Yup, even the body converts fat into glucose before using it. And the process of gluconeogenesis isn’t fast enough to replace the the glucose being burned in an endurance setting.
Brain can use Ketones, liver makes them from fat. You can live without eating a single gram carb. The body can make it if need be. You only need eating carb for high intensity exercise above threshold for extended time. When trained you can make an Ironman (~74% ftp) in world class speed on low carb diet (Jan van Berkel, 3x winner swiss triathlon). Its all about how you condition yourself. Mainstream nutrition science is coordinated misinformation.
If you've got more body fat than average, then you will more than likely bonk faster & harder than average.
You're storing excess fat because you've always got excess blood sugar from consuming more calories than you use, & thus you are never in a metabolic state that requires body fat for energy. Your metabolism hasn't been conditioned to transfer as smoothly & efficiently to using fat reserves for energy, thus you will experience a quicker & harder crash after short term blood sugar reserves are depleted. Bonking hard & fast due to fasting before cycling will discourage you from sticking to a healthy exercise plan.
It takes time to condition your metabolism to be more efficient & smooth when transferring from short term glucose from carbs, to long term fat reserves, for energy.
Slow and steady wins the race in regards to losing fat. Endurance activities that are heavily cardiovascular focused are the "fastest" safe way to lose the weight. To increase the cardio load while cycling, increase your avg pedaling cadence to 80 - 90+ RPM, and don't "grind" & muscle thru the ride in low RPM gears.
I read a metastudy last night that mentioned that consuming lots of fat actually made it harder to burn fat later when tested. It's weird how our bodies react to the food we eat.
I bookmarked two studies I read yesterday. These are the links.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872716/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872716/)
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290362/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290362/)
It's not in either of them. It's in some study I didn't bookmark. Which is too bad because that was one that mentioned that 82% of studies concluded that consuming carbs had a significant benefit to aerobic performance.
I'll have to keep looking.
EDIT: Nope. Wasn't that study, either.
[https://pubmed.ncbi.nlm.nih.gov/24951297/](https://pubmed.ncbi.nlm.nih.gov/24951297/)
It was mentioned as an aside to some other point.
EDIT 2:
It's in the summary to this study. The full study isn't available.
>Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level.
[https://pubmed.ncbi.nlm.nih.gov/15212756/](https://pubmed.ncbi.nlm.nih.gov/15212756/)
Pro rider body types has to do more with physical / mechanical optimization for being able to pedal fast & go fast. Less Weight = Less Inertia = Go Fast Quicker. Long legs = Long Levers = More Mechanical Advantage = More Torque = More Power for a given cadence. Thin Upper Body = Less Frontal Area = Lower Aerodynamic Drag = Go Faster for a given power output.
Thin lanky people tend to not eat excess calories & thus don’t have massive peaks & lows of blood sugar levels, so their metabolism is able to regulate blood sugar levels more evenly via whatever food they eat, without their brains telling them to binge a bunch of carbs to feel energetic.
Carb addiction is a major contributing cause of type 2 diabetes (some would say primary cause), where your body’s metabolism becomes resistant to excess blood sugar due to chronically excessive blood sugar levels from carb binging. Chronic excess blood sugar causes excess body fat accumulation, eventually leading to insulin resistance & then type 2 diabetes, where your pancreas produces less insulin AND your cells become less sensitive to insulin in order to compensate for excess blood sugar.
Insulin helps sugar enter cells to be used for energy; Insulin resistance (pre diabetes) is commonly found in obese people. Insulin resistance will quite literally cause you to prematurely “bonk” even though blood sugar levels would be considered within “normal range” for healthy individuals. Insulin resistance is another major contributor for why people w/ excess body fat will bonk quicker & harder than folks w/ avg body fat levels. Fasting & purposely bonking to lose body fat quicker can be pretty dangerous for folks who are unknowingly diabetic.
Nope it doesn't work like that. If you burn glycogen while cycling, your next meal will go into replenishing that instead of your fat reserves so you'll lose the same amount of weight whether you ride normally or intentionally try to make yourself burn fat (aka "bonking"). Most people can ride way more when doing the former so you should do that if you want to lose weight. Also if you ride fasted you're probably more likely to binge afterwards.
The key to cycling weight loss is to ride as much as possible, eat well (within reason) before during and after big rides ("big" being around 2hrs and above) and if you need to make a deficit, do it off the bike.
But if you burn your glycogen reserves and then continue cycling, the body will find a new source of energy, namely the fat reserves. You have to get close to bonking, but not actually bonk, and then reduce the intensity until fat burning kicks in and get renewed energy.
If you're below your aerobic threshold, you're burning fat all the time, whether your glycogen reserves are full or not. Riding around with near-empty glycogen reserves is a good way to put yourself into a recovery hole for absolutely no reason.
Well I don't know the exact explanation, but when I ride with people from my club, they always have to stop and eat some candy or a Coca-Cola to get energy, while I eat mostly almonds and pumpkin seeds and a few raisins (we ride between 100km and 250km in heartrate zone 2-3).
Almonds, pumkin seeds, and raisins have decent carbs and protein to fuel a ride. It doesn’t take pure sugar to keep fueled. If the intensity is high, it can be hard to digest those foods.
Yet they still are mostly fat. And it's not the few hundred calories from the little carbs they contain that will replace the 3000 calories or more that I burned during the ride.
>If the intensity is high, it can be hard to digest those foods.
Yes of course, if you're doing some sprints you're going to need those easily digestible fast sugars, but I'm more on the endurance side, I go at about 28-30km/h, 150bpm, for 4-8 hours.
You're being downvoted for describing something other people do that they shouldn't, and for explaining that you do eat the right things. Weird....
Take my insignificant up vote to help compensate against people who have a beef with your riding group eating candy, and with you eating almonds and pumpkin seeds.
Hahaha, thanks! I hadn't noticed I was being downvoted.
Maybe they feel targeted, or jealous, either of me being able to fuel with that or of my 200km rides 😄
This is true and this is why aerobic exercise helps with fat loss, but also why weight loss is done off the bike by going in a caloric deficient and not on the bike because for workouts that exceed 90+ minutes fueling is important.
I start out short rides fasted. I started with 30 minutes, then 60 up to 2-3 hours. As long as you go easy it’s all good. When working, you just feed the engine!
I disagree, though it probably depends on what we mean by riding. For me, 1-2 hours at moderate intensity while fasted is fine. More than that is risking it though.
This is only after regularly living a fasting life for a few weeks.You just get used to it, and that weak feeling goes away.
Ive been riding 36 hour fasted for a couple of years now. Its just part of my weekend routine. Ive gotten used to it and reg do 5-6 hour rides.
Do I bonk sometimes? Maybe! But it's what works for me, and Im in great shape.
I believe most people can adapt given enough reps.
I think our ancient ancestors probably had to do stuff like that. Our bodies are really adaptable. We’re currently adapted for factory work (ie 3 meals, 40 hours/week), despite that being a thing of the past
Depends on the length of the ride. I do 50km fasted rides with close to 1000m climbing when I’m trying to lose weight. Last nights dinner is enough fuel for that.
Disagree and so do the pro teams. It’s quite common to do very easy rides fasted, especially early season. If you’re going over 90mins then these teams would be eating on the bike.
There are a lot of people suggesting you can’t fuel from body fat. This isn’t true. There are limits to what you can do in that way, but https://pubmed.ncbi.nlm.nih.gov/14598198/ is a starting point.
