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. Great article. I remember this from your book, which i truly enjoyed reading.

    Antwone wrote on May 20th, 2011
  2. I’m on the primal/paleo bandwagon, but there are still a few contradictions in the carbs arguments that bother me.

    1. This in depth, study-backed analysis of insulin makes a good argument that simple overeating, not carbs themselves is what leads to people being overweight.

    2. Looking at our closest evolutionary relatives, non-human primates eat tons of fruit nearly year round. Lots of carbs, but no weight problems. It seems likely that humans would be similarly adapted for lots of fruit.

    3. If the body burns fat so preferentially and efficiently, why can’t it be tapped for long-distance events like a marathon? lt seems like a contradiction to say that fats are such a great fuel, but actually if you’re a very physically active person fats won’t do and you have to go back to the carbs.

    Would be great if you could elaborate on these points in your next post.

    Brian wrote on May 20th, 2011
    • “3. If the body burns fat so preferentially and efficiently, why can’t it be tapped for long-distance events like a marathon?”

      I suspect the only reason our very ancient ancestors ever ran 26 miles was if they encountered a hungry sabre-tooth who was willing to go 25.

      Todd wrote on May 20th, 2011
      • More likely they were chasing dinner which would only run 25 miles. We lost our body hair to keep cool in those strenuous situations.

        gen wrote on May 21st, 2011
    • Our “primates” have the hip structure of a dog, it’s tilted forward and they have a hard time walking up right.
      Also their digestive tract is a lot longer than ours. They also lack a tiny bone in the feet to accomodate walking upright.

      Primates are not our relatives. They’re a species all of their own.

      Primal Palate wrote on May 20th, 2011
    • That weightology analysis sounds like a person who really wants to believe something, rather than one with a complete picture of the processes (not that anyone understands the body completely!). Read comment #10 by Matthew.

      I’m not sure what all the fuss is about a marathon – I’ve done a 1/2 and it was awesome to see I could, but it has no practical application to my life. Just because I could push my body to eat grains or run 13 miles at a time does not mean it’s good for it.

      Heidi P. wrote on May 20th, 2011
  3. I’ve been eating paleo for 10 days! I feel great but I do get light headed by afternoon. Not sure what I’m doing wrong. I follow and use recipes from cookbooks. If I eat some fruit with nuts I feel fine after. I’m afraid from reading these comments I’m eating too much fruit (usually 4-7 different fruits a day). I do love fruit! This article is great because since I’m a newbie to this lifestyle I have been getting a lot of concerned questions and comments about my grain intake. I can’t find any support in my town they think no grain eating is only temporary. Are they right?

    Lisa wrote on May 20th, 2011
    • Don’t be afraid to eat that much fruit if you are in the transition to a primal diet.
      At the beginning I used to eat a giant bowl of blueberries a day + 2 bananas and raw honey.
      It’s tapered off slowly. After a year and a month of being primal I now only eat 2 servings of fruit a day.
      Nuts and chocolate seem to trigger sugar cravings in me, not sure why, so I ditched those 2 things from my diet long ago.

      It took my body about 6 months to hit homeostasis.

      Primal Palate wrote on May 20th, 2011
      • Thanks, that helps me feel better! I had just read all this again and had a conversation with some one right after about not being able to eat Paleo while participating in Crossfit. Anyone have any info on this?

        Lisa wrote on May 20th, 2011
        • I can’t speak for them but my story was like this:

          Starting Primal I made it to week 3 and then completely lost it. I HAD to HAVE grains and sugar so I binged on mexican pastries for 3 straight days with no solid meals. After the 3rd day I felt miserable…it was BAD. I remembered how great I just felt for 3 weeks before going nuts from my cravings because I was days from my period.

          The next month was slightly better…I made it to the 3 weeks again and only indulged 2 days into mexican pastries but less of them + primal meals.

          By the 3rd month I had sworn myself I’d pay attention and ‘beat it’. Things didn’t really get any better until I found a farmer that sold raw goat milk.
          The raw milk had something in it that completely killed all my cravings for sugar and grains, chocolate and nuts.
          Another 2-3 months or so passed and I hit homeostasis.
          Now, while I was transitioning (and it took a loooooong time it seems) I had absolutely no desire to work out. I had no endurance whatsoever. I coulnd’t even sprint. I was nutritionally so crippled that my body took all its energy to rebuild my ‘crippled’ body back to life. I even had to start taking afternoon naps!!! It desperatly wanted to heal and I gave in.

