Fast, Furious and Deadly – Carbohydrates for Endurance Sports

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Nutrition for Cycling Part 1: Carbohydrates

I want to start with three examples that have stuck with me and really got me thinking. How do wild animals know what and how much to eat and yet are never fat or chronically ill? How can african hunters run for hours in the midday desert heat chasing antelopes until the animals are exhausted (not the humans!) and accomplish that without breaks for food and water (antelopes are fast). Finally no matter what the advertising has to say, the Tour de France, Ultra mega giga Ironmans are not even close to some of the feats our ancestors performed usually with only survival in mind rather than fame and fortune (the race to the South Pole comes to mind).

The answers can be classified as stranger than fiction, however, by going down to the fundamentals of nutrition, if you can call it that, and the human body and ultimately high performance is an absolutely fascinating story.

Staying alive or using the full medical term – survival – is the goal behind every species on the planet earth. To survive we require energy and as such we posses a fascinating system in place to take care of that. In addition storing energy for the times when food is/will not available is an integral part of the way humans are programmed. What to eat for optimal body function has evolved over roughly 2 million years (with its final version more or less settled around 200,000 years ago) and unlike most of the creatures in nature that eat predominantly food of animal or plant origin (carnivores and herbivores respectively), we have a curse of being omnivores (all eating).

Furthermore at the time of this post the last 30 or so years marked an increase or I should even going as  far as saying explosion of metabolic related diseases such as obesity, Type 2 diabetes, hypertension, cardiovascular diseases. The cynics might say is that we have gotten lazier and eating junk food, and you would be half correct, however, obesity and type 2 diabetes are increasing in children younger than 6 years as well as in newborns. Therefore the heart of the problem lies somewhere else…

In 1977 the infamous McGovern report announcing saturated fat as the end all-be all cause of the cardiovascular disease epidemic ravaging through the United States and hence announcing the first dietary guidelines stating that carbohydrates, rice and grains should form the basis of the food pyramid. Rewinding the clock a bit further we get to a man named Ancel Keys who has gotten himself on the good side of some people in high places. Mr. Keys had been put by the government in charge of determining the minimum amount of calories a soldier can survive on while still being combat worthy. Granted he performed a lot of experiments which would be extremely unethical today such as starvation and testing on mentally challenged patients, the result of his studies were the so called K-rations that are still a staple  (albeit highly modified) in the US army. Following his early successes, while on sabbatical in England in 1952, he noticed that there were enormous increases of cardiovascular disease on the typical English high fat and high cholesterol diet as well as that the richer people both in the UK and US who could afford meats had higher incidence of heart problems.

Throughout the 1960s and 1970s Ancel Keys published a plethora of studies showing higher cholesterol in heart disease patients as well as that diets high in fat raise blood cholesterol. Keys’s ‘masterpiece’ though was the published in 1980 500-page 6-countries study demonstrating that Japan, Italy, England, Australia, Canada and the United States in that order showed a correlation between dietary fat and heart disease (i.e Japan the lowest fat and disease, the United States highest). The first huge gaping hole among the many (excellently detailed by Gary Taubes) in the study’s methodology is that Ancel Keys had data on 22, yes almost 4 times as many countries, and if he had plotted that data he would have gotten a scatter, ie absolutely no correlation even for the most creatively minded statistician. Yet he chose the 6 that nicely fit his hypothesis. In addition and it is something equally important that will come many times in content of this site – association does not equal causation, I repeat association IS NOT causation. A very general and simple example to illustrate: I am Bulgarian and 2m (6’7″) tall, so that leads to the conclusion that Bulgarians are a tall folk. I can tell you that is not the case, and judging by the fact that I get asked almost daily “All Bulgarians must be tall as you, no?” association is very often mistaken for causation.