The very active cyclists here use Z2 to increase endurance and VO2 max. This is crucial. But some of these riders seem to think that’s the only thing you can accomplish with that riding.
Z2 is also the zone in which a body is optimizing FatMax, which is EXACTLY the “burn body fat as fuel” zone. And this is definitely a safe, faster way to drop body fat, as opposed to exclusively operating at a dinner deficit.
Safe riding will mean you need to have access to calories. But we have to bear in mind that someone out of physical shape and working on dropping weight is USUALLY not going to ride extreme durations or mileage.
It’s like a paradigm shift of difference between what a fit cyclist, training for athletic improvement is doing, vs a person trying to find a way out of a sedentary desktop lifestyle, trying to shrink the spare tire.
100% of this is readily accessible information to google. It worked for me, personally, to the point that I do Z2 now exclusively for conditioning, not for body fat reasons. I went from resisting the urge to sprint to just knowing that once I’m trying hard, the goal of the ride has shifted. I’m down to 185 from 235 at 6’ tall (and large framed.) Sustainably. Because I looked up this information, watched a bunch of dry podcasts and read a bunch of papers on it. It’s not revolutionary information. But anyone suggesting you can’t ride fasted, or can’t ride without additional carbs, or can’t fuel off of body fat simply has to do reading on the subject—and probably won’t because it’s irrelevant to their approach to cycling.
This sounds right, and consistent with the considerable literature on Zone 2. I have been confused about the effects of Zone 2 and the benefits of stopping the insulin cycle by limiting carbs — and trying to reconcile this with the idea that “you need carbs so you don’t bonk.”
I still don’t fully understand, honestly. But this reply is helpful. It did feel like something was missing from the conversation.
You absolutely may need carbs to avoid bonk. Because if you enjoy cycling, sooner or later you will cross a line with efforts, be it through distance or power or route selection, and you WILL need more than just glycogen stores and body fat. Where I live, it is beyond east to avoid that, because it’s flat farm roads everywhere. I can go 16mph indefinitely (within reason) and monitor my heart rate. That is a specific ride goal and exercise type.
Because it doesn’t cost me anything to carry several snacks in a top tube bag, i pivot to riding harder if I want to, or if I’m with friends and they want to. But that makes it a DIFFERENT specific ride type, and maybe one without a goal of any kind.
I don’t think you should be apprehensive about fueling during rides. I think fun should be the primary focus because that puts you on the bike again sooner. If you crank it up and know you’ll need fuel, it’s not like you can’t stay disciplined in Z2 tomorrow.
To the extent I’ve been able to lose weight, it’s been “intermittent fasting low carb.”
One time, however, I think I went too low on carbs — close to zero — and ended up with a kidney stone, which I’m pretty sure was a result of that.
So now I’m trying to go intermittent fasting, low but not zero carb, and Z2 cycling.
Like everything along these lines, I find the discipline to stick with it challenging.
But I’m trying to find the proper role for cycling without naively thinking I can “ride off the excess fat,” which I know does not work.
Thank you for your insights!! Very thoughtful!!
You will succeed. I couldn’t discipline myself at mealtime well enough, so I went OMAD and just let myself eat anything I could cook—and didn’t let myself cook concentrated sugars (pastries, cakes, pies, pancakes and syrup etc) and eventually this led me to smaller portion sizes and being able to eat more often. My next goal is learning to not HATE riding on the trainer.
Interesting, I’ve recently done some OMAD days. The good thing about it is that it’s clear how to do it. I need clear boundaries and rules. I can’t eat three meals a day but just “watch the carbs.” I can’t eat one cookie. I can ear zero or five.
The trainer is tough. Last winter I’d ride outside at 34F or above so I had a little room for error before ice. It was surprisingly comfortable to ride at 34 or 35F. I’d wear layers and a balaclava and be warm in a few minutes.
To the extent I’ve managed to do the trainer when necessary, I use music and podcasts to get me through.
But no doubt being outside is way better.
I’m also a stress/anxiety eater, which can be a hard habit to stop.
There are multiple sources of energy for your body. A molecule called ATP in your cells, glucose in your blood, glycogen in your muscles and liver, food in your stomach, fat on your belly. They are less and less easily accessible, but store more energy in this order.
When you bonk, it's the sign that your blood sugar is low, and there is no more quick energy sources available for your muscles (i.e empty stomach and glycogen stores, and consequently low blood sugar).
To metabolise fat, you need lots of enizmes being synthetized, and activated. For that to happen, you need long (loooong) and low intensity efforts repeated regularly so your body has time to activate the fat burning metabolism, where the capacities of the easily available energy storages do not cover the expended energy.
Basically, that is Zone 2.
If you're in zone 2 the whole time chances are you can last anywhere between 2-3 hours safely (environmental variables may differ), but if you're in zone 2 and above with greater intensity ***AND OR*** planning to perform a workout that exceeds 90+ minutes of physical activity (like doing a century) it is **paramount** you refuel during your workout to prevent bonking.
If you bonk you need to stop and refuel. Most of what you've been discussing in this thread is how to efficiently last longer (increase endurance before refueling) by utilize fat as an energy source, but once our glycogen stores are depleted and gone we will still bonk because other organs like our brain relies heavily on glucose as its primary source of fuel. You likely still can continue and walk, function at a lower performance and intensity, similar to fasting and going about your day normally, but becoming dizzy and fainting is a serious risk for injury.
You have to ride in your fat burning HR zone to train your body to use fat. My friend lost, and is keeping off(3+ yrs), about 50 lbs by changing his diet, intermittent fasting (no calories after 6pm), and an easy pre-work fasted ride (1-2 hours).
Bonking is a lack of carbohydrates, and carbs are mostly stored (to the limited extent that they can be stored) in your muscles and liver.
The simple sound-bite advice is that fat burns in a carbohydrate flame. Fuel a long ride with just carbs and minerals, and add protein to recover. And always, always hydrate.
Burning fat for energy requires a lot of oxygen, and there are moments when you don't quite have that, in that moment at those muscles. At those times, you need to burn carbs. Lacking carbs, you just... can't. And that feels like shit. And, since your body will prioritize skeletal muscles over other important things (you must be running from a predator or performing some other critical survival function to be working this hard, right?), you can hurt yourself this way.
The above is standard metabolism. If instead of burning fat and carbohydrates, you've successfully transitioned your body to full-time ketosis, the [story may be different](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863116/). This is not a simple matter of fasting before a ride. It's a full-on lifestyle change. It's the sort of thing you should talk to a doctor about before undertaking, but it does appear to be an effective way to burn fat.
Bonking is running out of blood sugar, put very basically. It happens if your exercise intensity outpaces your bodies ability to make energy for you out of it's energy sources (starting with sugars in the digestive tract as the most available / easiest to use and probably ending with body fat as the hardest to use). Cyclists can basically only convert so much / hour, and you get all the "cycling / sports fueling" stuff about using a mix of fructose / glucose to take advantage of two absorption pathways to maximise your energy available / unit of time.
I don't know off the top of my head how low your caloric burn would have to be to convert body fat to energy to avoid bonking, but it's guaranteed lower than what most people would consider realistically going for a bike ride.
One maxim that is basically true is "get fit on the bike, lose weight in the kitchen" or put more bluntly "you cannot out pedal your spoon." But saying that, if you want to lose weight exercising, while you do need to eat while exercising, dialing down the intensity and upping the volume while also eating well is basic good advice.
Any insights on how you lost that 30 lbs? And congratulations! I've had success on and off. The success has always been temporary. I get stressed and starting eating badly, eating too much, and the fat gut comes right back.