          About 10 months or so into it I finally didn’t need naps anymore and I felt like sprinting and lifting weights.
          I now joined a gym (4 weeks ago) and I’m lifting heavy things and do my sprints up and down the stairs, I refuse to be on a treadmill. I’m starting to get some really nice muscles, I’m the only girl in there with biceps :-)

          So you see, if someone just switched to primal, the body might not want to be using those precious nutrients for work-outs, but would prefer to heal first.

          Primal Palate wrote on May 20th, 2011
        • Paleo/primal lifestyle and Crossfit go hand in hand. At my Crossfit box, we try to encourage people to go the Paleo/primal lifestyle. Those who do find their times and scores for all WOD’s get better after only 90 days.

          Bull wrote on May 22nd, 2011
        • Finally! Some one answered my crossfit question! Thanks so much, I think I’m going to stick this out. I have not worked out and went jogging today ( I don’t run or jog) and I felt awesome! I have never felt so good attempting to jog. I ran longer than I ever have without feeling out of breath or exhausted! My dog was tired out before me!

          Lisa wrote on May 22nd, 2011
  4. This is my favorite post in my year of checking the apple daily. And THAT is saying a lot. It is concise, educated and true on a fundamental level. Plus the embedded humor makes it fall in the play category. I’m so grateful for the important work that you and your staff are doing for our communal health. Here’s to the truth setting us free and here’s to Grok raising the cognitive dissonance stick against the mainstream.

    Sally wrote on May 20th, 2011
  5. And this is exactly why I’m returning to school for a BS in Exercise Physiology and Nutrition – to change the system from the inside.

    Thanks as always for a most informative post Mark! I send people here first when the topic of diet comes up.

    Jesse wrote on May 20th, 2011
  6. Thank you Mark. Superb post!

    All this is such a huge paradigm shift so difficult to explain to our friends and family.
    Sometimes I feel I´m being regarded as some sort of fanatical Taliban when trying to explain it.

    It is incredible how difficult it is to even give it a chance, the benefit of the doubt!

    Sometimes I think we are like Columbus explaining that the earth is not flat.

    Jose Zeballos wrote on May 20th, 2011
  7. Part of the brilliance in being human is that we can adapt and even thrive on a wide variety of macro-nutrient ratios.

    It is folly to think that a single ratio is correct for a certain individual. I would bet that anyone could adapt to a reasonable ratio falling predominantly into any one of the big three (carb, fat, protein) and be healthy.

    High protein, High Carb, High fat, you name it, someone’s lost weight on it and improved their health markers. You can find past and current cultures that thrive in any of these categories.

    Unfortunetly we cannot find any culture that thrives on nutrient deficient industrialized garbage that make up the typical SAD diet…

    Monte Diaz wrote on May 20th, 2011
    • Exactly!! If this is the case, why the demonizing of starches and insulin by the paleo community? Why does the default position of the paleo/primal “blueprints” and “solutions” etc have to be low-carb when there is vast evidence of high carb eating ancient societies?

      David wrote on May 20th, 2011
  8. It never ceases to amaze me how much backlash comes with the recommendation to control carb intake. I suppose this can be explained by how they are supposed to have an addictive effect. Its too bad that more people dont just try Marks recommendations instead of continuing the path they are on.

    robertbarnes3 wrote on May 20th, 2011
  9. The human body is adapted to eat a varied diet out of necessity. In my opinion this doesnt prove that we can either function optimally eating high carb OR high fat.

    robertbarnes3 wrote on May 20th, 2011
  10. Thanks, Mark! I will be seeing you on Wednesday in New York for the Q&A on just this subject, and this got me even more fired up to go!

    Justin wrote on May 20th, 2011
  11. THANKS MARK – this REALLY helped me. But could you use some more sources? Some claims you made like “your body runs on fat not glucose” I could not find backed up by a scientific explanation, if you know what I mean.

    Meagan wrote on May 20th, 2011
  12. Ancient societies eating high carb are NEOLITHIC..we’re going back a little more in time to Paleolithic..which is higher fat and lower carbs…HOW many of you know the difference?

    DAVE PARSONS wrote on May 20th, 2011
  13. PB has worked wonders for me and I’m a true advocate. I have a dirty little secret though…I love carbs. I know, I know. I should go scourge myself right now, but I just can’t seem to kick cereal. Probably one of the worst things I could eat.

    I have seriously minimized how much I have though. I’d say about 80% of the time I’m under 150 grams of carbs a day.