However, to get back to Mr. Keys, he chose to leave out indigenous tribes such as the Inuit (North America) and Tokelau (Oceania), Maasai and Rendille (Afirca) who predominantly animal fat and have the lowest prevalence of heart disease on the planet. Vihjalmur Stefansson a Canadian Arctic explore and ethnologist (pictured dragging a seal) spent 10 years living with the inuit and learned to eat their food, composed mostly of seal blubber, karibou meat, fish and eggs, and had never felt healthier. Interestingly the inuit viewed plant food as not being “proper human food” and only ate some roots when in dire need. He documented his experiences in a number of The Fat of the Land. After his return back to New York, he couldn’t stand the food and had to import Inuit food. His observations were immediately labeled controversial in the light the conventional wisdom that ‘balanced diet’ is the healthy diet.  In 1928 himself and Karsten Anderson, 38 year old Danish Explorer, became the subjects of a yearlong experiment to put an end to the meat-diet controversy. The whole experiment was strictly supervised by a committee of a dozen respected nutritionists, anthropologists, and physicians. For the initial three weeks Stefansson and  Anderson were fed a mixed diet (fruits, grains, vegetables, meat) while being subject to a LOT of tests. Afterwards they were moved to Bellevue hospital where under 24hour surveillance they were fed only meat. After 3 weeks (Stefansson) and thirteen weeks (Anderson) both men were released and ate only meat for one year. The constant urine tests showed that the “acetone [ketone] bodies were present in amounts so constant that fluctuations in the carbohydrate intake was practically ruled out.” The conclusions were dramatic due to the fact the expected severe vitamin deficiencies and health decline in both men did not occur, quite the opposite. Albert Scheiwzer, who later went on to win the Nobel Peace in 1952 for his missionary work,  and Samuel Hutton were among some of the colonial and missionary physicians who provided historical observations of the changes that occurred to the indigenous populations that were exposed to the “Western diet.” In the early 1900s carbohydrate foods such as sugar, molasses, white flour and white rice were the staples that the colonists could bring by ship without spoiling or becoming rodent feed. Soon after exposure or the now popular term ‘nutrition transition,’ Western or diseases of civilisation such as obesity, diabetes mellitus, cardiovascular disease, hypertension and stroke, various forms of cancer, peptic ulcers, diverticulitis, gal stones, haemorrhoids, varicose veins and constipation. When any of those condition appeared, the other would follow eventually. Investigators proposed a hypothesis that the disorders had one common cause – easily digestible, refined carbohydrates. In the light of Ancel Keys’ (bold and unsubstantiated) claims that it was fat was the problem with carbohydrates being the solution, the carbohydrate hypothesis was rejected without any further examination.

The above examples are merely one aspect of a greater concept and I am quoting Gary Taubes directly:

You should not let preconceived notions about a ‘healthy diet’ bias the science and the interpretation of the evidence itself.

Which brings me to the next point…

Vihjalmur Stefansson dragging a seal. Photo courtesy of the Dartmouth Library

As far as humans are concerned we have no essential need for carbohydrates, which means to say our metabolism is perfectly capable of making all the stuff it needs, be it carbohydrates (glucose) from non-carbohydrate food. There is NOT A SINGLE clinical condition (disease) of carbohydrate deficiency. If it is essential and we are missing it, we will get sick. Not the case with carbohydrates, not even close. To get an idea why here is a short description of how to body responds to food and calories as well as bring in some hormones into play – enter Insulin and Leptin.

Not surprisingly, like all things human it starts with the brain. Driven by brain signals (hunger, reward, stress) we ingest various foods – ie a combination of fat, protein, carbohydrates, fiber and some micronutrients. It enters the stomach where hydrochloric acid starts the digestion and afterwards the food passes to the small intestine where enzymes break it down to its building blocks – fats gets turned to fatty acids, proteins are broken down to their individual amino acids and carbohydrates are cleaved to simple sugars – mostly glucose with varying amounts of fructose. I underline fructose because it is quite interesting and will be the focus of the next part of the series. We cannot digest fiber so it speeds up the transit of food through the small intestine as well as causing the other nutrients to be absorbed slower. From the small intestine the simple sugars and amino acids travel via the circulation to the liver, while the fatty acids travel via the lymphatic system. The important point it that all nutrients go to the liver first for processing and whatever can’t be taken up there ends up in the general circulation (bloodstream). The rising blood levels of fatty acids, amino acids and glucose reach the pancreas which starts the release of insulin.

