Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
19 May

A Metabolic Paradigm Shift, or Why Fat is the Preferred Fuel for Human Metabolism

There’s a good reason so many people (mostly the sugar-burners, whose disparate group includes fruitarians, veg*ans, HEDers, body-builders, most MDs, the USDA and virtually every RD program in the country) can’t seem to grasp why a lower carb, Primal approach to eating is a better choice for health and fitness: their fundamental paradigm – the core theory that underpins everything else in that belief system – is flawed. They remain slaves to the antiquated notion that glucose is the king of fuels, so they live their lives in a fear of running low. The truth is, fat is the preferred fuel of human metabolism and has been for most of human evolution. Under normal human circumstances, we actually require only minimal amounts of glucose, most or all of which can be supplied by the liver as needed on a daily basis. The simple SAD fact that carbs/glucose are so readily available and cheap today doesn’t mean that we should depend on them as a primary source of fuel or revere them so highly. In fact, it is this blind allegiance to the “Carb Paradigm” that has driven so many of us to experience the vast array of metabolic problems that threaten to overwhelm our health care system.

It boggles my mind that such a large segment of the so-called health and fitness community would continue to defend high carbohydrate diets with such tenacity. It should all be very obvious by now. The studies keep piling up indicating that carbohydrate intake is the major variable in determining body composition and that excess glucose from carbohydrate intake (especially from processed grains and sugars) is the primary culprit in obesity and in many disease processes. It follows logically that if you can limit carb intake to a range of which is absolutely necessary (and even up to 50 grams a day over) and make the difference up with tasty fats and protein, you can literally reprogram your genes back to the evolutionary-based factory setting you had at birth – the setting that offered you the opportunity to start life as a truly efficient fat-burning organism and to continue to do so for the rest of your life as long as you send the right signals to your genes. Becoming an efficient fat-burner is the major premise of the Primal Blueprint eating and exercise strategies.

But logic doesn’t rule when you are stuck in the Carb Paradigm, so I still see some misguided bloggers decrying the Primal Blueprint eating strategy as potentially harmful for its relatively low carb intake or stating that my advice to “generally keep carbs under 150 grams a day unless you’re an athlete” is ridiculous. How many more times do I have to overhear a trainer advising a still-portly client to “eat 5 or 6 small meals throughout the day, always with some carbs, so you keep your blood sugar up and don’t go into starvation mode.”? It’s time to stop this nonsense and reframe the current views of human metabolism to accurately reflect the two and a half million years of evolution that shaped the current human genome – a perfect DNA recipe that fully expects us from birth to function largely on fats.

It’s time for a Metabolic Paradigm Shift within the health and fitness world.

The Faulty Carb Paradigm “Logic” Goes Something Like This

The basic underlying assumption is that glucose is the preferred fuel of most cells; BUT, because we can’t store very much glucose (as glycogen in liver and muscles), we need to provide a continuous source of glucose in the form of exogenous carbohydrate (high carb meals) to keep the brain, blood, and certain organs humming along and the muscles primed for activity. AND, if we don’t feed ourselves enough carbohydrate every few hours, our blood sugar will drop and we’ll go into “starvation mode” and cannibalize our precious muscle tissue. AND any lack of regular glucose refilling (i.e. skipping a meal or fasting) will cause cortisol to rise, which will have additional deleterious effects. FURTHERMORE, an excess of glucose in the bloodstream is known to raise insulin and will predispose excess calories (from all sources) to be stored as fat. THEREFORE, we should also be doing a lot of moderate-to-heavy cardio or lifting activity most days to burn off this excess stored body fat. HOWEVER, if we want to be ready and able to exercise frequently and strenuously to burn off our stored fat, we need to eat lots of complex carbohydrates between workouts to refill our glycogen stores. And ULTIMATELY, the only way to lose weight is to restrict calories (calories in<calories out), BUT if you’re working out regularly, it’s almost impossible to maintain a calorie-restricted regimen and still be able to work out hard enough to burn appreciable calories. Sheesh.

Sure, there are exceptions, like the driven and genetically gifted types, who can train long hours, refuel on carbs and not add much body fat (hey, I was one). But unless you love to work out incessantly and have really lucky familial genes, the Carb Paradigm is an unsustainable and ridiculous literal and figurative treadmill, a self-fulfilling prophecy for most people who tend to gain weight steadily and insidiously over the years and wonder why. If you are one of the 60+% of the American population who is overweight, the above scenario plays itself out because you have spent your life programming your genes in the direction of being an effective sugar burner and, as a result, have become dependent on a fresh supply of sugar (carbs) every few hours. Naturally, in the presence of all that glucose, and provided you actually do some exercise, your genes will eventually get the signals to up-regulate the enzyme systems, pathways and receptors involved in sugar-burning and fat storage and they’ll down-regulate all those involved in accessing and burning fat for energy. Of course, that doesn’t make it right, but it sure makes it appear as if glucose is king. What makes it worse, if you don’t exercise, you head down the path to insulin resistance and/or obesity.

The Problem: The Basic Assumption of the Carb Paradigm is Wrong

Glucose is not the preferred fuel of muscle cells under normal human resting metabolic conditions or even under most normal human movement patterns (exercise). Fat is. Sure, given an unlimited supply of glucose and regular refilling of glycogen stores, skeletal muscle will burn through it during exercise the same way a fire burns through kindling when that’s all you have to offer. The body can shift carbohydrate oxidation to keep up with intake. But skeletal muscle can burn fat with great efficiency (and far less oxidative fallout) at relatively high outputs for very long bouts. Cardiac muscle actually prefers ketones, and the brain can run just fine (maybe even optimally) on a blend of ketones and minimal glucose.  Our survival as a species has depended on these evolutionary adaptations away from glucose dependency. Entire civilizations have existed for ages on what is practically a zero-carb diet. Think about this: there is actually no requirement for any “essential dietary carbohydrates” in human nutrition. It’s possible to live a very long and healthy life never consuming much – if any – in the way of carbs, provided you get adequate dietary protein and fat. The same can’t be said for going too long without protein or fat. Cut too far back on either of those macronutrients and you will eventually get sick and die.