    Trey wrote on May 21st, 2011
  14. My weight loss coach has me really watching my carbs. I went off sugar which was really really hard for me. But she lost 100 pounds eating 6 small meals. Being in her 40’s I read about her on-line saw her before and after photos and thought why not we are the same age and I have to get weight off per dr orders and wanting to be here for my 5 kids. Jill has been a great support. You really actually have to see her before and after photo to understand what I am talking about. she is at
    Your information is great. Thank you!

    Havannah wrote on May 21st, 2011
  15. Excellent post on the metamorphosis we all undergo by following the PB! Explaining the reasons why a glucose metabolism is so detrimental to our bodies for the masses that continually buy that failed logic is paramount. Thanks for putting it layman’s terms for all, Mark.

    nachobrawler wrote on May 21st, 2011
  16. Why is there no email link for forwarding articles to others?

    Alex wrote on May 21st, 2011
  17. I would say that generally speaking this is a great advice for normalizing and improvings one`s metabolism.

    Perhaps there is a bit too much preferance on fats but that can be understood in the light of oppostion to general public dietary guidelines.

    But – it is very important that BOTH fat and glucose metabolisms are functioning AT THE SAME TIME. This cannot occur when one isn`t adapted to efficient fat burning.

    Rejecting fat or carbs (which is not the case with PB – 100 to 150 grams average of starch and sugars from fruit seems very appropriate for the majority of people) can be dangerous and can severly damage one`s health.

    Bostjan Remyc wrote on May 21st, 2011
  18. How long is it supposed to take before your body starts working normally again after you go PB? I’ve tried PB/LC a few times for a few weeks at a time, but always had to cut it short after I ended up with severe brain fog and absolutely no energy (and severe sugar cravings). And I wasn’t even very low carb at around 150g a day.

    My heart also beats extremely hard when I eat a lot of meat. This feels scary and makes it almost impossible to sleep. It goes away once I eat more carbs.

    ‘Primal Palate’ wrote that it took her many months of PB to reach homeostasis. It would be great if others could share their transitional experiences as well.

    Don wrote on May 21st, 2011
    • You will experience brain fog and lack of energy. This happens while your body adapts. You have to get past that.

      wozza wrote on May 21st, 2011
    • Hey Don,

      It took me a few weeks of feeling REALLY poor then a couple months of slowly feeling better day by day. I didn’t get that “wake up one morning and feel awesome” thing like I see a lot of people write about. I’ve been primal for almost a year now. I’m almost 40 and feel better than I did when I was 21. Seriously.

      I feel your pain though, sugar withdrawal is just plain not fun. Bacon helps a lot, don’t be shy with it.

      Desert Caveman wrote on May 21st, 2011
    • Don’t worry — it happened to me too. There is no need to push through it… every time I got scared from being so foggy I went to Taco Bell and had 3 tacos and a pop. I was thinking things just weren’t going to work out… Well the taco bell trips ended up being further and further apart, from every 3rd day to every other week… and now I haven’t been there in a month and I’m totally fine on like 50g carbs today. No suffering through mental fog to make it here. Just persistence with returning after my Taco Bell breakdowns.

      justin wrote on May 23rd, 2011
  19. Mark,

    I feel like there’s much evidence to the contrary that there is any one preferred macronutrient fuel for the human body.

    Dr. Guyenet has shown several examples of healthy high-carb cultures. In populations not predisposed to metabolic disorder due to their whole foods and traditional diets, perhaps lots of starch is fine.


    Colin wrote on May 21st, 2011
  20. HI..Has anyone here ever heard of Charles Darwin? He had a theory about location and evolution..
    I’m pretty sure that where we live and the generations of our Ancestors in these locations…along with the food they ate and eat is why cultures in different ares of the globe can consume different foods and thrive…America is very young and the people are from everywhere…and this Agro-business diet has shown that we are some of the most messed up…
    I eat tons of fat and very few carbs and am strong as an ox..can go for days without much food at all…and have noo problems sleeping or eating or thinking…I am PRIMAL/PALEO shows very clear to me..So do yourself a favor..MANAGE this..keep track of your food intakes..It is SIMPLE diet-exercise and a way of life you can tune for you to be in the best health and eat well and live well…EVERYONE is different..find your slice of the Primal life and live it..GROK ON>>>

    DAVE PARSONS wrote on May 21st, 2011
  21. What’s the level below 50 grams of carbs called, Keto/ I.F. mean?

    Bruce wrote on May 21st, 2011
    • Bruce,

      Generally speaking when you consume 50 or less carbs per day your liver runs low on glycogen and starts producing ketones. Ketones are made from fat. This is why people talk about being “fat adapted”. It is the process of “weaning” your body from using carbs to using fat for fuel. The liver will also produce glucose from free fatty acids in a process known as gluconeogenesis. This is a beneficial state because it burns fat AND the conversion isn’t efficient so it has to use a lot of fat to do it.

