders should be able to manage 20 MPH on flat ground below AeT, smaller 18 MPH.

After dropping his training pace below his aerobic threshold (8 minute + miles) Mark Allen's slow pace increased enough to set a 2:40 Ironman marathon split record in 1989 which still stands.

Seiler found that Ironman triathlon performance was positively correlated with training time below athlete's aerobic threshold, but negatively correlated with time between itand their anaerobic threshold.

Your body will make sugar via gluconeogenesis when you're not eating enough carbs, although that can't happen fast enough to keep your glycogen stores topped-off while riding.

100 km should be fine, 100 miles might be, but going farther you'll need to eat carbs.

BikeLite

At all times the body is burning all fuels (carbs, fats, protein) to run different cell types. You are mostly only talking about skeletal muscle where the percentages change with exertion and adaptation.

ARTICLES | Journal of Applied Physiology

Carbonfiberboy 

On a long ride a long time ago, I was forced off the bike and sat in a ditch while the world strobed around me. I ate a Clif Bar and was fine in 15 minutes.

bikenh

What I'm referring is a bit more extreme than LCHF. Ketosis, well I heard the word ketosis being used on several different videos now talking about the idea I'm referring to.

My prior experience, before I got back into biking(admittedly), with long term(14-20+ days) fasting has now led me to really question the concept. My most recent fast back in 2009 ended fine, no problem until 5 days later when I had a rather weird response. One part of the response was a non drug induced high on night one and then a non-drug induced low the second night. Didn't sleep either night. I forced myself to lay down morning #3 and grabbed a 30 minute nap...otherwise I was awake for 60 straight hours doing nothing more than sitting in front of a computer..ho physical activity of any kind. No drugs, no caffeine, no nothing to help me stay awake other than I was coming off having the digestive system having been shut down for 20+ days. While on the fast I didn't notice anything in terms of unusual sleep, it all came afterwards.

I realize combining something like a fast with heavy duty exercise would cause very quick weight loss. I also realize and it is quite well reported about also not having to sleep as much when on a fast due to the lack of an active digestive system causing less need for sleep.

Looking at the guys(Strausser and others) that use a pure liquid diet and the way they have much better luck with sleep deprivation...

Yes, they are still getting calories from the drink mix. I do understand that.

I do admit I tend to think the effect of something like what I'm suggesting would give the same kind of feeling/experience as bonking. In both cases you are going on fats not sugars, at least by my definition/understanding you are. Hence why I titled the subject the way I did.

Yes, a bit of a strange concept to say the least.

ThermionicScott 

Ketosis was regarded as some kind of magical state when low-carb diets became trendy a few decades ago, but it's not really essential for what you have in mind (or any of the fad dieters.)

One thing I enjoyed about Atkins when I tried it for a couple of weeks in college (hey, college is where you try dumb stuff) was the more consistent alertness and energy levels, now that I wasn't having sugar rushes and crashes throughout the day. Perhaps you forced yourself out of other bad habits during your experiment.

And quit using the word "bonk" to describe running solely on fats. The term has a very specific meaning, and you'll never stop confusing yourself and other thread participants if you persist in trying to redefine it.

bikenh

I have always heard the definition of bonking as being when your body has used up its sugars and it starts burning fats instead. Since fats aren't 'normally' as fast at being converted into energy is why you tend to slow down when you bonk. What have I said that is incorrect? I mean the question honestly. You're trying to suggest what I said is wrong. Isn't glycogen(if you want to start getting into bigger terms) nothing but sugar?

steve-in-kville 

One never forgets their first bonk! I view it as a state of being.... or not being!

Seriously, I tried the LCHF thing for two months. Its hard. It can be done, but few folks have the discipline in themselves to do it. I am a huge fresh fruit eater and that made it even worse. I think I even had some test strips to test my urine to determine whether I had reached true ketosis or not.

NYMXer

I could be wrong here but "bonking" and "fat burning" are not the same, or even close. Fat burning, or Ketosis, is when the body switches from seeking energy from converted carbs, aka "high energy but short duration. Ketosis is when the body seeks energy from stored fat reserves, which is already broke down and ready to use but offers more linear energy for very long durations.

It's like comparing a gas engine to a diesel engine. Our bodies were designed to burn fat but have adapted to burn carbs since we are now better shoppers rather than good hunters.

Carbonfiberboy 

That's a very good question. It may be more complicated than you think. My opinion is that if one has been in ketosis long enough and ingesting pretty much zero carbs for long enough (4+ days), one's brain starts running on ketones instead of glucose, its normal fuel. Yeah, so then you can't bonk because your body can operate everything with no sugar at all. OTOH if your body hasn't had time to make this adaptation, or you normally eat some carbs, then when you run out of glucose, your brain shuts down, which is the real bonk.