The Evolutionary Model

Fat and protein were the dominant macronutrients (when food was even available) over the majority of our two-and-a-half million years as evolving humans. The lack of regular access to food and a scarcity of carbohydrates for much of this time necessitated that we adapt efficient pathways to readily store and access body fat for energy if we were to survive day-to-day and generation-to-generation. Our movement patterns were such that we never required large amounts of glucose or that we needed to store very much glycogen. It was predominantly fats, ketones and the minimal infusion of glucose via gluconeogenesis that got us here. Dietary carbs were insignificant. In fact, when you consider how ridiculously small the body’s glycogen reservoirs are, you understand that it would have been impossible for us to survive as a species if glucose were truly the “preferred” fuel. The liver, the main back-up glycogen/glucose storage facility for the brain and other glucose-burning organs, can only store about 100 grams of glycogen. Less than a day’s worth. Your muscles can only hold another 350-500 grams, barely enough to run for 90 minutes at a reasonable clip, and that glycogen isn’t even available to provide fuel for the brain. Meanwhile, we have a virtually unlimited storage capacity for fat (like 100,000 grams or close to a million calories on some people). The reason glycogen storage wasn’t necessary is because, between our copious fat storage capability, easy access to fats as fuel, gluconeogenesis and ketones, we just didn’t need much. Evolution tends not to reward structures or functions that take up unnecessary space or waste energy.

So How Much Glucose Do You Really Need?

Much less than most people assume. At any one time, the total amount of glucose dissolved in the bloodstream of a healthy non-diabetic is equivalent to only a teaspoon (maybe 5 grams). Much more than that is toxic; much less than that and you pass out. That’s not much range for a so-called “preferred” fuel, is it? Several studies have shown that under normal low MET conditions (at rest or low-to mid- levels of activity such as walking and easy work) the body only needs about 5 grams of glucose an hour. And that’s for people who aren’t yet fat-adapted or keto-adapted. The brain is the major consumer of glucose, needing maybe 120 grams a day in people who aren’t yet on a low carb eating program. Low carb eating reduces the brain’s glucose requirements considerably, and those who are very low carb (VLC) and keto-adapted may only require about 30 grams of glucose per day to fuel the brain (and little-to-none to fuel the muscles at <75% max efforts). Twenty of those grams can come from glycerol (a byproduct of fat metabolism) and the balance from gluconeogenesis in the liver (which can actually make up to a whopping 150 grams a day if you haven’t metabolically damaged it with NAFLD through fructose overdosing). Bottom line, unless you are a physical laborer or are training (exercising) hard on a daily basis, once you become fat-adapted, you probably don’t ever need to consume more than 150 grams of dietary carbs – and you can probably thrive on far less. Many PBers do very well (including working out) on 30-70 grams a day.

The Fat Paradigm

The Fat Paradigm, under which the human species has thrived quite effectively for two and a half million years, recognizes that human metabolism is pre-programmed by evolution to be primarily fat-based (the real preferred fuel). In other words, our genes expect us to function optimally when we consume fats and can easily access our stored fat. The Fat Paradigm acknowledges that the body is able to manufacture adequate glucose as needed. It acknowledges that most typical human movement patterns can be fueled almost entirely by fats and/or ketones (PDF) if need be, but can draw on glycogen when energy bursts are required (and which can then be replaced over time). It acknowledges that fat (and cholesterol) are not the proximate cause of heart disease. It acknowledges that fat cells are designed to release stored fatty acids as required, especially during times of scarcity or fasting. It allows for intermittent fasting as a means of accelerating fat loss without sacrificing muscle tissue. It increases insulin sensitivity, modulates energy and mood swings, and allows for a normal and healthy drop in hunger and cravings. There is a downside, however: you can’t train long and hard day-in and day-out in the fat paradigm.

Now then, having explained all this, please understand that I am not carb phobic. I actually permit more carbs in the Primal Blueprint than many other low carb eating strategies. I prefer to view carbs as the “elective” macronutrient, as a tool to use to manipulate your glycogen levels as needed. Low carb isn’t even the main objective of eating in the PB: eliminating grains, sugars and seed oils are the primary objective. Of course, when you get rid of that crap and naturally limit your carb intake to veggies, root tubers and a few fruits, you almost invariably decrease carbs to under 150 grams a day. And that emulates our ancestral dietary intake.

I came up with a simple Carbohydrate Curve a few years ago that offers a pretty concise picture of where most people ought to fall if they are seeking optimum health and energy, depending on their size, weight, sex, age, goals, etc. Now, many hundreds of thousands of user experiences later, I am finding that the Curve is pretty much spot on for a large segment of the population.

When I say generally that a chronic intake of over 150 grams of carbs can lead to insidious weight gain over a lifetime, I am factoring in the concept that many people are at the effect of a familial genetic predisposition to storing fat easily under the carb paradigm (the 60+% overweight). I am also factoring in the drop in metabolism that happens naturally with age, as well as the fact that PBers don’t NEED to purge and refill glycogen stores every day via exercise. Yes, there are some people (a small percentage of outliers) who might maintain pretty decent body composition at up to 300 grams a day on little exercise. I would bet that they also are selective about the carb sources and do a better job of controlling overall calories, so there’s little excess to store. For most of the population, that 150 mark remains a good average level for maintaining ideal body composition.