Insulin signalling causes several events – glucose gets converted to glycogen to top up the liver energy reserves, amino acids gets shunted to muscle cells, excess fatty acids (blood lipids) get cleared and put in storage inside the fat cells as triglycerides as reserves for a “rainy day.” The take home message from the process is that insulin causes energy storage (fat), no insulin no energy storage, lots of insulin = lots of fat and NO fat burning. Once the insulin levels drop, the whole process goes in reverse – the triglycerides from the fat cells get broken down to fatty acids and mobilized in the bloodstream where they to go to the liver and other organs where they are used to energy. These two processes happen in the human body all the time 24/7/365 – burn what you need, store the rest.

The next logical question is how does the body know how much energy it needs? As mentioned above it starts with the brain and no two opinions about it – energy balance is absolutely vital for survival and as such it is extremely regulated with multiple redundant systems to make sure we don’t die. If there is enough energy in storage the brain signalling is to go out and spend energy. When not enough energy is in storage the brain goes into energy preservation/acquisition mode – and minimizes energy expenditure and in short you feel like crap. That by the way is what happens in calorie restricted diets – you are hungry all the time and have low energy and want to sleep the whole day and you might even gain weight since the brain wants to store energy at all costs to ensure survival. But I digress….

How does the brain know how much stored energy (fat) is there? It receives information from the fat cells that release a hormone called – leptin. Low or no leptin equals brain starvation and energy preservation and increased appetite, high leptin translates into normal energy balance and utilising the stored fat. In addition high leptin levels send a signal back that no energy storage is needed so less (of the energy storage hormone) insulin (see above) is released. Mice that are genetically engineered to lack the leptin gene get humongous and don’t move unless you put their food at the other end of their cage. Then they move there eat the food and sit again – lazy, hungry and overweight. All in all we are perfectly capable of regulating how much energy we need to consume according to what we have to do – cycling or otherwise. The famous example goes that if you eat 20kcal more per day (a bite of food) you will be 10kg (20lb) overweight in 10 years. Nobody can count calories that precisely no matter the willpower, period.

The real twist comes that although different hormones insulin and leptin with their own unique mechanism of action, they both share a similar signalling cascade in the brain – insulin inhibits (blocks) the leptin signal and forces weight gain. Why? That is how we get from the small baby to the adult, and why you can eat everything ALL the time in puberty and ‘get away with it.’ Puberty and pregnancy are both characterised as hyperinsulinic states and why some women develop diabetes when pregnant. If the mechanisms didn’t work like this, we would be all stuck in pre puberty with lots of energy to use and inability to gain weight/grow/develop – not a good state for survival of the species.

Therefore high insulin state causes the feeling of starvation of sorts which in turn causes the need for more energy storage (high appetite and lack of desire to be active). The culmination of the vicious circle is obesity and all that comes with it, however, this is not the focus here. The food that drives insulin high is carbohydrates or the in their digested form glucose and when it comes to endurance performance in the 1930s several studies showed that low carbohydrate levels occurred in athletes (some of the studies can be found here, here and here). To briefly summarize – the model showed that giving athletes glucose was a way to reverse fatigue  as well as that glycogen (glucose) levels in the muscles decrease in response to exercise. In addition muscle glycogen and endurance was lower in athletes fed low carbohydrate diet as compared to their high carbohydrate peers. The grand conclusion formulated in 1973 by Costill et al. was that “depletion of endogenous carbohydrate stores has been shown to be the limiting factor in the ability to perform long-term exercise.” First the fact that two events occur at the same time does not imply causation – as stated many times on the blog – association is NOT causation.

Findings like this one coupled with the running boom in the 1970s led to the birth of the sports drinks industry which to this day continues to sponsor similar ‘research’ while the elephant in the room makes its presence more and more known. Which elephant? Even the leanest of us have 40.000+kcal worth of fat in our muscles while only ~2000kcal of glycogen as well as that the human body can burn 750+kcal per hour during exercise, however, can only absorb  ~350kcal/hour.  No matter what type of magic wonder simple or complex sugar the manufacturers shove in their products, it cannot overcome the physiological specificities of us as humans. The carbohydrate model further stated that fat simply cannot be oxidized (burned) fast enough to support high intensity endurance exercise, which of course is supported by the fact that insulin (released in response to carbohydrates) inhibits fat burning. The absolutely fascinating work by Dr.Stephen Phinney and Prof. Jeff Volekshowed among many studies that after a ~4 week adaptation to a very low carbohydrate diet (<50g) endurance in highly trained  athletes (cyclists included), did not suffer and quite the opposite. The science and what is just starting to slowly gain ground brings me back to where this post started.  The african hunters chasing the antelopes for hours without fatiguing and not having the wonder sugar drinks we see advertised and to as pointed out by Vihjalmur Stefansson and his life with the inuit, not by bread alone is how we will endure.