      I.F. stands for Intermittent Fasting. A daily 20 hour fast would be considered intermittent and would definitely help you get into ketosis faster.

      Monte Diaz wrote on May 21st, 2011
  22. To the poster who made the comments about paleolithic vs neolithic “ancient” societies….does it really matter?

    We live in the present and adaptions have taken place whether or not your inner “grok” wants to acknowledge it or not. We have 8 times the concentration of amylase in our saliva than apes. Guess what, this is irrefutable evidence that we’ve adapted to eating starchy tubers. (Carbs!) And not just a few either…

    Like I said earlier, you can find a culture that has thrived on a diet falling predominantly into any one of the big 3 macro-nutrients.

    So can paleo be low carb? It can. Can paleo be high carb? It can. We need to remember that paleo is a “time period” not a “diet”. Diets have been and will always be varied. The only thing unavailable in the paleo time period is the industrialized processed garbage that makes up the majority of the SAD diet.

    Monte Diaz wrote on May 21st, 2011
  23. One of the proofs given to me that obesity causes T2 Diabetes is that 45% of diabetics are overweight or obese. Well then, that should prove that slenderness causes diabetes too, because 55% of diabetics must be either the right weight, or slender.

    Bill DeWitt wrote on May 22nd, 2011
  24. Could someone give concrete examples on what the different levels of carbohydrate intake would look like? I don’t have any concept of what a gram or 50 or 150 grams of carbohydrate a day would look like. How many grams carbohydrate is fruit?

    Ruth wrote on May 22nd, 2011
    • Go to it’s free and tells you all that info!

      Lisa wrote on May 22nd, 2011
    • For example:

      1 banana = 7g sugar + starch (complete 10g)
      1 small apple = 5-7g sugar
      1 serving Berries = 5g sugar

      Total sugar (carb) consumption coming from fruit = 20-25g

      Do not consume more than 20-30g of total fruit sugar in one day.
      Approx. 2-4 servings of fruit a day.

      That’s on top of having liberal amounts of vegetables 2x a day with your main meals and perhaps a handful of nuts.

      You’d total about 50g – 75g of Carbs a day.

      1 cup of Raw dairy is about 11g I think.
      When choosing Yogurt pick one that’s plain.

      Primal Palate wrote on May 22nd, 2011
  25. As a truck driver I often stop at convenience stores for snacks during my work day. About five years ago I noticed that I was losing weight without really trying, a good thing since I was packing around an extra 30 pounds. Now whenever I put back on those extra pounds I go back to what worked before. A low carb but filling snack of “pork rinds”. Limit my beer and bread intake along with more pork rinds and pounds begin to go away.

    Darc wrote on May 22nd, 2011
  26. Mark
    Again, another great post! I bookmarked it so that I can e-mail it to some workmates.

    They look at me so curiously when I do stuff like scrape the toppings off the pizza (I am not gluten-intolerant), or take a lunch sandwich and scrape the meat off and throw away the bread (you know – the crap that they feed you when you have a lunch meeting)! (lol)

    You are going to not like this, but, I am having some success by uptaking my carbs through a banana and raw legumes/vegetables (5 days/7 for lunch). I know you aren’t freindly towards legumes, but those raw snap peas (or garbanzo beans when I treat myself) are so yummy!

    Evenings (when I can get it down) and weekends are meat-centric (if I even eat at all).

    It isn’t just that I like my vegetables raw (taste matters!), it is also that it is my enzyme replacement therapy. And for enzymes, the food must be raw (below 104 degrees). High enzyme and flora lead to a healthy immune system.

    And despite a fairly sedentary lifestyle (not enough high intensity work) (retired Ultimate disc & 10K racer), I am still getting a fair report from the doctor, to wit:

    – triglycerides 44,
    – LDL just above the optimal level, but particle size is large,
    – could lose about 10-15 lbs (of fat), but also would need to add about 10 lbs of muscle to be in the “sweet spot”

    Just a note, I know how much you disdain legumes, but I thought you might be willing to hear an observation of how that is working out. Maybe? Where you get your carbs does matter? I don’t know – it is something that I am still confused about…

    Iluvatar wrote on May 22nd, 2011
    • I forgot to add. I also eat a lot of peanuts (yeah, I know, yet ANOTHER legume!). Peanuts w/ skin on b/c of resveratrol (beats red wine or grape skins!). I mix it in with other nuts (pecans, walnuts, and cashews).