Well, that was a lot to digest today. You see where I’m going with this. I need your help in showing the health community that their basic assumptions are wrong and that they need to make a Metabolic Paradigm Shift. I’m sure there will be lots of specific questions, so bring  ‘em on and I’ll do a follow up post in a week or two.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Here’s something I did. It’s nothing close to primal, but it worked. While I didn’t gain any muscle, I did not lose any either. I lost 5 pounds of fat and I can attest to that by being able to feel more of my bones and abdominal muscles after this diet. I also woke up at 7:00AM and went to school which required walking every 45 minutes to the lockers and between classes, and walking to the bus. I was two months from turning 18 at the time.

    For every day for one week, this is strictly what I ate:

    – 1/4 cup of oatmeal

    – 1 bowl of rice (2/3 cups if the quantity of that rice was raw)
    – 1.5 bowls of a tofu based dish (When I say bowl, I’m referring to those typical blue and white Chinese bowls)
    – 1.5 bowls of vegetables (vegetables were always eaten after the rice and tofu)


    After doing this for one week, I did not gain any muscle, but I did not lose any either. I could feel my bones and abdominal muscles more “clearly”. I am really sure that I consumed at least 126 grams of carbohydrates every day from the oats and rice. What’s going on?

    Saab wrote on December 5th, 2011
    • That’s not a sustainable diet. It’s very unsatisfying, wouldn’t you say?

      Patrick wrote on January 2nd, 2012
    • It’s called starvation. You are eating well below the amount of calories you are burning daily, and it is taking an unhealthy toll on your body (and you probably did lose some muscle mass in the process). You should never eat below your basal metabolic rate. You should eat between your basal rate and your TDEE rate if you are trying to lose fat safely over time (Google ’em). Of course you lost weight, but this strategy is very unhealthy and totally unsustainable — and it will make you crave lots of food soon enough :)

      Eric wrote on January 27th, 2013
  2. Why go on about eating primal at all? Human digestion, pallate, enzymes, & diet has significantly evolved since man was hunting for food. And in some parts of the world, meat was rare and humans evolved to primarily live on plant, seed & grain.
    Science has proven that we need some carbs to function optimally. Sure we can live without it, but live nutritionally deficient. Just like vegans live nutritionally deficient.

    Don’t forget that fibre, an essential part of our diet, come from carbohydrate sources.

    Simon wrote on January 2nd, 2012
  3. Fascinating dialogue on carbo-load vs Paleo.
    As a once practicing (but not professional dancer,) who frequented professional ballet, modern, ethnic, dancers, it was standard to follow the Steak and Salad diet day in and day out, “working out” all day and late into the night, most nights.
    The “Balanchine diet”, when properly followed, with lots of vegetables, is efficient and healthy long term, when not followed by neurotic individuals. Not exactly Paleo, but add a little butter and bacon here and there.

    Elsie Russell Harrington wrote on January 5th, 2012
  4. I’ve been very low-carb for quite some time now – just over a year, and I can attest that once keto-adapted we do NOT need carbohydrate for our energy resources, IF we eat enough calories.

    There’s many on here saying they had little energy on paleo, etc… which is common when you move to a lower-carbohydrate diet IF you don’t take in enough calories.

    Most studies that compare low-carb to low-fat diets for weight loss also note that the low-carb groups often ate significantly MORE calories than the low-fat groups, yet still lost MORE weight. As such it makes sense that moving from a higher-carb diet to paleo would involve taking in more calories, unless you were already calorie-heavy to begin with, in order to maintain energy output.

    For me I lost nearly 100lbs in a year without any calorie-restriction. In fact, I started at 2,800 calories a day and increased it to over 4,000 because I didn’t have energy on 2,800… Some days I ate over 5,000 calories.

    Most days I ate under 100g of carbohydrate. On my 5,000+ days I’d eat up to 150g of carbohydrate. I was also fueling 5hr+ cycling sessions through the Canadian Rockies on those days… while low-carb.

    Now that the warm weather is gone (and the vast majority of my body fat) I don’t spend 5 hours in the mountains and don’t need to eat as much… I still eat around 2,600+ calories, depending on the day. I often eat under 60g of carbohydrate daily right now. Basically, under 10% of my daily calories are from carbohydrate.

    I continue to exercise (usually HIIT) anywhere from 10hrs a week plus, with no issues affecting my ability to do so, even when eating under 60g of carbohydrate a day.

    But then again, I make sure I;

    1) Eat enough calories, and;
    2) Maintain my Fat/keto-adaptation

    And that’s what makes the big difference for me. Trying to lose weight and fuel activity without enough calories, or while taking in too many carbs doesn’t necessarily work well.

    Glen wrote on January 15th, 2012
  5. So I am new to all this. I have a friend who is a huge proponent and I’ve been at it for a week. Last Friday I was diagnosed with fatty liver disease and my pcp was telling me to cut back on my sweet intake and eat more whole grains.

    I gave him the Steve Austin six million dollar man raised eyebrow.

    As far as excess sugar and sweets, a teaspoon in my coffee or tea, and desserts really only on holidays. As for whole grains and such, it’s the only bread I consumed. So when I told him this he told me to keep at it and just exercise. Well I will admit that I am not the most physically active, but looking at me you would never think I am “dangerously close to clinical obesity”. 5’9″, 208, 34 in waist. No, I’m not in the greatest shape but when I have an image of what obesity is-put there by clinicians-I am not thinking of myself.

    Obviously, I don’t quite buy into all that conventional wisdom. For better or worse, I am a scientist by trade and need to observe, test, and justify things for myself, which leads to my question:

    Where are you getting your research? Not to say what you are saying doesn’t make sense or isn’t logical, but you referenced that the data I’d “piling up”. I am just curious as to what that data is and where I can find it. I am not one to take science lightly. I didn’t believe the moon was tidally locked with the earth, so I did the math to prove it. I was in the fifth grade (point being is please don’t take it personally).

    I have another friend who is a registered dietician whom I’m giving hell. I challenged her to tell me what special thing grains give me that veges don’t. Her answer was “it’s the combination of what you eat with grains that you may not get elsewhere.” so I said basically they are delicious and that’s it, because that is not a scientific answer.