The human body is perfectly capable of regulating it’s energy balance thought the hormones insulin and leptin, that no calorie counting methodology can better. In addition there is no essential need for carbohydrates in the human metabolism. Ingestion of carbohydrates, particularly ones that are very rapidly absorbed (refined carbohydrates present in any processed food such as flour, sugar, starch) leads to elevation of blood glucose and subsequent release of insulin that causes the storage of excess energy as fat and inhibition of using fat as fuel. Persistently elevated levels of insulin block the action of the starvation hormone leptin, effectively tricking the body that it’s in a state of malnutrition with all of the common symptoms such as increased appetite, low energy, etc.  Furthermore the insulin induced starvation increases the body’s need for preserving energy (into fat) hence causing further release of the energy stowaway hormone insulin into a vicious circle, with obesity and metabolic syndrome as the final stages.

Incorrect conclusions about the role of dietary fat in the cause of heart disease culminating in the 1977 dietary guidelines stating that carbohydrates, specifically grains and bread should form the basis of the human diet as well as misguided understanding of the role of carbohydrate need during exercise further reinforced by the sports drink/supplement industry has created the popular model that endurance exercise and carbohydrates go hand in hand. However, by looking at examples that still exist today such as the african antelope hunters as well as historical evidence by travellers like Vihjalmur Stefansson together with recent research by Dr. Stephen Phinney and Prof. Jeff Volek, carbohydrates are not essential for endurance athletes as well as the main cause behind the now pandemic levels of metabolic diseases such as obesity, type II diabetes and cardiovascular diseases in the general population.

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Home » Food » Fast, Furious and Deadly – Carbohydrates for Endurance Sports

8 replies on “Fast, Furious and Deadly – Carbohydrates for Endurance Sports”

Sorry but I strongly disagree, it might be ironic how there is also scientific data backing the fact that obesity and diabetes is caused by fat and not carbohydrates. I’ve been eating a high carb low fat diet for 2.5 years and I’ve been feeling a lot better. Not trying to get a whole debate started but there is as much scientific backing for the “other side”.
Would you care to share your experiences / experiments with diets and your performance?

Hi Emile

Thanks for your comment. I welcome constructive discussions. One of the first things that I learned to be very careful with is that a good number of the epidemiological studies such as the ones linking this or that disease to that or other food type are association studies – association is not causation, two events occurring at the same time are not necessarily related. Same goes to the current dietary guidelines set up around 1977. One should be extremely careful to check the methodology the research used, especially given the fact that the supplement and food industry sponsor most studies on the matter and unlike the pharmaceutical industry, food companies are not currently bound by any regulations besides the health/hygiene ones. Ben Goldacre’s – Bad Science is a must read when it comes to that. In addition one thing that nobody denies is that the modern western diet is a major cause behind a lot of the (chronic) ‘diseases of civilization’ and this is not a recent development – Gary Taubes has 2 books on the matter; his writing style is superb, definitely something to check (or his talks on YouTube). What we are starting to find out about obesity as a hormonal disbalance disease (insulin is a hormone) these days was already known pre WWII by German/Austrian scientists. That knowledge got buried down due to it being in German and the loss of the war by Germany.