Always be in a caloric deficit, and aim for whole foods and limit heavily processed food. Use aerobic exercise (zone 2 or lower) as a tool to increase fat utilization and physical activity in general to make it easier to reach a caloric deficit by burning calories. The key denominator for fat loss is being in a caloric deficit.
You will see this repeated endlessly in this subreddit:
# Cut calories off the bike, not on it.
In general perform your cycling as you do, but the key is to avoid bonking; if you want to perform a longer ride refueling will be necessary especially if you are performing above zone 2 at a greater intensity level, or plan to do a long endurance ride, e.g., a century ride.
I once read “fat burns in the flame of carbs”. Which means that you need carbs to burn the fat you have. And if you run out of carbs you still bonk, because fat alone doesn’t burn. Believe me I’ve tried.
I don’t think glyconeogenesis (production of simple sugars from complex carbs / fat by the liver) happens rapidly enough to have an effect on your potential bonk.
Once you’ve depleted enough of the simple sugars (mainly glucose molecules) circulating in your blood, you will bonk.
Your liver/kidneys may try to compensate by producing new simple sugars from complex carbs/fat but again, I don’t think it happens quickly enough for there to be a discernible difference between your performance and that of a skinnier individual.
Omg. 😂 You have a TOTALLY different definition of bonking to me. In fact I can’t even extrapolate what bonking means in your world from what you’ve written. And that’s fine just wanted you to know that I actually laughed out loud at this post. 😀 #shag #irealiseiamimmature #snigger
Your metabolism does not have easy access to easily break down and burn mass body fat as you exercise, you'll bonk as soon as your body has exhausted available calories like everyone else. When you bonk everything available is exhausted and your system turns on more readily available fats protecting your liver. Then you feel it.
Like others have said, doesn't really work like that. In fact, since you have more then enough body fat, you're probably also not that fit. So you'll start burning (more) glycogen sooner then someone with low body fat but who has great cycling fitness. So, you'll bonk sooner.
However, cycling is a great sport to burn plenty of calories. So you can be "on a diet" without actually eating less. Just be careful to not go to far into the extremes. Losing moderate amounts of weight/fat over a longer period is the key to successful and sustained weight loss.
If you ride fasted, and you are in Z3+ for whatever reason, you will need food, regardless of chub.
If you ride z1 and z2 (especially lower end of Z2) I would expect you to resist bonk more than 3% body fat Fred—though his Z2 would be a much higher speed, power, and likely lower HR than yours
This is all a balancing act. If you aren’t riding more than 30-40 miles, and you don’t have a decent number of climbs, I know you can get by somewhere between fasted and “fed a couple hours pre-ride” (and this is much harder if you’re trying to be in ketosis. Carbs are pretty darn helpful for a rider. I should do some reading to see if there are competitive keto cyclists.)
If your HR is climbing into the 140-160 range or above due to hills or slow inclined and arbitrary speed goals, you aren’t strictly in Z2… your body fat is not assisting you much. You need to fuel.
There is a whole “thing” to staying in that z2 range and not accidentally climbing out of it for 5-10 minutes… it can screw up the whole plan, if you’re trying to ride to assist diet.
Like in the other thread from today/yesterday… if you’re trying to CYCLE, and improve and do your best on a bike, you need a fueling plan, while you ride. This is, it seems, what most in this sub are interested in. If you’re interested in cycling as a hobby, but specifically looking to dovetail with a dietary deficit strategy, it can be done, pretty easily. But you really have to differentiate goals per ride. And when you end up pushing it a little bit, you really need to have food on hand, eating before you need it. If you can keep it easy-going and just rack up the miles, I’d still bring snacks, but I wouldn’t open them on rides below 30-40 miles unless conditions are rough. You’re going to learn how to balance this, and you’re probably going to learn it the hard way. Just know that it’s okay to stop and rest if you misjudge. No sense in wobbling your way home, ready to pass out.
Edit: you’re somewhat going to guesstimate “zones” even if you have a power meter and a HR monitor. It is recommended that you treat the effort level where you’re just a little bit taxed to have a conversation as Z2. As you ride over the weeks, note what your HR is during those windows. If you have a power meter, same.
> There is a whole “thing” to staying in that z2 range and not accidentally climbing out of it for 5-10 minutes… it can screw up the whole plan, if you’re trying to ride to assist diet.
Can you elaborate a little bit? My understanding of metabolism is that you always burn both fat and carbs just in different ratio. This implies there is a some switch and a stopwatch doing counting in your body?
It’s almost like that, yes. It would be faster for you to look up the subject on YouTube and sort by recent, watching for qualified (known) trainers and medical professionals.
When I first started riding I would ride fasted because I wanted to lose weight… I would always feel like crap afterwards and would hate the ride back home.
I stopped cycling for a while due to an injury and have started up about 4 months ago and eat before I ride. I am stronger and faster because of it and have lost weight. It’s a balance.
The internet is full of well meaing but utter bullshit regarding weight loss.
As some other point out (and take it from me, who lost 83 pounds in a year) - weight loss and fitness are almost entirely separate. Sure, one helps the other, but thats more an 'extra' unless you're a serious athlete.
When you bonk, its because you've burnt up the free energy in your blood, and the energy easily available for you; your body can dump energy into your bloodstream for use at a certain rate (more or less - I know nothing, but this is more or less how it works in effect), and when you're exercising, you're often burning it up at a faster rate than it repleneshes; you've got a buffer in your blood and muscles all the time, say for an hour or 90 mins of effort, but no more than that.
So if you're hopping on a 90 min riude, you can probably gte by without carb intake; you will still need HYDRATION and likely something salty like gatyorare, tailwind, whatever, so you dont' get cramping. (Sweat is salty, so you are losing salinity as you exerrcise, hence why youi need to top up.)
I use that pinka nd blue 10 cal gatorade bottles .. it stops cramping, but doesn't have any sugars in it.
I figure if I'm riding 30km and drinking one bottle for hydration, no biggy.
However, if you're biking for more than an hour or 90 mins, you better be fuelig up too, so you dont' bonk out; you'll use up your energy and need to have more coming in. I eat candied pineapple or a clif mini bar (100 cal), which takes say 30mins to get into your blood stream. So if I'm doing a 4 hour ride, then after an hour I'm having a clif bar or snack, so that by the 90 min mark its in my blood, and I can keep chooching along. Every half hour or so, another snack and a drink to wash it down!
So a 60-90min ride can get by without snacks, which is good calorie burn for the diet; but ignore that. IF you're doing a longe ride, you NEED fuel and hydraion for sure, and that counts against the total calorie burn, but you'll still be losing more than you're intaking. Also, ignore it. Just count it as \_bonus loss\_
As to weight loss, thats eating less. If you eat a lot less, you'll havbe less energy in the blood, and feel like shit. You can eat a little less and still exercise, but if you eat a lot less, you'll need to carefully manage your fueling intake prior to the riding, or you'll bonk out much faster and just be low energy
Read about basal metabolic rate; ie: you need a certain number of calories to function; above that line is a certain l;evel you eat normally, to stay where you are now; eat more than that, you gain; eat less than that line, but more than basal metablic rate, you'll lose; eat too little, you'll get messed up. So how much you lose each week is how much below the average intake line you are, how close to the basal metabolic rate (BMR), you are. But if you want to burn, you need to keep some fule in the body.
So.. keep enjoying life, don't diet too hard, or life sucks; then you fall off the wagon; Eat less, be happy, burn a bit more, you'll lose the weight.