    So, I’m just looking for a little more buyin. :)

    Jeffers wrote on February 3rd, 2012
    • Hi Jeffers –

      Fellow scientist (retired) and equal opportunity skeptic here. Also fairly new to any form of low carb lifestyle, including Primal Blueprint.

      I also have had a similar medical encounter which I am currently sorting through. I don’t eat junk food, drink sodas, consume refined or processed anything, fried foods and so on. I was raised in a health conscious family and raised my own children on home grown organics and grass fed beef, etc. etc.

      To tell someone like us – change the diet to improve health – followed by something like “oh, well, then keep up the good work just cut back a few calories and walk an extra hour every day” is just – what – weak?

      How do fatty infiltrates form in the liver – or other health issues like metabolic syndrome arise – in someone (1) with good genes (2) not taking meds prone to these side effects (3) not eating a terrible diet or (4) lacking in recommended exercise? I EXCEED the exercise and diet recommendations for pete’s sake!

      I hope that Mark responds to your request for more evidence based references. Meanwhile, at this point in my own research – both giving the low carb lifestyle a trial and searching the literature – I have found the answers that my heavily credentialed MD (internist) failed to provide.

      In a phrase – carbohydrate intolerance. Evidently, 3 of 4 people develop carb intolerance at some time in their lives. Health issues follow.

      If you want to read a book based on evidence – written by two of the researchers who conducted 30 of the more recent low carb studies – you might consider:

      “The Art and Science of Low Carbohydrate Living”, (2011), Volek, J.S. & Phinney, S.D. ISBN 978-0-9834907-0-8.

      rarebird wrote on February 7th, 2012
      • Thanks rarebird! I will definitely give it a read!

        Jeffers wrote on February 15th, 2012
  6. Well i was a follower of you until i read this post… Get to low on protein and fat and you will die????? first and foremost, you CANT get to low on protein, you could eat nothing but FRUIT and still get enough protein, mothers breast milk is ONLY 5% or so protein, and that’s the food of humans during there most rapid growth in size. And fat????? the need for essential fatty acids is only like 1% of daily intake. Mark, biologically humans aren’t carnivorous which is what your trying to make it sound like. When children are born they don’t remotely find meat or an animal something to salivate over. I’m sure you know humans secrete CARBOHYDRATE digestive enzymes in the saliva, and our stomach acid is A LOT weaker than carnivores, we don’t have amino acid taste buds, that’s why we have to put a bunch of salty or sweet flavoring on meats so we can taste anything at all, or just because the high level of sodium already in the meat for storage purposes allows taste.. Don’t get me wrong i eat meat, but we were absolutely NOT originally designed to consume it.. The human anatomy tells us that in NUMEROUS ways.. BTW you know that fat just gets converted to glucose or glycogen for fuel right? same as carbohydrates. I have no clue why I posted this comment because I KNOW you KNOW all of what I just said, and a whole lot more, I just don’t know why you are telling people lies.. The only possible way to die from a protein or fat deficiency is to starve yourself by eating NOTHING AT ALL

    Tc wrote on February 7th, 2012
    • Whoa, hold up a minute Tc….Please see my response (above) to Jeffers.

      I agree with you that humans are NOT carnivores much less obligate carnivores. We are omnivores – as supported by plenty of credible evidence. We DO have several evolutionary lineages of amylase – in the mouth as well as the pancreas.

      YET – I agree with what Mark is saying about the relative importance of carbohydrate, protein, and fat. The science that he is basing his statements on – if not referencing – is true.

      In fact, as we proceed through the adaptation phase from carb fueled organisms to fat fueled organisms, our protein requirements increase dramatically. Once we are through the adaptation phase, our protein needs return to the level regarded as adequate for high carb diets. Reason being that during adaptation our ability to metabolize protein temporarily loses efficiency.

      I found that utilizing the food log – as Mark suggests – helps me monitor my protein intake as well as my carbs and fats. I was doing just fine with the fat/carb ratios but needed to increase my protein intake. Doing better on more protein.

      For more of the science, see “The Art and Science of Low Carbohydrate Living”, (2011), Volek, J.S. & Phinney, S.D. ISBN 978-0-9834907-0-8.

      Btw, It is NOT true that human’s don’t have taste buds for meat. The amino acid taste receptors are TAS1R1 and TAS1R3. Meat may be relatively tasteless for some people – as are grains evidently for some people – but as a super taster I can promise you that meat all by itself – raw, semi-cooked, or fully cooked – has wonderful and varied taste.

      rarebird wrote on February 7th, 2012
      • PS. The group of taste buds for meat are the “Umami” buds.

        rarebird wrote on February 7th, 2012
    • finally, truth.

      REW wrote on April 25th, 2012
  7. What about this way of eating for diabetics? I am a pretty active one and was just wondering….

    suzi murphy wrote on February 13th, 2012
  8. Hi.

    All I eat is a bowl of bran flakes with fresh full cream milk and 2 cups of coffee (ricofee, 2x spoons sugar; milk)

    I quit eating bread (both white and brown) Sunday 4 March 2012

    Is that being healthy?