      Iluvatar wrote on May 22nd, 2011
    • You sound like an old fart with a stubborn brain, and you are paying wayyyyy too much attention to individual nutrients. You do realize that there are hundreds of nutrients in food, right? Nutrients that have yet to come out with fancy names and studies? Buzz off.

      George wrote on October 22nd, 2011
  27. Wow, That was a really good post. Even though I am in Fitness, I don’t restrict my self of things at all carbs or fat as long as I am eating healthy foods. Years ago I tried cutting down on carbs but I couldn’t work out as intense as I liked. Now I just try to listen to my body, if I feel I need to eat carbs I do, and If I feel I need to eat something with fat in it I do as well. Thank you for a great post

    Tatianna wrote on May 22nd, 2011
  28. When I changed my eating life style to meat and veggies and a few fruits, I found I have a hard time getting to 100 grams of carbs a day, let alone 150 grams.

    Bull wrote on May 22nd, 2011
  29. What I’ve found is the main problem with any lifestyle, be it paleo, vegan, vegetarian, is the holier than thou attitudes. Even in this post, everyone’s like, “This is sooo obvious! Why doesn’t it anyone get iiiiit, everyone else is so duuuumb” (I’m paraphrasing; stay with me!)

    The low carbers think they’re right. Vegans think they’re right. Vegetarians think they’re right.

    Lot of references to the average American. What about thin non-Americans? Someone who eats moderate fat, moderate carbs and protein in “standard” ratios of 40-30-30 and doesn’t have weight or health problems?

    A girl can run herself ragged trying to find the right thing to stick with. I’ve flirted with vegetarianism. Couldn’t do it. Won’t even touch veganism. But I’ve never liked meat, so what to do? I like chicken, but I can only eat so much of it before it gets boring, even with a multitude of recipes on hand.

    I don’t believe in very low fat (wtf, at 80/10/10!??) Never again. But low carb also makes me feel like shit, too. Could I get some general guidelines on increasing according to activity? Please don’t ask me to experiment. Being as lean as I am, I’m afraid to experiment and lose weight (be it muscle OR fat), but I’m having a hard time finding a good balance for maintainence.

    Lisa wrote on May 22nd, 2011
    • Hi Lisa

      I think the balance is the key. Like you I have tried being a vegetarian, I also experimented with cutting carbs, but nothing worked for me a well as a simple balanced diet. I don’t like restrictions, but I also eat pretty healthy due to my eating habits growing up. I have to say that I am very lean, and I believe I got that way by not restricting food groups.
      All though it is bad to over indulge on complex carbs, such as white bread, rice or pasta. But fruits and veggies, I eat in crazy amounts.

      Tatianna wrote on May 23rd, 2011
      • Sorry, I made a mistake, When I said complex carbs I meant to say Simple Carbs. Sorry made a mistake.

        Tatianna wrote on May 23rd, 2011
  30. @Lisa — “The low carbers think they’re right. Vegans think they’re right. Vegetarians think they’re right.”

    Yeah, well, that’s the nature of religion. Or the “belief engine” that Tom Naughton talked about on the 4th Annual Low-Carb Cruise. I have had fantastic results from low-carb, but it’s not the answer to life, the universe, and everything — there are still pieces of the puzzle missing. It’s not settled science.

    I’ve been blogging about my own low-carb journey at These days, I’m tending toward low-carb paleo, except that 50-100g/day is not really low-carb. I’m thinking of it as “right level of carb” at least for me, and the SAD is just ridiculously high-carb (with a boatload of HFCS).

    When I went low-carb in 1999, I avoided the “Atkins Flu” by keeping a detailed diet log for a few days to establish a baseline, then cutting back gradually over a period of a little over two weeks. The feel-bad period from cutting back on a really high-carb diet is about the same length as the feel-bad period you get from quitting smoking, and I suspect it’s pretty much from the same cause — breaking an addiction.

    Howard wrote on May 22nd, 2011
    • @Howard – whoa, chopped a part of my comment off before posting. That’ll teach me to not proofread…

      What I meant to say was, those have worked for a lot of people. So to say flat out that vegs are totally off the mark is a little unfair. Though I have to admit a lot of the vegans I know are either overweight, sickly thin, or just sick all the time because of low immunity.

      But if a person is reaching their nutritional targets, does it matter if they do it with a lot of veg, fruit and tofu and not a lot of meat?

      Vegetarian is failing me now; carbs aren’t really an issue with vegetarianism, but fat is! I’ve had to up my fat intake because I was, like a lot of other veg women, getting irregular cycles before they stopped entirely.