Furthermore, my goal is far from starting or disproving this or that fad/diet. I aim to show that there is another side of the story. First carbohydrates and sugar (sucrose) are often used interchangeably. I advise you to look at my post on sugar (Sweet Little Lies), since there is a lot of information i was also not aware while doing my research. Cutting out refined carbohydrates (flour is a refined carbohydrate as well) and sugar is not the same as cutting out carbohydrates entirely. It is just impossible to eat as much carbohydrate when eating real/non processed foods. So according to the the current ‘standard’ it comes out as low carb. Second not all fats are the same (my post on that is coming in the nutrition series in the coming week or two). In the race to cut out animal (saturated) fats the use of vegetable seed oils has skyrocketed. These fats are Omega 6, liquid at room temperature and highly prone to oxidation/going rancid and are as well pro inflammatory. Eating too many of them overloads our inbuilt safeguard processes. This is behind the main cause behind heart disease. I am not going to go into trans fats since even the food industry doesn’t deny anymore they are bad for you. David Gillespie’s – Big Fat Lies is a revelation of a read with plethora of references if you are into the science itself. Therefore in the end eating real non-processed foods with no refined carbohydrates and avoiding seed oils comes out to what is referred as a high fat/low carb diet. To determine whether it is all fact or fiction you have to be aware of both sides of the story. Most importantly you have to look at the bigger picture and as much as I hate the word – take a holistic approach.

As far as my experience with the so called high fat/low carb diet is extremely positive. I will have some blood work done in the coming months to compare that to my tests done while on the high carb diet. I will get into more details when i cover my 3-4months on the Maffetone training (I have a post on the training itself). I did start very slow, however, I see improvements and as I said i will post more details when I have given it long enough time, it’s not racing season for another 4-5months. In general my energy levels are extremely high during the day with almost no fluctuations and the brain function is amazing, I read sometimes 2-3 books a week and understand and reason the ideas in them with great clarity among other things. Even friends notice, without me telling them that I am not getting into ‘killing/grumpy mode’ every 2-3 hours in search of food/snacks. My weight is close to mid-season peak form while we are mid-November right now and besides eating real foods and no refined carbohydrates/sugar i don’t pay attention/count calories. Last but not least my gut function is the best in a very very long time; this has been a weak spot for me for more than 15 years and the improvements there are quite noticeable and not something I was expecting.

That being said you can subscribe to the blog via RSS/Email/Facebook (links on top right) and follow how my current diet unfolds as well as for the upcoming posts in the Cycling nNutrition series.=)



I seems to naturally prefer a ‘balanced’ diet, lots of lentils and occasional meat, Fruit but no refined sugar. During endurance mtb races i was stuffing myself with synthetic ‘carbs’ and doing Ok but was having trouble with fasted mtb training rides more than about 2.5 hours long where i would get the chills and bonk. Note for these rides im averaging a hr 30-40bpm above my maf rate. A nutritionist asked me to experiment with carious sports energy bars. What i found is that for rides longer than about 90 minutes i do better and recover faster if i take in a clif bar every 45 minutes. With that added sugar im good until my muscles get fatigued at 9-10 hours. The most amazing thing is i can stuff myself with handfuls Of gummy bears and there is no perceived insulin response – the sugar is sucked out of my bloodstream as fast as the stomach can deliver. Your paper seems to be discussing ‘diet off the bike’ but can you speak the pros and cons of taking in carbs while on the bike and above lt? I promise i would fail and barf if i tried to eat just meat and fat while riding hard.

Hi Eric,

Thank you for your comment. First I will share an example that I find illustrates how the whole fat/glucose matabolism/burnign works. It is a candle with the the flame being carbohydrates and the body being the fat. You need *both* to have a functioning metabolism. The amount varies based on how (boy do I hate that term) ‘fat-adapted’ you are and also on intensity as well as what you ate (or didn’t) just before your workout. There are some more details with nice graphs to illustrate it in my artilce in the following link.

The take home message is that if you burn a lot of fat, you need a correspondingliy higher amount of carbohydrates. Here is a bit where the confusion (and exucses) start – the above is NOT an excuse to pound sugary drinks/energy bars/etc. There is one exception which i will get into a bit later.=)

From the limited information you have told me, there are a couple of things that stand out. Though I have a couple of questions for you first to better understand your situation – you mention MAF heart rate and zone. What is your experience with MAF trainig, how long have you been doing it, do you measure your progress with MAF tests, have you done any experiments with carbohydrates (ie the 2 week test)?