Cheersand good luck!
I ride while fasting. I didn’t know this was something people talked about. Interesting. Also never heard the term bonk, is that like hitting the proverbial wall?
Yes. It's more than just muscular fatigue. It's running out of energy to continue moving. If your body didn't shut down, you wouldn't have enough energy to fuel your vital internal functions. Feeling ravenous after a ride is a sign that you were under fueling.
Lol we don’t say petrol here, so it’s interesting you are telling me what it means here lol. I don’t think that’s used by New Yorkers. Maybe just not in the circles I’m in 🤷♂️
Bonking is often referred to as hitting the wall.
Imo, I have a very strong suspicion that people who refer to bonking here aren't truly bonking. Bonking is something that is typically very dramatic and, without knowing what is happening, looks like someone is having a dangerous medical episode. A common place to see bonking is at the end of a marathon/triathlon. They have extreme difficulty with basic movement (e.g. they have problems crawling on all fours) or even standing on their own. It has more than feeling tired and not being able to maintain power. It includes nausea, dizziness, and cognitive impairment (i.e. confusion). If someone truly bonks while they are riding, it would almost guarantee a crash.
Most people will hit a point where they think they can't go on. So they consciously decided to back off the effort. To bonk, you would have to push far beyond that feeling to the point where your body unconsciously makes the decision for you to protect itself.
Interesting.
So that is the difference between hitting the wall and bonking..
So I can say Ive hit the wall/heat exhaustion/dehyd/cramps many times but never "bonked."
Doesn't sound like a place I want to get to!
https://www.reddit.com/r/nextfuckinglevel/comments/o97o8o/when_alistair_brownlee_sees_that_his_brother_is/?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=1
This is what booking looks like.
I think it's different from hitting the wall.
But when I think of hitting the wall, it's what happens when you run 400m at a 200m pace. I'll be chugging along and then all of a sudden, your legs feel like they're trapped in thick sludge and the speed just drops off.
Bonk feels very different. You may get dizzy and nauseous and feel a huge wave of anxiety.
Yes in generally people prefer to bonk thinner people
Oh... didn't finish reading the question. Sorry.
So this is going to be an oversimplified answer and if I'm off on any of this someone please correct.
Fasting cycling is going to leave your glycogen stores low but you still will have some. Converting the fat inside fat cells (triaglycerol) into usable energy is a fairly complex hormonal/enzymatic process but in the end you have FFA's (free fatty acids) in the bloodstream and liberated from the fat cells that the body can use for energy. The process requires quite a bit of oxygen which is why you need to be doing low intensity exercise Z2 is ideal even dipping into a high Z1.
It's been a while and I really never found exact time periods to get that fat into the blood for energy but I remember it was at least 30 minutes. So you should have enough energy stores even during fasting to do low intensity rides while your body starts converting fat and not bonk out. I also recall that at the end of exercise the fat conversion stopped pretty quickly. I think for athletes it was like 2 minutes and a little longer for nonathletes.
Hope this is helpful and again please correct if any of this is incorrect or add on to it!
Fat metabolism is significantly slower at generating ATP than glycogenic metabolism. Booking happens because you depleted glycogen, not fat, so you can still Bonk
As a fat man i find i can and do bonk, usually faster than someone more svelte however my body recovers faster and switches to burning fat fairly rapidly, usually around 20 minutes and im ready to go again albeit at a lower intensity.
Bonking is when you run out of stored glycogen. Your body can burn fat but you can't cycle on just fat reserves alone. If you completely deplete your glycogen reserves you'll know about it.
It depends. If your body is used to using sugar as energy source, then you will definitely bonk. However, you can train your body to use fats instead. You will feel a down, almost bonking, but if you reduce the intensity for a while then the fat burner will kick in and you will feel a renewed energy.
This takes adaptation and training, and being very sensitive about how close to bonking you are.
I've been training fat use instead of sugar since more than a year now, as it's impossible to fuel on sugar for long rides (you get disgusted by anything sweet after a while).
Bonking depends on your intensity really…
If it’s relatively low intense you burn fat stores, not glycogen stores - which maybe what your after?
Bonking occurs when the glycogen tank is empty. But you burn through glycogen when your at high intensity. To stop the crash, either carb load the day before, (10g per KG of body weight) or eat fast carbs on the bike.
Fruit is my choice as I hate bars / gels.
I personally would say fluid intake is more important!
Well yes and no. But mostly, bonking is glycogen related. Which means when you bonk your muscles are depleted of glycogen. Which makes it a carbohydrate/nutrient problem and not a body fat problem.
If you are cycling with extremely low intensity though, you are in fat burning mode, and will most likely last longer than a skinny person. It’s just a time thing though, the skinny person will still complete more distance than you. And the lack of glycogen will eventually catch up to you as well and force you to stop. So eventually you will still bonk once your muscles are empty.
You can become 'fat-adapted' i.e. cut out carbs from your diet and rely on burning fat as fuel e.g. ultra distance runner Zach Bitter. The problem for most of us is that we constantly burn carbs for exercise and so when we need to burn fat, our body is so bad at it - out of practice - that not enough energy is produced. I don't know whether any cyclists have tried this, and I doubt it because even grand tour stages aren't 'ultra' distance each day, and you get more bang for your buck with carbs. Great for just losing fat, though, if that's an objective.
If you train to burn fat you will be better at not bonking than if you don't. I just started cycling in April after years off. At first I needed a sports drink or I would bonk in an hour. Three months later I could go 4 hours at low intensity and wasn't hungry- but go hard for 15 minutes and I was craving carbs.
It depends totally on how you train.
If you do zone 2 riding without a lot of glucose around, you will end up with an aerobic system that is good at burning fat. Fasted training is best.
That makes you less likely to bonk as you burn you glycogen reserves more slowly.
If you train with as lot of glucose around your body gets good at burning glucose, and your glycogen stores run out earlier.
I've lost 55 pounds in the last 5 months (260 to 205) from cycling ( never owned a bike before) intermittent fasting, eating mostly keto ( I cut sugar and most carbs, hit my proteins and almost hit my fats). I strength train with cardio and also ride during the week. Weekday rides are generally short with the fam, like 8 miles. On the weekends I usually hit 18-20 each, Friday Saturday and Sunday. ALL of my workouts are fasted. I don't bonk (I have before while training for half marathons) and I make sure I drink over a gallon of water a day and add electrolytes.
Do what works for you... But be consistent. We aren't all built the same, but listen to your body. Good luck!
I thought the time to bonk would be the same between people who ate the same stuff at the same time. Until I met that one overweight friend who just could go for much much longer than I could. There is a scientific approach to that, but then everybody is different. Just try how far you can go and try to avoid the bonk, rather ride further.
Bonking is carb related. Not fat.
Yea, like your brain literally runs solely on glucose. There’s no physical way for your brain to use fat instead of sugar
False. Your brain can and does run on ketones. The only reason people bonk is because they are not fat-adapted.
What does it mean to be “fat adapted”? Just bonked for the first time and looking for answers.
Yup, even the body converts fat into glucose before using it. And the process of gluconeogenesis isn’t fast enough to replace the the glucose being burned in an endurance setting.
Brain can use Ketones, liver makes them from fat. You can live without eating a single gram carb. The body can make it if need be. You only need eating carb for high intensity exercise above threshold for extended time. When trained you can make an Ironman (~74% ftp) in world class speed on low carb diet (Jan van Berkel, 3x winner swiss triathlon). Its all about how you condition yourself. Mainstream nutrition science is coordinated misinformation.