      But daily, I pretty much get around 130-150 g of carbs daily. I haven’t gained or lost weight, but I know when I’m on the lower end of things, I don’t always feel well. So it doesn’t sound like a case of breaking an addiction to carbs.

      Lisa wrote on May 23rd, 2011
  31. From what I get to hear a lot..Im never right..LOLOL Life itself is an experiment …Im afraid we all have to experiment ..for there is nothing written that pertains to us all…GROK ON>>> however you do it…to each his or her own…And dont forget the Bacon…

    DAVE PARSONS wrote on May 23rd, 2011
  32. I could not DISAGREE more. High fruit, LOW fat, raw vegan diet is the way to go if you’re looking for not only a lower body weight but also vitality and stamina. Read Douglas Graham’s book 80-10-10. This high fat diet you’re promoting is just giving people an excuse to keep eating animal products, which are high in saturated fats and cholesterol, not to mention antibiotics and growth hormones. You can throw scientific data and any diet, but to claim this is how humans are SUPPOSED to eat is riiiiidiculous. Humans, before all our conveniences had to find food to eat. That was mostly fruit. Look at the way anthropoid apes eat (these animals are closest to humans.) Very high carbon diet (fresh, raw fruits and vegetables.) Less than 1% of their diet is comprised of insects/rodents. Pound for pound, they are 5x stronger than humans and have no real need to even drink water since all the water they need comes from the raw fruits and veggies they’ve been eating all day. I’m sad at the number of people who read his article and now feel enlightened.

    Sunny wrote on May 23rd, 2011
    • Sunny: I’d suggest taking in a class in either biology or botany. A diet consisting of mostly fruits would mean to starve in any northern states. Ever eat Peaches in January in Ohio? Or how about fresh cherries in October?

      Oh, and bananas don’t exist in Michigan. 4million years on this planet walking upright was not because of your of your “riiiiidiculous” enlightenment experiment. Go get all hippy on some other zen internet forum.

      Daniel Merk wrote on May 23rd, 2011
      • I wonder if the “fangs” we have are for something else… because I have seen the show about Chimps hunting down and eating other primates..
        And …there sure are a lot of fruit trees out on that African Savannah and up in northern Europe….we GROK ON>>>

        Daveman wrote on May 23rd, 2011
    • Sunny, did you know that you could not find a fruit like you know 10,000 years ago? Nor could you find most of your favorite vegetables. The fruits you think apes eat are mostly bitter, hard and small compared to the “candy on a tree” you may be used to. Secondly, look up the behavioral changes that enabled our fuel hungry big brains, the literature usually mentions breaking bones for marrow and cracking skulls for brains. That’s all about the fat. I was a vegan for 35 years and it almost killed me the last ten. Returning to an ancestral diet saved my life.

      Bill DeWitt wrote on May 23rd, 2011
    • So we used the spears and arrowheads to reach all those apples and cherries on trees.
      I guess I could get good at throwing arrow heads at a berry bush…it would take a lot of practice though.
      All those american indians that killed all those precious animals just for their fur (hmm, reminds me of something).
      And all those eskimos that kill all those fish for thousands of years to try and rid the ocean of its ‘pests’…those darn fish just won’t stop coming back, will they.
      And the primitive australians killing kangoroo for the flesh, errr I meant fur…

      No, we did not evolve eating meat at all…I guess non of these cultures got your Memo…eh?

      Primal Palate wrote on May 23rd, 2011
    • Sunny, I got sick from trying to keep my fat that low. Yes, even with higher carbs. It worked for awhile but I found it impossible to sustain.

      Fruit and veg are awesome and I love them, but I really disagree with 10% fats. When I was keeping my fats at 20-25g daily, I was cold and irritable all the time. I was underweight because the drastic cut made me lose a little, and I never needed to in the first place. I was weak to boot, which was the worst, because I’m normally athletic.

      I’m not saying you need to go and eat meat, but once I played with the fat intake a little, I felt a million times better. I just make sure 20-30% of my calories come from fat now. Little extra olive oil, more tofu or tempeh, anything helps.

      Lisa wrote on May 23rd, 2011
    • Chimps strenght is their downside. They can’t make delicate, precision movements, necessary for advanced tool making. They are also horrible throwers. This is because in chimps a small number of neurons controls movement of large number of muscle fibers. This gives an easy way to get 100% of muscle strenght utilized by firing a limited set of neurons, but means no fine control.

      Humans are supposed to be selected for having a large number of neurons thanks to the requiements of hunting by throwing. Throwing has accuracy requirements that grow with distance, and unlike in moving across the trees there is no possibility of last-milisecond corrective movement.