    Deon Fialkov wrote on March 2nd, 2012
  9. I understand the carbs but I don’t understand the fat yet.How do you know how much is good for your diet? How much of your calories on a 2500 day should be fat,how much protein? My husband is trying to lose weight and I don’t want to overdue. I want to get it right. Should he have 20% protein and then what % should be fats. He plays basketball a couple of times a week but is not an “athlete” and does not do any training. And for a woman who does not want to gain weight (I am going along and enjoying this along with him since he brought it up) how do I fit fat into my diet?Thanks for any help!

    joan wrote on March 10th, 2012
  10. I guess what I am looking for is a fat,carb,protein ratio and it is the same for everyone if weight loss is the goal? Sorry but I am very new to Primal and trying to learn ….. :)

    joan wrote on March 10th, 2012
  11. i would agree with more protein and fat diet,and next to not at all carbs,if only not all good nutritionists didnt say that animal protein is toxic for human species cos we evoluted from primates whaic are primarily or even exclusively vegetarians. so what about it? can anyone answer this,please. i am an easy person to switch this very minute to high protein and fat diet cos i am not a sugar lover and i dont eat sugar at all. but nutritionists say brain works on glycose not on fat calories. i believe they know wht they are talking about. and i know a top nutritionists who has been an exclusive vegetarian,maybe the word is vegan,for almost 30 yrs and he is slim. so i am confused. i am rady to switch on protein fat diet and i CAN fast cos i have a strong will and my mood does not drop when i am hungry and hungar passes soon anywhy. but i am worried for my brain and my heart muscle cos i have a heart condition and dont want to stain my heart even more than it is already strained. can someone tell me what to do.i am 64,a female and physically active but i cant work,i only walk a lot. thanks.

    tsahpina wrote on April 20th, 2012
  12. Lots of good info in this blog!

    I’ve been on a very-low carb diet for about 4 months now and have lost over 40 pounds while leaving behind almost all of my former health issues. I also have far more endurance and energy than I did before. My muscle mass is growing. I typically consume fewer than 20 carbs per day, most of those from leafy vegetables and things like peppers and green beans.

    People commenting here generally seem to be cherry-picking and taking a narrow view to support their own experiences and opinions. That’s ok: That’s what people do.

    If you are young and very physically active you can likely consume a carb-based diet and be very healthy. Once you are no longer as active you will likely get fat very quickly on that carb-based diet. It happened to me and many other fitness gods I personally worshiped who are now waddling around in mom jeans now that they have hit their mid-40’s.

    No one is going to be able to come up with a precise ideal diet that works for everyone. Diet is very individualized. But as much as doctors vary in general recommendations for their patients, you likely won’t find a single one of them recommending more refined carbs and sugars. Why? Because refined carbs and sugars make you fat and unhealthy. Now, try to find a doctor who recommends you get rid of all protein and fats from your diet because they make you fat and unhealthy.

    And although I am not a devoted enthusiast of the paleo/primal lifestyle or ethos, I will point out that agriculture itself is a relative innovation. And although primitive humans were not entirely carnivores, they sure as hell didn’t have bakeries.

    Nonplussed wrote on April 21st, 2012
  13. Did you ever think about whether or not the world can economically and environmentally afford to all go primal? Perhaps we should be less concerned with how you can over eat a bunch of meat and instead eat an appropriate amount of a balanced *economically and environmentally sustainable* diet. I promise you won’t get fat if you only consume as many calories as you need.

    REW wrote on April 25th, 2012
  14. A couple of basic questions. What was human’s source of fat 2 million years ago? Or even 10 thousand years ago for that matter? Also, what kind of magic enables cows to create fat from eating plant matter? Think of how the answers to these questions fit into your paradigm.

    Deeds wrote on April 29th, 2012
  15. I was a vegetarian for about 15 years & never ate much meat before that. It’s an emotional/mental thing with me. In the last 3 years I have survived colon cancer & breast cancer + chemo & radiation. As I am now on an estrogen suppressor, I was told to eat very little soy. So I started adding meat back in my diet. I have been SO conditioned to eat grains & fruit, though never ate true junk food. It is difficult to “unbelieve” these teachings & get over the mental part of eating meat. I now also suffer with joint/muscle pain & headaches. Any recommendations? I just want my health back now.

    Sandra D wrote on May 2nd, 2012
  16. Quite by accident I decided to stop all flour and sugar consumption upon moving to a new apartment just for a what the heck it can’t hurt reason. That was October 3, 2011. At one month, I had lost 15 pounds upon a new doctor visit and was shocked. I have continued a loss from 233 pounds (eating healthy, nutritious whole grains foods) to 176.3 pounds today May 4, 2012 (eating protein, fat, and low carb meals). Switched to coconut oil 3 years ago, so most fats are that and olive oil. Dairy almost none, fruit small amount couple times of day, tons of fresh vegies and small amount of russet potatoes and egg for breakfast and some nicely buttered popcorn, small amount for night snack. Yes, those are carbs, but the fat is still melting, so am listening as my body selects what it wants. I’m not just loosing weight, but inches more than weight at this point, but literally feel and see it drop off, sometimes on a daily basis!!!! Had the old lady “hamhock” forearms, that are completely gone and youthful now. Found Mark’s website and am getting good ideas, info and recipes to pass along to others. So far no one has taken up my challenge to see if it would work for them. Their loss – but I love my new way of living — The Primal Diet is for me always!!!!

    Susan Borden wrote on May 4th, 2012
  17. Hi:
    I don’t think the information here is neccessarily correct. It may be for the American diet, but after many visits to Asian countries (mainly Japan,) these are places that eat rice daily. Yes, in small amounts but a couple of times a day. Also, Italy which does eat Pasta daily(also, in small amounts daily,) have lean populations.
    As an aside: My cousin last year went to Italy and Sicily for 3 wks. Her luggage was lost and she had to buy all new clothes to wear for the whole trip. She had to travel to Rome to get an American size 10/12. They did not have her size in any regular stores….I kid you not. By the way she is 1st generation Sicilian. I have been to Italy and they are petite. So my point is it is really simiplist to state that all carbs are bad. I think what happens is we DO eat to MANY unrefined carbs.

    Sweets wrote on May 10th, 2012
    • Where did Mark say “all carbs are bad”? Mark is a runner. He KNOWS when carbs are absolutely necessary to keep energy going during high intensity and long endurance style training, but for MOST of the populace, who are underactive and overweight, eating less carbs (and eliminating refined, processed, GARBAGE carbs) while eating more NATURAL, NON-REFINED fats and proteins to make up the caloric difference (while still retaining a slight deficit below their TDEE but above their basal metabolic rate) simply works in the real world. It’s science baby!