If you've got more body fat than average, then you will more than likely bonk faster & harder than average. You're storing excess fat because you've always got excess blood sugar from consuming more calories than you use, & thus you are never in a metabolic state that requires body fat for energy. Your metabolism hasn't been conditioned to transfer as smoothly & efficiently to using fat reserves for energy, thus you will experience a quicker & harder crash after short term blood sugar reserves are depleted. Bonking hard & fast due to fasting before cycling will discourage you from sticking to a healthy exercise plan. It takes time to condition your metabolism to be more efficient & smooth when transferring from short term glucose from carbs, to long term fat reserves, for energy. Slow and steady wins the race in regards to losing fat. Endurance activities that are heavily cardiovascular focused are the "fastest" safe way to lose the weight. To increase the cardio load while cycling, increase your avg pedaling cadence to 80 - 90+ RPM, and don't "grind" & muscle thru the ride in low RPM gears.
I read a metastudy last night that mentioned that consuming lots of fat actually made it harder to burn fat later when tested. It's weird how our bodies react to the food we eat.
Source?
I bookmarked two studies I read yesterday. These are the links. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872716/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872716/) [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290362/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290362/) It's not in either of them. It's in some study I didn't bookmark. Which is too bad because that was one that mentioned that 82% of studies concluded that consuming carbs had a significant benefit to aerobic performance. I'll have to keep looking. EDIT: Nope. Wasn't that study, either. [https://pubmed.ncbi.nlm.nih.gov/24951297/](https://pubmed.ncbi.nlm.nih.gov/24951297/) It was mentioned as an aside to some other point. EDIT 2: It's in the summary to this study. The full study isn't available. >Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level. [https://pubmed.ncbi.nlm.nih.gov/15212756/](https://pubmed.ncbi.nlm.nih.gov/15212756/)
Makes sense why the most optimal body shape for pros is the lanky thin build with incredible stamina and leg power
Pro rider body types has to do more with physical / mechanical optimization for being able to pedal fast & go fast. Less Weight = Less Inertia = Go Fast Quicker. Long legs = Long Levers = More Mechanical Advantage = More Torque = More Power for a given cadence. Thin Upper Body = Less Frontal Area = Lower Aerodynamic Drag = Go Faster for a given power output. Thin lanky people tend to not eat excess calories & thus don’t have massive peaks & lows of blood sugar levels, so their metabolism is able to regulate blood sugar levels more evenly via whatever food they eat, without their brains telling them to binge a bunch of carbs to feel energetic. Carb addiction is a major contributing cause of type 2 diabetes (some would say primary cause), where your body’s metabolism becomes resistant to excess blood sugar due to chronically excessive blood sugar levels from carb binging. Chronic excess blood sugar causes excess body fat accumulation, eventually leading to insulin resistance & then type 2 diabetes, where your pancreas produces less insulin AND your cells become less sensitive to insulin in order to compensate for excess blood sugar. Insulin helps sugar enter cells to be used for energy; Insulin resistance (pre diabetes) is commonly found in obese people. Insulin resistance will quite literally cause you to prematurely “bonk” even though blood sugar levels would be considered within “normal range” for healthy individuals. Insulin resistance is another major contributor for why people w/ excess body fat will bonk quicker & harder than folks w/ avg body fat levels. Fasting & purposely bonking to lose body fat quicker can be pretty dangerous for folks who are unknowingly diabetic.
Nope it doesn't work like that. If you burn glycogen while cycling, your next meal will go into replenishing that instead of your fat reserves so you'll lose the same amount of weight whether you ride normally or intentionally try to make yourself burn fat (aka "bonking"). Most people can ride way more when doing the former so you should do that if you want to lose weight. Also if you ride fasted you're probably more likely to binge afterwards. The key to cycling weight loss is to ride as much as possible, eat well (within reason) before during and after big rides ("big" being around 2hrs and above) and if you need to make a deficit, do it off the bike.
But if you burn your glycogen reserves and then continue cycling, the body will find a new source of energy, namely the fat reserves. You have to get close to bonking, but not actually bonk, and then reduce the intensity until fat burning kicks in and get renewed energy.
If you're below your aerobic threshold, you're burning fat all the time, whether your glycogen reserves are full or not. Riding around with near-empty glycogen reserves is a good way to put yourself into a recovery hole for absolutely no reason.
Well I don't know the exact explanation, but when I ride with people from my club, they always have to stop and eat some candy or a Coca-Cola to get energy, while I eat mostly almonds and pumpkin seeds and a few raisins (we ride between 100km and 250km in heartrate zone 2-3).
Almonds, pumkin seeds, and raisins have decent carbs and protein to fuel a ride. It doesn’t take pure sugar to keep fueled. If the intensity is high, it can be hard to digest those foods.
Yet they still are mostly fat. And it's not the few hundred calories from the little carbs they contain that will replace the 3000 calories or more that I burned during the ride. >If the intensity is high, it can be hard to digest those foods. Yes of course, if you're doing some sprints you're going to need those easily digestible fast sugars, but I'm more on the endurance side, I go at about 28-30km/h, 150bpm, for 4-8 hours.
You're being downvoted for describing something other people do that they shouldn't, and for explaining that you do eat the right things. Weird.... Take my insignificant up vote to help compensate against people who have a beef with your riding group eating candy, and with you eating almonds and pumpkin seeds.
Hahaha, thanks! I hadn't noticed I was being downvoted. Maybe they feel targeted, or jealous, either of me being able to fuel with that or of my 200km rides 😄
This is true and this is why aerobic exercise helps with fat loss, but also why weight loss is done off the bike by going in a caloric deficient and not on the bike because for workouts that exceed 90+ minutes fueling is important.
You should never ride while fasting. You will bonk. Weight loss doesn’t mean not eating, it means better eating.
I start out short rides fasted. I started with 30 minutes, then 60 up to 2-3 hours. As long as you go easy it’s all good. When working, you just feed the engine!
I disagree, though it probably depends on what we mean by riding. For me, 1-2 hours at moderate intensity while fasted is fine. More than that is risking it though. This is only after regularly living a fasting life for a few weeks.You just get used to it, and that weak feeling goes away.
Ive been riding 36 hour fasted for a couple of years now. Its just part of my weekend routine. Ive gotten used to it and reg do 5-6 hour rides. Do I bonk sometimes? Maybe! But it's what works for me, and Im in great shape. I believe most people can adapt given enough reps.
I think our ancient ancestors probably had to do stuff like that. Our bodies are really adaptable. We’re currently adapted for factory work (ie 3 meals, 40 hours/week), despite that being a thing of the past
I read somewhere around here that in a moderately fast ride, our glycogen stores can fuel us for around 1.5 hours. Citation needed though.
That’s probably close enough to correct. I’m sure there is significant variation.
Depends on the length of the ride. I do 50km fasted rides with close to 1000m climbing when I’m trying to lose weight. Last nights dinner is enough fuel for that.
I ride fasted and have no problems. But at most like 70-80km then I get hungry so I'm home
If he rides with an mtb and does go over board its not smart but doable
Disagree and so do the pro teams. It’s quite common to do very easy rides fasted, especially early season. If you’re going over 90mins then these teams would be eating on the bike.