      Tomasz wrote on May 24th, 2011
    • No. And I’ve read that back in the primal days, fruit as we know it was not easy to come by. The fruit you see today was all modified and selectively bred.

      And I would strongly caution eating massive amounts of fruit unless you can point to a study that shows the body handling the sugar from whole fruit differently from refined sugar.

      Fructose greatly accelerates glycation.

      George wrote on October 22nd, 2011
  33. Daniel Merk… Hippy police. I have too little time this morning to go into eating what’s in season and remembering humans didn’t start out in cold climates such as the Midwest. I would like to recommend the book titled, “80-10-10” for anyone looking to be UNbrainwashed by the meat and dairy industries… or maybe you could read it for the sake of playing Devil’s Advocate.

    Sunny wrote on May 23rd, 2011
    • So it looks like more meat for us……dont forget the bacon!!!!
      Your talking to the wrong crowd here…go talk to a vegan page…we have more books than your one …and they are written by PHD’s and others who have done the homework… forgot to say”organic”
      if your so TUNED into that routine…

      Daveman wrote on May 23rd, 2011
    • Sunny, your theories on your vegan experiment/spirituality movement doesn’t interest me. Was a vegetarian for 10 years and was tired of being sick. Good luck with your experiment. We’ll see ya in a few years when your bones break and your hair keeps falling out. Biology tells us this.

      Daniel Merk wrote on May 23rd, 2011
    • I feel sorry for your bones….

      Primal Palate wrote on May 23rd, 2011
  34. Keep destroying the planet to satisfy your appetite. You’re right. The meat and dairy industries can just buy us a new earth when this one is tapped out. If your TWO pansy ass, tiny little canines and your lightning fast speed and razor-sharp claws (haha!!) Are enough of a reason to pretend to be omnivores, cool. But your cooked, seasoned, sauced-up meat is not the caveman diet you’re all so proud to be following. True carnivorous can hunt, chase, bite into and rip apart an animal. They devour every trace of meat in their bones, including their face, eyes, guts, etc. All RAW. I dare you to kill a chicken and then eat it’s flesh. You know what? Even try boiling it before you eat it to make it more tolerable. It tastes like shit. Be meat lovers. Go ahead. But claiming it as natural to the human race is a joke. Calling on evolution to make a point is showing a misunderstanding of the way evolution works.

    Sunny wrote on May 23rd, 2011
    • You can’t seriously claim that humans evolved being vegans?

      On the other hand I understand what you mean. If we keep promoting this way of eating within a short amount of time we’d be out of resources.
      We are already short on resources, that’s why there are feedlots and empty oceans.
      People need to stop having 3+ children. Population control is in order.

      Also, Mark Sisson doesn’t promote a high meat diet, in his book (which you probably haven’t read) he states that the bulk of the meals are supposed to be vegetables!

      Most of us here don’t buy feedlot meats and chicken from commercial stores fattened on soy. I agree, that type of chicken does taste like shit!

      Primal Palate wrote on May 23rd, 2011
    • And – forgot to meantion this one, we do have Vegetarians on board of the primal diet, too.

      Primal/Paleo just means cut out things we didn’t evolve on FOR SURE, which is grains and processed sugar.
      Can’t argue with that. You can be vegan and primal.

      Primal Palate wrote on May 23rd, 2011
    • We agree. The dairy and meat industry is indeed taxing the planet. But on this forum, we work with farmers, not big agri business. Also, this forum is all about veggies and animal protein. Lastly, don’t fool yourself into thinking that by giving up on animal husbandry the plant farmers are going to save the planet. Just about every species smaller than a cat suffers. There are plenty of books on the subject.

      Daniel Merk wrote on May 23rd, 2011
    • Ah – and there it is…

      If vegetarian eating is about health – why do you lot ALWAYS default back to the ecology argument!?

      You have NO understanding of evolution if you think that the fact we no longer eat meat raw is proof that we are not meant to eat it.

      We CAN eat meat raw, and if we couldn’t cook we would. But cooking makes food easier to digest and enables us to access nutrients in foods we could NOT otherwise eat.

      What is more an issue is you are so dogmatic about your view, you FAIL to recognise when you are making points against your own argument..

      NO OTHER ANIMAL cooks it’s food!!!

      Why don’t you eat all your food RAW!?

      Tell you why:

      1) Potatoes – inedible
      2) Wheat – inedible
      3) Corn – inedible
      4) Rice – inedible
      5) Legumes – inedible

      In fact ALL the above are either poisonous or at a minimum toxic enough to make you VERY sick if you don’t cook them!!!