1. Bonking on fasted training rides of 2.5h. This is a red flag that your metabolism still relies primarily on (very) limited carbohydrate sources. Even if you are on the oppsite side of the spectrum (burning almost exculisvely carbohydrates) you should be able to do do 2-2.5h hour rides even fasted without too much trouble, especially if they are lower intensity. 30-40bpm above MAF is very high intensity though still manageable – if your metabolism burns predomintnaly fat, bonking with chills and such is almost never a problem. What is your MAF HR (and your age) and what do your MAF tests to this day show?

2. Eating every 45min is another hallmark of metabolism not relying on fat. Even at very high intensity efforts, you should not need to eat to keep to sustain your training pace. Even so anything longer than 1h at maximal efforts is aboslutely counterproductive from a training point of view (you are doing submaximal power output due to fatigue and we all know how to do that…ie your effort feels maximum, not your output/speed/pace). *Racing* is a whole another matter (more on that a bit later). Though even than eating at the very beginning sounds a bit off to me. I need a bit more info on what type of events you are doing and what happens during them.

3. Gummy bears and insulin response. You mention perceived but have you actually done some insulin/blood glucose testing? What do you call a perceived insulin response?

I saved *racing* scenarios as last since those are unique. There everything is ramped up so high and you do need to keep the carbohydrate ‘flame’ burning to sustain fat metabolism. The flame can go out and you slow down significantly – it is not as bad as bonking, though it is definitely unpleasant. Fast/junk carbohydrates work wonders here, especially over multiday/overnight events. Racing is only a tiny percentage of the time so it is rather an exception to pretty much all the MAF rules/principles. Most of your training should be done at MAF pace with very small amount of sessions reserved for maximal efforts when your condition (ie well rested) permits it.

Here there is something very positive which you have been doing yourself – experimenting what works and what doesn’t for you in training. Meat and fat will NOT sustain high efforts (the keto-athlete graph on the link I showed you, that is for sure, though high intensity scearios are a bit different and do require some experimentation/fine tuning.

This is all I can tell/advise you with the information you have given me, so let me know if you have further questions and/or I have missed something.


Interesting read. I do find eating carbs in the morning makes me hungry during the day. I am on a calorie deficit as I am trying to lose weight. However, I do try to consume some carbs before and during a longer MAF range ride (2 hours at 141 HR). Yes understand the MAF formula is meant to be an estimate of fatMAX so in theory, I should be able to ride fasted but I find having a little food helps me get through the ride.

I wanted to check, how many grams of carbs can I / should I consume to avoid getting an insulin spike?

Thanks for all you interesting articles.

Hi Jeremy,

Thank you for your comment and for the nice words. There are a couple of things from what you have told me that stand out to me:
1. Eating carbs in the morning makes you hungry during the day+calorie deficit
2. Longer MAF rides (2hr @ 141bpm).

Regarding the first part, I would need more information to give you more specific advice. Though some general pointers. Why are you eating carbs in the morning and what carbs? The real problem is refined carbohydrates such as bread, pasta, sugar, oatmeal, etc. You mention that you are in a calorie deficit in order to lose weight. This is something which I call ‘barking under the wrong tree’ What i mean here, in an simplify way, is that once you become (boy do I hate that term) ‘fat-adapted,’ you are without the constantly high (not just spikes) of insulin your *metabolism and hormones* change and as such your cravings disappear and you don’t store extra weight in fat and get rid of extra weight. This should be step 1; while calorie deficit works to a degree it is largely for the same reasons – hormonal and metabolic changes (due to for example eating less insulin release causing foods because well you eat less). However, keep in mind that the hunger signal we get is very powerful (back when food was not everywhere we wouldn’t have gotten out to search for something to eat if it wasn’t…) and as such we should not completely ignore it (and hence in extreme cases we go into very low energy mode (lower body temperature, fatigue, make extra fat VERY easily, etc.) in order to ensure survival. As you have probably read in the above article refined carbohydrates kinda short circuit the hunger signal so you have to fix that first before playing around with calorie deficits. The latter is something that unless you are involved in sports with weight classes, or where power to weight ratio (ie cycling) is a critical factor for success, is best left alone in my opinion. If you fix (lower) the insulin everything else will largely start to take care of itself (overfat, etc.)/. With one exception here is that if you are deficient in something (particular mineral (fro example magnesium), vitamin, etc) even if you eat enough calories, you will still be hungry because your body is trying to find it. ‘True’ cravings are actually helpful

The second part is that 2h rides @ your MAF heart rate seem to be challenging for you, possibly indicates that you are still have some ways to go to as far as switching to burning predominantly fat rather than carbohydrates. This is normal in some cases and it requires you to eat something to get through the ride. Though that should become less and less to as you mention not needing any food and that not having any negative impact on your ride.