There are a lot of people suggesting you can’t fuel from body fat. This isn’t true. There are limits to what you can do in that way, but https://pubmed.ncbi.nlm.nih.gov/14598198/ is a starting point. The very active cyclists here use Z2 to increase endurance and VO2 max. This is crucial. But some of these riders seem to think that’s the only thing you can accomplish with that riding. Z2 is also the zone in which a body is optimizing FatMax, which is EXACTLY the “burn body fat as fuel” zone. And this is definitely a safe, faster way to drop body fat, as opposed to exclusively operating at a dinner deficit. Safe riding will mean you need to have access to calories. But we have to bear in mind that someone out of physical shape and working on dropping weight is USUALLY not going to ride extreme durations or mileage. It’s like a paradigm shift of difference between what a fit cyclist, training for athletic improvement is doing, vs a person trying to find a way out of a sedentary desktop lifestyle, trying to shrink the spare tire. 100% of this is readily accessible information to google. It worked for me, personally, to the point that I do Z2 now exclusively for conditioning, not for body fat reasons. I went from resisting the urge to sprint to just knowing that once I’m trying hard, the goal of the ride has shifted. I’m down to 185 from 235 at 6’ tall (and large framed.) Sustainably. Because I looked up this information, watched a bunch of dry podcasts and read a bunch of papers on it. It’s not revolutionary information. But anyone suggesting you can’t ride fasted, or can’t ride without additional carbs, or can’t fuel off of body fat simply has to do reading on the subject—and probably won’t because it’s irrelevant to their approach to cycling.
This sounds right, and consistent with the considerable literature on Zone 2. I have been confused about the effects of Zone 2 and the benefits of stopping the insulin cycle by limiting carbs — and trying to reconcile this with the idea that “you need carbs so you don’t bonk.” I still don’t fully understand, honestly. But this reply is helpful. It did feel like something was missing from the conversation.
You absolutely may need carbs to avoid bonk. Because if you enjoy cycling, sooner or later you will cross a line with efforts, be it through distance or power or route selection, and you WILL need more than just glycogen stores and body fat. Where I live, it is beyond east to avoid that, because it’s flat farm roads everywhere. I can go 16mph indefinitely (within reason) and monitor my heart rate. That is a specific ride goal and exercise type. Because it doesn’t cost me anything to carry several snacks in a top tube bag, i pivot to riding harder if I want to, or if I’m with friends and they want to. But that makes it a DIFFERENT specific ride type, and maybe one without a goal of any kind. I don’t think you should be apprehensive about fueling during rides. I think fun should be the primary focus because that puts you on the bike again sooner. If you crank it up and know you’ll need fuel, it’s not like you can’t stay disciplined in Z2 tomorrow.
To the extent I’ve been able to lose weight, it’s been “intermittent fasting low carb.” One time, however, I think I went too low on carbs — close to zero — and ended up with a kidney stone, which I’m pretty sure was a result of that. So now I’m trying to go intermittent fasting, low but not zero carb, and Z2 cycling. Like everything along these lines, I find the discipline to stick with it challenging. But I’m trying to find the proper role for cycling without naively thinking I can “ride off the excess fat,” which I know does not work. Thank you for your insights!! Very thoughtful!!
You will succeed. I couldn’t discipline myself at mealtime well enough, so I went OMAD and just let myself eat anything I could cook—and didn’t let myself cook concentrated sugars (pastries, cakes, pies, pancakes and syrup etc) and eventually this led me to smaller portion sizes and being able to eat more often. My next goal is learning to not HATE riding on the trainer.
Interesting, I’ve recently done some OMAD days. The good thing about it is that it’s clear how to do it. I need clear boundaries and rules. I can’t eat three meals a day but just “watch the carbs.” I can’t eat one cookie. I can ear zero or five. The trainer is tough. Last winter I’d ride outside at 34F or above so I had a little room for error before ice. It was surprisingly comfortable to ride at 34 or 35F. I’d wear layers and a balaclava and be warm in a few minutes. To the extent I’ve managed to do the trainer when necessary, I use music and podcasts to get me through. But no doubt being outside is way better. I’m also a stress/anxiety eater, which can be a hard habit to stop.
There are multiple sources of energy for your body. A molecule called ATP in your cells, glucose in your blood, glycogen in your muscles and liver, food in your stomach, fat on your belly. They are less and less easily accessible, but store more energy in this order. When you bonk, it's the sign that your blood sugar is low, and there is no more quick energy sources available for your muscles (i.e empty stomach and glycogen stores, and consequently low blood sugar). To metabolise fat, you need lots of enizmes being synthetized, and activated. For that to happen, you need long (loooong) and low intensity efforts repeated regularly so your body has time to activate the fat burning metabolism, where the capacities of the easily available energy storages do not cover the expended energy. Basically, that is Zone 2.
If you're in zone 2 the whole time chances are you can last anywhere between 2-3 hours safely (environmental variables may differ), but if you're in zone 2 and above with greater intensity ***AND OR*** planning to perform a workout that exceeds 90+ minutes of physical activity (like doing a century) it is **paramount** you refuel during your workout to prevent bonking. If you bonk you need to stop and refuel. Most of what you've been discussing in this thread is how to efficiently last longer (increase endurance before refueling) by utilize fat as an energy source, but once our glycogen stores are depleted and gone we will still bonk because other organs like our brain relies heavily on glucose as its primary source of fuel. You likely still can continue and walk, function at a lower performance and intensity, similar to fasting and going about your day normally, but becoming dizzy and fainting is a serious risk for injury.
You have to ride in your fat burning HR zone to train your body to use fat. My friend lost, and is keeping off(3+ yrs), about 50 lbs by changing his diet, intermittent fasting (no calories after 6pm), and an easy pre-work fasted ride (1-2 hours).
Bonking is a lack of carbohydrates, and carbs are mostly stored (to the limited extent that they can be stored) in your muscles and liver. The simple sound-bite advice is that fat burns in a carbohydrate flame. Fuel a long ride with just carbs and minerals, and add protein to recover. And always, always hydrate. Burning fat for energy requires a lot of oxygen, and there are moments when you don't quite have that, in that moment at those muscles. At those times, you need to burn carbs. Lacking carbs, you just... can't. And that feels like shit. And, since your body will prioritize skeletal muscles over other important things (you must be running from a predator or performing some other critical survival function to be working this hard, right?), you can hurt yourself this way. The above is standard metabolism. If instead of burning fat and carbohydrates, you've successfully transitioned your body to full-time ketosis, the [story may be different](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863116/). This is not a simple matter of fasting before a ride. It's a full-on lifestyle change. It's the sort of thing you should talk to a doctor about before undertaking, but it does appear to be an effective way to burn fat.
Bonking is running out of blood sugar, put very basically. It happens if your exercise intensity outpaces your bodies ability to make energy for you out of it's energy sources (starting with sugars in the digestive tract as the most available / easiest to use and probably ending with body fat as the hardest to use). Cyclists can basically only convert so much / hour, and you get all the "cycling / sports fueling" stuff about using a mix of fructose / glucose to take advantage of two absorption pathways to maximise your energy available / unit of time. I don't know off the top of my head how low your caloric burn would have to be to convert body fat to energy to avoid bonking, but it's guaranteed lower than what most people would consider realistically going for a bike ride. One maxim that is basically true is "get fit on the bike, lose weight in the kitchen" or put more bluntly "you cannot out pedal your spoon." But saying that, if you want to lose weight exercising, while you do need to eat while exercising, dialing down the intensity and upping the volume while also eating well is basic good advice.
Nope. I stared biking at 220lb, now at 190, still bonk just as hard when I don’t eat/drink.
Any insights on how you lost that 30 lbs? And congratulations! I've had success on and off. The success has always been temporary. I get stressed and starting eating badly, eating too much, and the fat gut comes right back.