      Eric wrote on January 27th, 2013
  18. How many gram of fat do I need with no starches? My goal is minimum 3000 calories daily! Trying to gain 1 lb lean muscle /week.

    Gabriel Wigington wrote on May 11th, 2012
  19. Can someone tell me if I really need to eat protein every 2-3 hours to prevent muscle breakdown? How many grams fat should a 3000 calorie plan have?

    Gabriel Wigington wrote on May 12th, 2012
    • Yes and no. Anytime you are in a post absorptive yet active state (after eating a meal), your insulin is low and your glucagon is slightly higher. This ratio on it’s own allows for some protein catabolism, BUT every time you eat a meal that raises your insulin, this state allows for protein anabolism. So, your muscles are constantly being slightly broken down and slightly repaired over and over throughout the day. True NET muscle catabolism really would only occur if you were starving yourself for long periods of time. Even fasting up to 18 hours is really no problem as long as you refeed for the other 6 (being sure that they are well balanced meals consisting of both protein and carbs otherwise, in the absense of carbs, the protein will be broken down for energy instead of anabolic muscle repair). On your other question, my OPINION is that you keep your daily fat intake below 130g. for a 3000 calorie diet, this would be a MAX of 39% of calories. This OPINION comes from literature. The info above comes mainly from

      Eric wrote on January 27th, 2013
  20. all this is no big revelation is it? its really just common sense. don’t eat processed foods, sugar is bad for you etc.

    jan wrote on May 13th, 2012
  21. @jan

    to some extent it is common sense, as you say, just lay off the processed foods and sugar
    but wheat? that doesn’t seem like common sense to most people (that i’ve spoken to anyway)
    the majority of people, imo, consider wholewheat to be an important staple of the weatern diet, and to limit it or stop eating it altogether ‘does not compute’ in their minds

    baz wrote on May 14th, 2012
    • baz, I recently read that ancient wheats (as mentioned in religious texts and still can be found today) had twenty-something chromosomes but the stuff today has in the forties. Three of those were not selected for but came about anyway – they induce addiction, pleasure and weight gain.

      The majority does not make it right and the majority does not listen to the needs and reactions of the body as they did in even the recent past. That is where we are trying to travel on a primal diet.

      I found the sugar addiction the most difficult to overcome. It took me three years living in Borneo where high sugary foods were not easily available but within a year I was addicted again upon returning home.

      On a primal raw extremely low carb and 80% fat ketogenic diet, it took but a few months. As a sugar fueler for forty years, I was amazed how easy is was to shed my addictions on this path.

      mhikl wrote on February 4th, 2013
  22. I think you should make mention of the effect of carbs on people with diabetes and those with pre-diabetes or severe carbohydrate intolerance. I have severe carbohydrate intolerance and I keep my carbs at around 20g a day and never go over 30g. Going higher for me means weight gain, carb cravings and over eating and for Type 2 diabetics it would lead to unstable blood sugars.

    I am trying to eat primal but I have to do it very low carb. I restrict fruit to small amounts of berries and I do not eat root vegetables – e.g potatoes, carrots, swedes.

    Diane Smith wrote on May 31st, 2012
  23. Thank you for writing this. I get so tired of people spreading the misinformation about carbs. I’ve been overweight for most of my life. Limiting my carbs has been the only thing that has helped me lose weight and pretty much keep that weight off. On top of that, my headaches, heart palpitations, and depression have gone away. Even nutritionist keep this lie going which I don’t understand!

    Elizabeth wrote on June 5th, 2012
  24. I’m so glad I found you.

    Beki Amador wrote on June 14th, 2012
  25. This is a bit of a late read for me and a late reply to make this comment but there are a few things i wanna say:

    Firstly i don’t see any referencing or any sort of indication that this is anything more than what could possibly be someone playing a practical joke on the chubbier people in the community.

    Secondly, i do like this concept and being very interested in nutrition myself find that it does add up in some unseen ways and open my eyes a little bit as to why we rely on glycogen despite such minute stores in the body when we can retain far more fat for fuel.

    Thirdly, i feel that this is dangerous for a “diet” without exercise as people may begin to look that little bit thinner as in their waist size drops a little and yeah sure, their blood sugar levels will inevitably decrease but their body fat percentage will significantly rise if caution isn’t taken leading to CHD’s, high blood pressure and never achieving that six pack or dropping that “cellulite look”.

    Finally, if you are still working on such a thing, please contact me through e-mail as i am very interested in the article and am currently working on a very extensive database for both nutrition and exercise in relation to BMR and making this work as effectively and easily for any individual wanting to use it.

    I have used the USDA database, am currently importing thousands of exercises to try and incorporate everything i can into it from calories burned turning a page in a book to calories burned when eating a sandwich. My database already includes converters, the food database, individual BMR and a weight loss/gain/maintain system. I am putting in an individual RDA for every possible ingredient in food from Ash to Sodium to make it the most extensive and useful system to date.

    If you would like to contact me about this, i would be more than happy to work with you over the internet to include this “Primal lifestyle” as an option within this database and therefore provide more testimonials for creating the awareness that you are so sure of.

    As priorly mentioned, i have not considered this before and have therefore not researched it which is why i have yet to say if i agree or disagree with it however, testimonials are proving to be a strong case.

    Please contact me on

    Just as an FYI, i have a keen interest in nutrition and have been working towards my degree in sports science since i could with an aim to go into Personal Training, with my interests being in Nutrition i do like to be clued up about it hence the comments and my database.

    Thank you

    Ben Wadeley wrote on June 22nd, 2012
    • Ben W, sounds like a lot of work and it has been done to death the past sixty years. Conventional means haven’t worked so far, so what ever makes you think it will with your efforts. I don’t mean to be nasty; the world has only gotten fatter and sicker following modern paradigms.