Which brings me to your final question: how many grams of carbohydrates do you need? That is for you to determine through self experimentation (and that means getting it wrong on occasion). This is the part of the MAF method that does not get nearly enough attention – you should learn to read the signals that your body is telling you since we already have the best health and fitness tracker ever made – our brain. The two week test as described in Dr,Maffetoine’s Big yellow Book where you cut off all carbs and then slowly start by reintroduce some is a good starting point. Also Dr. Atkins’ “The New Atkins for a New You” if I am not mistaken has some very well defined ways how to start reintroducing carbohydrates in your diet. Of course it all goes without saying that any kind of junk food and refined carbohydrates do not figure in your plate.

I have given you quite some information, if there is anything you need more help, please let me know in the comments here or via the Contact section (top right) of this website.

All the best,

Thanks Nikola, that is very helpful.

I used to have 30 grams of granola or half a cliff bar and spiked my drink with a dextrose heavy electrolyte mix. After reading your article, I have changed to 10 grams of edamame (or similar like lentils) along with a multivitamin and fish oil. Drink has been switched to a carb free electrolyte mix as well.

So far so good though I do have some tiny bit trail mix along the way, more to kill off any distracting cravings along the ride. Maybe that will go over time.

I am doing back to back rides from Monday to Friday so I find that Mondays are fine but Fridays are a drag due to some muscle fatigue and I start averaging 125-130 HR instead of the targeted 141.

For diet, I have swapped out all refined carbs with an extra serving of non-starchy veggies like broccoli.

I will have a read of the books you mentioned. BTW have you done the courses on the MAF website? I would love to but they are quite expensive. Let me know what you think of them if you have gone through them.

Let me know your reactions or have any other suggestions. Thanks again.

Hi Jeremy,

I somehow have missed your comment…apologies for the delay in responding to you.

What you just told me is a perfect example of taking charge of your training – meaning realising that granola, cliff bars and dextrose (none of which have a place when it comes to MAF and fat burning) are not doing you any good and replacing them with edamame and carbohydrate free electrolyte mix. This is more or less how the whole MAF method should work – experiment what works. With trail mix be careful with dried fruits, they are quite sugary and insulin spike causing.

As far as riding 5 days back to back, the fatigue and hence drop in HR is normal, my suggestion is if you can take the Wednesday off (do some walking and/or mobilisation, here Kelly Starret’s Youtube channel and books such as “Becoming a Supple Leopard” are really useful). Unless absolutely necessary riding through fatigue, especially at the beginning stages of MAF, can be a bit counterproductive.

The books I mention are a good starting point, though since we do live in the digital age, I suggest also the Endurance Planet and Primal eEndurance/Primal blueprint podcasts. Start with the first episodes and with the ones (on Endurance Planet) where Dr. Maffetone is a guest. They cover a lot of common questions that a lot of people (myself included) have when starting. There is a book named Primal Endurance as well which I also recommend. Since MAF is , (I hate using that word) holistic, you can find more suggestions for improvement in many other areas, in my booklist here ( With that being said, I have not done any of the courses on the MAF website, though I suspect (and this is my largely uniformed opinion) is all the information out there, just more organised and systematised. There is plenty that can be done just going off from The Big Yellow book and podcasts before diving into the weeds. I can be wrong though…. Once you become more proficient and in tune with the positive changes you are experiencing due to the MAF method, you will see repetitive patterns in all the information in podcasts, articles etc. (ie refined carbs are bad, do not train at higher than MAF HR, do not overtrain, etc.)

As usual if you have any further questions, please let me know.

All the best,

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