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. Vitamin C is a nutrient absent from meats and vitamin B12 is a nutrient absent from plants.

    If you went on an all plant diet, you would get a lot of vitamin C, but no vitamin B12 and then die.

    If you went on an all meat diet, you would get a lot of vitamin B12, but no vitamin C and then…still live.

    Vitamin C is a non-essential nutrient, the body can do fine even without it. Vitamin B12 deficiency is a terrible thing.

    Ricky wrote on December 5th, 2011
    • Not so. Inuits ate fermented animal products and suffered no effects from vitamin c deficiency. I’ve even heard that the skin of seals is rich in vitamin c, but I cannot remember why. Fermenting foods, which most meat-rich cultures does, ups the vitamin content of meats.

      Ann wrote on June 6th, 2012
  2. A dietitian once told me I was making a bad decision by not eating any desserts because NOT eating desserts is a BAD thing because once I get the chance to eat it after a long period of abstaining from it, I will end up binging on desserts.

    That’s like saying to an addict that NOT smoking or doing drugs is a BAD thing because once he or she gets the chance to do it after a long period of abstaining from it, they will end up binging on illegal and harmful substances.

    This comment of mine was made possible by Noel Dibish, RD, who is an overweight dietitian and is apparently one of the “top” dietitians at Kaiser Permanente (Union City, CA branch I believe). She also says that high-fructose corn syrup is “not that big of a deal”, and that getting fat or losing fat is a simple matter of the foolish “calories in vs. calories out” concept. Thanks but no thanks, I’d rather have my dessert-free healthy body with some grains (not 9-11 servings like the way you advocate) to match my low physical activity level than to have your body with a ring of carbohydrate loaded fat cells and intestines full of putrefying junk. If you want to spent some “quality” time at a “hotel” full of people in white coats, follow this dietitian’s advice and you will have her to thank in no time.

    Now without further ado, I have a bowl of white rice to eat and a ricks

    Peter wrote on December 5th, 2011
    • haw to haul.

      Peter wrote on December 5th, 2011
  3. A dietitian once told me I was making a bad decision by not eating any desserts because NOT eating desserts is a BAD thing because once I get the chance to eat it after a long period of abstaining from it, I will end up binging on desserts.

    That’s like saying to an addict that NOT smoking or doing drugs is a BAD thing because once he or she gets the chance to do it after a long period of abstaining from it, they will end up binging on illegal and harmful substances.

    This comment of mine was made possible by Noel Dibish, RD, who is an overweight dietitian and is apparently one of the “top” dietitians at Kaiser Permanente (Union City, CA branch I believe). She also says that high-fructose corn syrup is “not that big of a deal”, and that getting fat or losing fat is a simple matter of the foolish “calories in vs. calories out” concept. Thanks but no thanks, I’d rather have my dessert-free healthy body with some grains (not 9-11 servings like the way you advocate) to match my low physical activity level than to have your body with a ring of carbohydrate loaded fat cells and intestines full of putrefying junk. If you want to spent some “quality” time at a “hotel” full of people in white coats, follow this dietitian’s advice and you will have her to thank in no time.

    Now without further ado, I have a bowl of white rice to eat and a rickshaw to haul.

    Peter wrote on December 5th, 2011
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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

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