      The PB by Mark is more than just this one article and if you spend time reading much of his efforts before judging, then you will have a better education than trying the research path you are presently on.

      Conventional ways to health have not worked over the past sixty or more years. Thinking outside the box is hard for some to do but in these times of cancer, obesity and tired health, it is become the only thing to do when convention means have been disproven by their own failure.

      mhikl wrote on February 4th, 2013
  26. Great informative post if your information was only 50% correct.

    There is more than enough scientific research out there to suggest what you are professing is probably wrong and probably dangerous.

    I agree the sugars, manufactured fructose, over consumed fats/oils and processed food (dangerous mix of everything that is poor in nutrition) could be very dangerous to our health but ‘carbs’ are not the issue when they are from natural plant forms i.e. the potato. The potato is a complete natural package of carbs, protein, fat, minerals and vitamins and any other nutrient deficiencies can be added by eating vegetables, fruits, nuts and seeds.

    What we are missing is that the better the nutrient rich food we eat then the better we are going to be in terms of heath, vitality and maintaining a true weight to support our own individual requirements.

    Forcing our body to run in a glucose deficient state only replicates very sparse times in our evolution and the glucose deficient state of turning fat to energy is a safety net to get you through lean times rather than a way of maintain true function.

    wayne wrote on July 5th, 2012
    • Wayne, conventional research says the only answer to cancer is cutting, burning and poisoning and the first two have been used for over 110 years, the latter uses the same poisons used in exterminations in WWII concentration camps. And year by year the number of people getting cancer in their life times has risen from one in twenty (circa 1900), one in seven (1970) to greater than one in three today and the rate is growing. Fewer than one in three following the three conventions are alive five years after diagnosis. Pitiful.

      PB offers an alternative to the diet and health measures that have made the world fat and sick. The trend is only getting worse following conventional propaganda. And since you believe in conventional research as it now stands, studies are coming out that cancer feeds on sugar, carbohydrates, starch or what ever name you want to call the stuff. High carb foods demand minerals and vitamins for their assimilation and a conventional or SAD diet based upon the USDA pyramid even when fast food is limited (it is acceptable as a part of USDA recommendations), makes it impossible to get enough of these essential elements with out supplementation. On Primal, essential nutrients can be got from natural unprocessed foods high in animal fats, moderate animal protein and low plant based carbs.

      Remember that it is big pharma doing the research; neither the government nor the universities do meaningful research anymore and both are reliant upon big pharma for their monetary support. The fox is in charge of the hen house so thinking people are beginning to put less faith in the medical powers that have failed in their relentless quest to monetize illness.

      Scientific peer review has made it difficult to impossible for true new research and new ideas, (that do not meet the dogma of the day), getting published. We live in sorry times where science has been usurped by the interests of conventional thinking because of the money being made by old, failing norms.

      Less then one in ten can think outside the box. The modern Galileo, Copernicus or Semmelweis doesn’t stand a chance. Incredible that any thinking person would propose gluttony with sugars over measured nutritionally packed foods from animals and low carb plants.

      mhikl wrote on February 4th, 2013
      • >>And since you believe in conventional research as it now stands, studies are coming out that cancer feeds on sugar, carbohydrates, starch or what ever name you want to call the stuff.

        There are more ingredients needed for cancer to become a killer than just a food source. As a human I for one need water and oxygen as a priority!!

        >>Less then one in ten can think outside the box. The modern Galileo, Copernicus or Semmelweis doesn’t stand a chance. Incredible that any thinking person would propose gluttony with sugars over measured nutritionally packed foods from animals and low carb plants.

        There are modern day thinkers and experimentalist proving you are WRONG at this very moment.

        One is here

        Get out of the dogma and learn EVERY aspect to food!

        wayne wrote on February 9th, 2013
  27. This was great. I love that you mention Kuhn. It isn’t often I run across someone else that has read, let alone references his Structure of Scientific Revolutions.

    runnergerl wrote on July 10th, 2012
  28. Mark: You have not listed any references. Could you post them?

    Anthony wrote on August 9th, 2012
    • Anthony, Mark has posted a plethora of references. This is one article; there are hundreds, possibly thousands of references to be found on his sites. What is amazing about Mark’s Daily Apple is that for those truly interested in what is being offered here can read, research and find references and then follow the links in his studies.

      Those who want to condemn with out even trying, have made up their minds and of course won’t bother to take even the time to follow the links in this one page.

      mhikl wrote on February 4th, 2013
  29. I have been wheat/grain free for 4 months and love it. However, I am training for a long distance bike race (100 miles) and I am confused on how/what I should do about carbs? Now, my system is sensitive to wheat products and that could be disaster on my race. Can you help? what should I eat for carbs on long training rides of 3-8 hours and what shoudl I eat during my race? Thank you!

    Wheat Free Biker wrote on September 24th, 2012
    • Once you are fat adapted (using fat for fuel, not carbs) you can train and ride without fueling up on carbs and your endurance should be much better without the ‘bonking’ or ‘hitting the wall’ you can get when you are relying on your body’s limited carb stores for fuel. Fat is amuch more consistent fuel and your body can store vastly more amounts of fat than it can carbs.

      A really good book on this subject is :

      Diane Smith wrote on September 24th, 2012
      • How can you deny human evolution?

        we CAN and SHOULD eat foods that contain carbohydrate i.e. roots, vegetables and fruits.

        ferno wrote on September 25th, 2012
      • Yes, but when exercise increases to the level where your body flips from aerobic to ANaerobic, carb oxidation goes up and fat oxidation goes down regardless. Exercising at increasing levels above 60%VO2max are less than optimal for fat-burning. Also, in the absence of carbs to burn in a continually high anaerobic state, you WILL “hit the wall” and have a hypoglycemic episode (read: collapse) if you don’t slow back down into the aerobic level of exercise which prefers fat burning OR ingest some carbs. Mark knows this well, I am quite sure. References: and

        Eric wrote on January 27th, 2013
        • Unless you are a skeleton, everybody has fat stores for when your body changes fuel sources even if it is 4%!