      Most primates are omnivores. Humans do not require claws, as we can track and hunt and even use tools. Additionally, opposable thumbs mean all primates can hunt without claws.

      Our digestive tracks are FAR too small to be true herbivores (i.e. only eat green leafy matter and fruits).

      Humans CAN get by eating the above GRAINS, as despite our anatomy that is too different from animals that are are truly able to eat plants, these food sources give us energy quickly enough to be useful… but they ARE TOXIC raw!!!

      So it is impossible for a human to be a vegetarian, because for those of us that UNDERSTAND evolution:

      1) prior to eating grains (10,000 years ago) eating only vegetables/fruit would meant starvation

      2) And prior to 50,000 years ago we could not cook our food, so we couldn’t eat the grains and legumes and potatoes etc listed above that are toxic for humans when eaten raw.

      So why don’t YOU eat your food raw?

      You wouldn’t survive without MODERN farming giving you YEAR round fresh fruit.

      If you just ate vegetables, with NO grains you could NOT survive.

      And as to your environmental concerns – you are completely ignorant of the FACTS

      1) Corn and soy farming causes some of the WORST environmental degradation of land on this PLANET – PERIOD.

      2) CORN/Soy/Grain fed animals are definitely a problem for the health of our planet and our own health

      3) Cows, chickens, pigs, sheep etc raised on GRASS are environmentally GOOD. This is a fact. There were up to 60 million bison in North America roaming the plains.., the reason the plains of North America were so fertile was due to these animals.

      Where ever on the planet there are NOT grazing animals the land DEGRADES to arid land…

      Grazing animals provide part of a CHAIN of life.

      You pseudo greenies that use your eating habits to push a flawed agenda, do not TRULY understand ecology, you have a “religious” or philosophical belief, and you use emotion (like your rant above) to push your agenda and try and make people feel guilty…

      Well go actually learn about ecology and nature AND Evolution…

      You will find that you disgust for meat eating is so fundamentally FLAWED. The fact is – without meat eating animals and humans the planet would not have as much biodiversity as it does today.

      Of course I am wasting my time on you (but perhaps not some other person reading this)… as you would NEVER give up your belief system – no matter what the ACTUAL FACTS…

      Luke wrote on June 2nd, 2011
      • This is a quote from Mark; The lion’s genetic makeup was shaped by meat-eating. Its teeth and claws are made for killing, its digestive tract is meant to process protein and fat. You might even say the lion’s genes expect the ancestral lion diet of raw meat and function best on such a diet. Conversely, a diet that diverges dramatically from the ancestral lion diet will probably be harmful…”
        Humans do not have this make up, we do not have the digestive system to eat meat, we do not have the teeth. Look at a carnivore’s teeth, nothing is similar. I do believe that we should not eat any type of grain, it wasn’t around as we evolved. I think eggs, nuts, seeds, fruits, veggies, fish, anything that was easily available to early humans is what we should eat. Agriculture is destroying our plant and health. If we did not eat meat, there would be no negligible pollution. 90% of the worlds agriculture is for the animals people eat, not for humans. Only 10% is realized back in the form of a food that is not digestible, unless cooked, and unhealthy for humans. The beef industry pollutes, uses more energy, more fuel and more fresh water than all other reasons on earth. We already eat too much meat . Why do you need all this fertile land if we do not need the agriculture? Just to pollute the planet? If you cook anything over 104, it looses any benefit for nutrition. The human body actually functions best on fruit, it digests and gives you energy in 20 to 30 minutes, veggies take 4 to 6 hours and meat never really digests or gives you energy. Your argument about athlete’s don’t matter because very few are, what about those that are? Try eating anything but fruit before a day of high exertion and see what happens. Digestion is the #1 user of energy in your body, about 75%. You only have 25% left to perform if you ate meat, even the day before. I believe a lot about this PB diet, everything but the meat! There is far too much evidence against raising, grazing, feeding, torturing and murdering animals for man’s food, health, pollution, ethical and moral issues to think that is acceptable. almost all the meat available is garbage because the animal was fed grains that it is not supposed to eat. And given drugs and steroids to help it survive and make it fat. I am 66 years old and still perform better than most teenagers at an extreme sport that requires more physical conditioning that any other for over 45 years. I have not ate any meat in 30 years and stopped grains 5 years ago, mainly the PB diet without the meat. I am in perfect health and have never taken a single drug of any kind. I am totally NOT religious either, morality does not come from a god. Those are the actual facts.

        B wrote on December 27th, 2011

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