Sometimes when I've been doing a lot of base training, I'll reach a state where I'm pedaling just fine at a moderate pace when all of a sudden my liver runs out of glycogen and I don't feel good at all. Just a little sugar gets my brain back in operation and the muscles continue as before, since they're already running almost entirely on fat.

https://en.wikipedia.org/wiki/Ketone_bodies

ThermionicScott 

I've only ever heard it used to describe using up your stored glycogen while exercising, and completely running out of gas, physically and mentally. "Zombie-mode" would be apt.

On the flip side, it's possible to be "fat-adapted" and ride long distances without bonking. It takes that adaptation and pacing yourself just right, being careful not to burn any more matches than you have to.

bikenh

I think this might be the key difference and after you say 4+ days it instantly hit the trigger with me. I hadn't stop to consider a time line difference between bonking, short term and longer term riding on fat. Yeah, I could/can see there being a difference between the two when you put in that perspective.

downtube42

Yum. I find Rice Krispie Treats have a similar effect and are more durable, though not nearly as tasty.

thebulls

After reading some of this and other threads, I've decided to give LCHF / ketogenic diet a try. I only started in earnest Sunday a week and a few days ago. Then a friend invited me to go ride a populaire with him, which I assumed meant a 100km, which I figured I could do without a problem, and still stay ketogenic. The day before the ride, I discovered it's a 104-miler, with modest climbing, about 6600 feet. Uh-oh, a little more challenging to stay ketogenic :-)

I took with me all the usual carb-based fuel, just in case. But I never touched it. As it turns out, what I ate for the day was: Two hours before the ride, a 3-egg omelette and four slices of bacon. At the ride start, about 1/3 cup of half and half with some coffee mixed in so I could pay for a coffee at 7-11 and get a receipt. At the half-way point, I ate an 8-ounce cheeseburger with bun and a "side salad". Another 20 miles later I bought a bag of pork rinds. During the ride I drank a total of six 24-ounce bottles of water and ate half a dozen SaltStick electrolyte pills (temperature ranged from 39 up to 73).

My energy was pretty good until about 75 miles in, when I started thinking that I was looking forward to being done. Though partly that was just worry about whether I could really sustain another 25 miles without eating carbs. As it turns out, I made it all the way without eating any more carbs for the day than the hamburger bun and (I am assuming) a bit of sugar in the salad dressing. I was able to ride a few sections hard, but I really didn't want to burn too many candles and then have to fall back on carbs, so I spent almost all of the day at 20 beats below LT (or less).

I don't think there's any way that I could have done this without the prior week of adapting to a LCHF diet.

I'll be riding the Flatbread 205km this coming Saturday, so it'll be interesting to see how that goes.

Nick

skiffrun

Oh, darn. I was thinking y'all did the Flatbread in December, and was thinking to maybe come up your way; however, I just agreed to ride the 210k "Egypt Mtn" perm with a newbie this Saturday. I think he may have to slow down a bit because I ain't gonna' pick it up any. However, the centuries that he has done have, except for one, been on or quite near the OBX, and he lives on the SE side of Raleigh, and riders on that side of town usually have a tendency to ride further south and east, towards flatter and flatter stuff. "Egypt Mtn" has the least climbing of the active north of Raleigh perms, but it ain't flat.

Maybe, repeat maybe, if I get in better cycling shape next year, I'll try to make it up your way for a brevet. But with Alan's brevets and Tony's brevets here, and Keith's brevets also being closer than your'uns, and figuring in the vagaries of schedules, ...

up on two

I've bonked a few times on the trails and a couple of them had me confused at the time but the common denominator each time was that I didn't eat properly, or at all before the ride.

With all the gels, tablets and other supplements available out there, stock up on a few and keep them handy when you ride because you never know when you or a riding buddy might need some help.

Jarrett2

OP, check out this book:

https://www.primalblueprint.com/primal-endurance/

Richard Cranium

Geez- I pretty much have given up on rewriting nutrition articles for people mixing up slang and scientific terminology in a single thread.

For the record - I'd like to post that I believe "real bonking" is when an athlete exercises so intensely that critical bodily functions are compromised. This results in a cessation of exercise and in severe cases the athlete may feel nauseous, weak and disoriented. This "real bonking" only happens when the exercise is intense enough to "outstrip" glycogen metabolism as well as diminish and draw down critical blood sugar levels.

Other slang - like "hitting the wall" and "running out of gas" mean different things to me.

Anyway these processes are often not discussed clearly because of contextual variations of terminology as well as poorly shared recognition of definitions.

This is why science journals and textbooks are difficult reads.

BikeLite

https://runnersconnect.net/running-n...fatigue-cramp/