          Does anyone have real-time experimental data proving when and how your body flips and the definite need to back this up with eating a specific fuel source.

          You DONT need to consume excessive fats instead the natural starches produced by naturaly grown food sources!

          IGF1, change your ways people or you will die before you want to.

          wayne wrote on February 9th, 2013
  30. I love this website. Mark you’re smart man. I will like to get your opinion. Every They I under eat during the day. For about a year. I am also construction worker. And I work out afternoons. I am 6-2 Tall .175 Pounds heavy. I am never low in energy And I don’t have to ever count my calories and I will never come by calories. But I don’t have no problem with body fat percentage. Can you tell me Mark please what do you think about undereating doing today and eating large meal and dinner time. Just my ancestors did it for as long as I can remember.

    warrior wrote on October 2nd, 2012
  31. If you live in a state of ketosis, you will not have the exhaustion problems of carb runners. You don’t have to get a 2nd wind to really run fast because you live in your 2nd wind (in a state of ketosis). You sleep better, and if an older male, you don’t need the viagra anymore.

    Also, there is a lot of illnesses that are yeast generated. I have 8 books that tell you to eliminate the yeast from your sugar diet, and your illness goes away within 4-8 days. Each is repeatable and has not failed.

    Trent Black wrote on November 29th, 2012
  32. “Glucose is not the preferred fuel of muscle cells under normal human resting metabolic conditions or even under most normal human movement patterns (exercise)”

    You must be kidding…What’s your evidence for this claim?

    jay beck wrote on December 12th, 2012
  33. What would be the Grokkers opinion of taking a male who is slightly overweight and wanting to lose fat but also bulk a little? Should he start with one ratio to shed fat and then a different ratio to bulk some? He doesn’t want to be super bodybuilder type, just a more muscular physique. Thanks in advance for your help!

    Linz wrote on February 6th, 2013
  34. I just thought I’d add that another thing to also consider is the density of fats vs carbs. The way our body is structured (in the intelligent way that it is) it stores fat more than carbs considering fat is approximately 9kcal/g while carbs are about 4kcal/g. That should light some bulb that if our body is built to store fat that maybe it’s a bit more important than glucose. I really like what you have mentioned and even as a kid, growing up in Ukraine where most people had a super high fat diet, I noticed how healthy people were and the long lives the people lived. There was no way you convince me carbs > fats. Anyway, great read thanks :)

    Dmitro wrote on April 9th, 2013
  35. Eating a certain number of carbs per day won’t lead to weight gain if energy out > energy in. Think about it. Thermodynamics.

    By the way, “preferred fuel” isn’t synonymous with “only fuel”.

    Further, ingested carbohydrates are converted to fatty acids via exiting the Krebs cycle, so tissues that like to use fatty acids get them from carbohydrates. It’s why glucose metabolism is the central pathway that all other metabolic pathways converge on.

    Christine wrote on April 9th, 2013
  36. I agree 100%, and it’s been my experience regarding carb vs fat intake. But what about those crazy vegans like that nut Durianrider on YouTube, who recommends 10g of carbs per kg (or was it LB?) of bodyweight, lol. He’s a skinny runt and insists a high carb vegan diet gets you ripped. Now, he is a high endurance athlete… but I’m sure genetics must play a role as well, because there is NO way I could get skinny eating like him, even if I ran 3 hours a day. Thoughts?

    Josh Hewett wrote on May 21st, 2013
  37. What a great article! Such a shame that so many people believe all the lies regarding nutrition and happily consume too many of the wrong foods day after day.

    vic wrote on June 16th, 2013
  38. I’m revisiting MDA after a two year ‘voyage autour de ma ‘chambre’.

    Anyhow here goes:

    I think 150g of cho is quite reasonable and seems like ‘high carb’ for some people. So it’s fine.

    I do like to note that to argue the logic of ‘there is no essential dietary carbohydrate as there is essential AA and fat’ that carbohydrate contains the word ‘hydrate’. That is important and should be remembered. They are important from that aspect, but meeting 150 g worth certainly achieves the ‘hydrate’ aspect.

    I have a second question: I know the Kitavans (and I hate to point out to a group whose life style does not approach our lifestyle) are noted to eat lots of cho. I know they also don’t eat all these grains and sugars though. But is it b/c they IF naturally, work a lot (?) and also they smoke a lot? I’m particularly asking about the relation to their nicotine intake and it’s relation to their level of cho they can tolerate. I’m not trying to defend them nor to bash them. I’m just interested in this fact. Similarly how the French tend to smoke a lot, but for them it was the sat. fat aspect that people noted how they were healthy despite this. (They do enjoy their sweet pastries though).

    Mark I am interested in your take on the role of nicotine.

    Thanks, it’s great to be back at this blog after 2 years.

    Zorica Vuletic wrote on July 12th, 2013
  39. Sugar is the cleanest burning fuel for the body. The obesity epidemic is caused by PUFA, endocrine distuptors, and starch plays a role.

    You can safely over eat on carbs and protein by 2-3x caloric need before de novo lipogenesis occurs. Fat will be stored when caloric need is met. Therefore I support the idea that body fat is simply an accumulation of dietary fat in the tissues.

    Eat less fat, eat more carbs. Eat most fat in the morning, along with protein, and sugar to jump start the metabolism. Support energy production in the body.

    Energy should come from nutrient dense foods – fruit, milk, liver, grass fed whenever possible. Grains, starches, non-saturated fats should be minimized.

    Richard wrote on August 8th, 2013
  40. Interesting post. But what is PB?

    Tran wrote on September 4th, 2013

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