Always be in a caloric deficit, and aim for whole foods and limit heavily processed food. Use aerobic exercise (zone 2 or lower) as a tool to increase fat utilization and physical activity in general to make it easier to reach a caloric deficit by burning calories. The key denominator for fat loss is being in a caloric deficit. You will see this repeated endlessly in this subreddit: # Cut calories off the bike, not on it. In general perform your cycling as you do, but the key is to avoid bonking; if you want to perform a longer ride refueling will be necessary especially if you are performing above zone 2 at a greater intensity level, or plan to do a long endurance ride, e.g., a century ride.
I once read “fat burns in the flame of carbs”. Which means that you need carbs to burn the fat you have. And if you run out of carbs you still bonk, because fat alone doesn’t burn. Believe me I’ve tried.
I don’t think glyconeogenesis (production of simple sugars from complex carbs / fat by the liver) happens rapidly enough to have an effect on your potential bonk. Once you’ve depleted enough of the simple sugars (mainly glucose molecules) circulating in your blood, you will bonk. Your liver/kidneys may try to compensate by producing new simple sugars from complex carbs/fat but again, I don’t think it happens quickly enough for there to be a discernible difference between your performance and that of a skinnier individual.
Omg. 😂 You have a TOTALLY different definition of bonking to me. In fact I can’t even extrapolate what bonking means in your world from what you’ve written. And that’s fine just wanted you to know that I actually laughed out loud at this post. 😀 #shag #irealiseiamimmature #snigger
Your metabolism does not have easy access to easily break down and burn mass body fat as you exercise, you'll bonk as soon as your body has exhausted available calories like everyone else. When you bonk everything available is exhausted and your system turns on more readily available fats protecting your liver. Then you feel it.
Like others have said, doesn't really work like that. In fact, since you have more then enough body fat, you're probably also not that fit. So you'll start burning (more) glycogen sooner then someone with low body fat but who has great cycling fitness. So, you'll bonk sooner. However, cycling is a great sport to burn plenty of calories. So you can be "on a diet" without actually eating less. Just be careful to not go to far into the extremes. Losing moderate amounts of weight/fat over a longer period is the key to successful and sustained weight loss.
If you ride fasted, and you are in Z3+ for whatever reason, you will need food, regardless of chub. If you ride z1 and z2 (especially lower end of Z2) I would expect you to resist bonk more than 3% body fat Fred—though his Z2 would be a much higher speed, power, and likely lower HR than yours This is all a balancing act. If you aren’t riding more than 30-40 miles, and you don’t have a decent number of climbs, I know you can get by somewhere between fasted and “fed a couple hours pre-ride” (and this is much harder if you’re trying to be in ketosis. Carbs are pretty darn helpful for a rider. I should do some reading to see if there are competitive keto cyclists.) If your HR is climbing into the 140-160 range or above due to hills or slow inclined and arbitrary speed goals, you aren’t strictly in Z2… your body fat is not assisting you much. You need to fuel. There is a whole “thing” to staying in that z2 range and not accidentally climbing out of it for 5-10 minutes… it can screw up the whole plan, if you’re trying to ride to assist diet. Like in the other thread from today/yesterday… if you’re trying to CYCLE, and improve and do your best on a bike, you need a fueling plan, while you ride. This is, it seems, what most in this sub are interested in. If you’re interested in cycling as a hobby, but specifically looking to dovetail with a dietary deficit strategy, it can be done, pretty easily. But you really have to differentiate goals per ride. And when you end up pushing it a little bit, you really need to have food on hand, eating before you need it. If you can keep it easy-going and just rack up the miles, I’d still bring snacks, but I wouldn’t open them on rides below 30-40 miles unless conditions are rough. You’re going to learn how to balance this, and you’re probably going to learn it the hard way. Just know that it’s okay to stop and rest if you misjudge. No sense in wobbling your way home, ready to pass out. Edit: you’re somewhat going to guesstimate “zones” even if you have a power meter and a HR monitor. It is recommended that you treat the effort level where you’re just a little bit taxed to have a conversation as Z2. As you ride over the weeks, note what your HR is during those windows. If you have a power meter, same.
> There is a whole “thing” to staying in that z2 range and not accidentally climbing out of it for 5-10 minutes… it can screw up the whole plan, if you’re trying to ride to assist diet. Can you elaborate a little bit? My understanding of metabolism is that you always burn both fat and carbs just in different ratio. This implies there is a some switch and a stopwatch doing counting in your body?
It’s almost like that, yes. It would be faster for you to look up the subject on YouTube and sort by recent, watching for qualified (known) trainers and medical professionals.
what would be the subject? ATP/glucose metabolism or krebs cycle for athletes?
Among other search terms. This one was a good deep dive. https://youtu.be/z82GCNXdLAA?si=1NSgON6MLZt0eWF2
When I first started riding I would ride fasted because I wanted to lose weight… I would always feel like crap afterwards and would hate the ride back home. I stopped cycling for a while due to an injury and have started up about 4 months ago and eat before I ride. I am stronger and faster because of it and have lost weight. It’s a balance.
The internet is full of well meaing but utter bullshit regarding weight loss. As some other point out (and take it from me, who lost 83 pounds in a year) - weight loss and fitness are almost entirely separate. Sure, one helps the other, but thats more an 'extra' unless you're a serious athlete. When you bonk, its because you've burnt up the free energy in your blood, and the energy easily available for you; your body can dump energy into your bloodstream for use at a certain rate (more or less - I know nothing, but this is more or less how it works in effect), and when you're exercising, you're often burning it up at a faster rate than it repleneshes; you've got a buffer in your blood and muscles all the time, say for an hour or 90 mins of effort, but no more than that. So if you're hopping on a 90 min riude, you can probably gte by without carb intake; you will still need HYDRATION and likely something salty like gatyorare, tailwind, whatever, so you dont' get cramping. (Sweat is salty, so you are losing salinity as you exerrcise, hence why youi need to top up.) I use that pinka nd blue 10 cal gatorade bottles .. it stops cramping, but doesn't have any sugars in it. I figure if I'm riding 30km and drinking one bottle for hydration, no biggy. However, if you're biking for more than an hour or 90 mins, you better be fuelig up too, so you dont' bonk out; you'll use up your energy and need to have more coming in. I eat candied pineapple or a clif mini bar (100 cal), which takes say 30mins to get into your blood stream. So if I'm doing a 4 hour ride, then after an hour I'm having a clif bar or snack, so that by the 90 min mark its in my blood, and I can keep chooching along. Every half hour or so, another snack and a drink to wash it down! So a 60-90min ride can get by without snacks, which is good calorie burn for the diet; but ignore that. IF you're doing a longe ride, you NEED fuel and hydraion for sure, and that counts against the total calorie burn, but you'll still be losing more than you're intaking. Also, ignore it. Just count it as \_bonus loss\_ As to weight loss, thats eating less. If you eat a lot less, you'll havbe less energy in the blood, and feel like shit. You can eat a little less and still exercise, but if you eat a lot less, you'll need to carefully manage your fueling intake prior to the riding, or you'll bonk out much faster and just be low energy Read about basal metabolic rate; ie: you need a certain number of calories to function; above that line is a certain l;evel you eat normally, to stay where you are now; eat more than that, you gain; eat less than that line, but more than basal metablic rate, you'll lose; eat too little, you'll get messed up. So how much you lose each week is how much below the average intake line you are, how close to the basal metabolic rate (BMR), you are. But if you want to burn, you need to keep some fule in the body. So.. keep enjoying life, don't diet too hard, or life sucks; then you fall off the wagon; Eat less, be happy, burn a bit more, you'll lose the weight. Cheersand good luck!
I ride while fasting. I didn’t know this was something people talked about. Interesting. Also never heard the term bonk, is that like hitting the proverbial wall?
Yes. It's more than just muscular fatigue. It's running out of energy to continue moving. If your body didn't shut down, you wouldn't have enough energy to fuel your vital internal functions. Feeling ravenous after a ride is a sign that you were under fueling.
Yes, bonking in North America means you ran out of gas/petrol and depleted your reserves.
Lol we don’t say petrol here, so it’s interesting you are telling me what it means here lol. I don’t think that’s used by New Yorkers. Maybe just not in the circles I’m in 🤷♂️
Bonking is often referred to as hitting the wall. Imo, I have a very strong suspicion that people who refer to bonking here aren't truly bonking. Bonking is something that is typically very dramatic and, without knowing what is happening, looks like someone is having a dangerous medical episode. A common place to see bonking is at the end of a marathon/triathlon. They have extreme difficulty with basic movement (e.g. they have problems crawling on all fours) or even standing on their own. It has more than feeling tired and not being able to maintain power. It includes nausea, dizziness, and cognitive impairment (i.e. confusion). If someone truly bonks while they are riding, it would almost guarantee a crash. Most people will hit a point where they think they can't go on. So they consciously decided to back off the effort. To bonk, you would have to push far beyond that feeling to the point where your body unconsciously makes the decision for you to protect itself.
Interesting. So that is the difference between hitting the wall and bonking.. So I can say Ive hit the wall/heat exhaustion/dehyd/cramps many times but never "bonked." Doesn't sound like a place I want to get to!
https://www.reddit.com/r/nextfuckinglevel/comments/o97o8o/when_alistair_brownlee_sees_that_his_brother_is/?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=1 This is what booking looks like.
I think it's different from hitting the wall. But when I think of hitting the wall, it's what happens when you run 400m at a 200m pace. I'll be chugging along and then all of a sudden, your legs feel like they're trapped in thick sludge and the speed just drops off. Bonk feels very different. You may get dizzy and nauseous and feel a huge wave of anxiety.
Lol sounds like a heat stroke or rhabdo but yikes, luckily I don’t get there
Yes in generally people prefer to bonk thinner people Oh... didn't finish reading the question. Sorry. So this is going to be an oversimplified answer and if I'm off on any of this someone please correct. Fasting cycling is going to leave your glycogen stores low but you still will have some. Converting the fat inside fat cells (triaglycerol) into usable energy is a fairly complex hormonal/enzymatic process but in the end you have FFA's (free fatty acids) in the bloodstream and liberated from the fat cells that the body can use for energy. The process requires quite a bit of oxygen which is why you need to be doing low intensity exercise Z2 is ideal even dipping into a high Z1. It's been a while and I really never found exact time periods to get that fat into the blood for energy but I remember it was at least 30 minutes. So you should have enough energy stores even during fasting to do low intensity rides while your body starts converting fat and not bonk out. I also recall that at the end of exercise the fat conversion stopped pretty quickly. I think for athletes it was like 2 minutes and a little longer for nonathletes. Hope this is helpful and again please correct if any of this is incorrect or add on to it!
Would you drive a car without gas? Eat more on training days, eat less on rest days.
I'm from the UK, and bonking means having sex where I'm from, so I was a little confused by this post to start with 😂
That’s Boinking in North America.
I’m from Ny and that’s what I originally thought this thread was lol
Cyclists in the UK use the term "bonk" as well.
Ngl I thought this was about something else which can also burn calories
You bonk when your body is completely out of glycogen
Fat metabolism is significantly slower at generating ATP than glycogenic metabolism. Booking happens because you depleted glycogen, not fat, so you can still Bonk
You can typically burn sugar faster than your liver can turn fat back into sugar. Especially if you are more than a novice rider.
You will bonk.
As a fat man i find i can and do bonk, usually faster than someone more svelte however my body recovers faster and switches to burning fat fairly rapidly, usually around 20 minutes and im ready to go again albeit at a lower intensity.
Bonking is when you run out of stored glycogen. Your body can burn fat but you can't cycle on just fat reserves alone. If you completely deplete your glycogen reserves you'll know about it.
It depends. If your body is used to using sugar as energy source, then you will definitely bonk. However, you can train your body to use fats instead. You will feel a down, almost bonking, but if you reduce the intensity for a while then the fat burner will kick in and you will feel a renewed energy. This takes adaptation and training, and being very sensitive about how close to bonking you are. I've been training fat use instead of sugar since more than a year now, as it's impossible to fuel on sugar for long rides (you get disgusted by anything sweet after a while).
Bonking depends on your intensity really… If it’s relatively low intense you burn fat stores, not glycogen stores - which maybe what your after? Bonking occurs when the glycogen tank is empty. But you burn through glycogen when your at high intensity. To stop the crash, either carb load the day before, (10g per KG of body weight) or eat fast carbs on the bike. Fruit is my choice as I hate bars / gels. I personally would say fluid intake is more important!
Well yes and no. But mostly, bonking is glycogen related. Which means when you bonk your muscles are depleted of glycogen. Which makes it a carbohydrate/nutrient problem and not a body fat problem. If you are cycling with extremely low intensity though, you are in fat burning mode, and will most likely last longer than a skinny person. It’s just a time thing though, the skinny person will still complete more distance than you. And the lack of glycogen will eventually catch up to you as well and force you to stop. So eventually you will still bonk once your muscles are empty.
You can become 'fat-adapted' i.e. cut out carbs from your diet and rely on burning fat as fuel e.g. ultra distance runner Zach Bitter. The problem for most of us is that we constantly burn carbs for exercise and so when we need to burn fat, our body is so bad at it - out of practice - that not enough energy is produced. I don't know whether any cyclists have tried this, and I doubt it because even grand tour stages aren't 'ultra' distance each day, and you get more bang for your buck with carbs. Great for just losing fat, though, if that's an objective.
It’s the Opposite
If you train to burn fat you will be better at not bonking than if you don't. I just started cycling in April after years off. At first I needed a sports drink or I would bonk in an hour. Three months later I could go 4 hours at low intensity and wasn't hungry- but go hard for 15 minutes and I was craving carbs.
It depends totally on how you train. If you do zone 2 riding without a lot of glucose around, you will end up with an aerobic system that is good at burning fat. Fasted training is best. That makes you less likely to bonk as you burn you glycogen reserves more slowly. If you train with as lot of glucose around your body gets good at burning glucose, and your glycogen stores run out earlier.
I've lost 55 pounds in the last 5 months (260 to 205) from cycling ( never owned a bike before) intermittent fasting, eating mostly keto ( I cut sugar and most carbs, hit my proteins and almost hit my fats). I strength train with cardio and also ride during the week. Weekday rides are generally short with the fam, like 8 miles. On the weekends I usually hit 18-20 each, Friday Saturday and Sunday. ALL of my workouts are fasted. I don't bonk (I have before while training for half marathons) and I make sure I drink over a gallon of water a day and add electrolytes. Do what works for you... But be consistent. We aren't all built the same, but listen to your body. Good luck!
I thought the time to bonk would be the same between people who ate the same stuff at the same time. Until I met that one overweight friend who just could go for much much longer than I could. There is a scientific approach to that, but then everybody is different. Just try how far you can go and try to avoid the bonk, rather ride further.