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Carbs and Metabolic function

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  • Carbs and Metabolic function

    First I will start off by stating that I do not believe Primal is the only way to be lean and healthy, but it sure seems like the best and for me it is the tastiest. The one thing I add to PB is some pwo carbs after weight lifting. But I was curious after going over Ori Hofmekler's Warrior Diet.

    __________________________________________________ _______________________

    Diet Fallacy #5: CARBS Are Your Enemy

    Carbs are currently regarded as the culprit for the on going epidemic of overweight, obesity and their related disease. It has been commonly assumed that carbs are not essential nutrients and therefore could be severely restricted or even spared. Low carb diet advocates argue that insulin is a fat gain promoting hormone and therefore should be tightly controlled by chronically restricting carbs. Due to the current popularity of low carb diets, it seems as if carbs are the enemy. But are they? As you'll soon see, nothing could be so far from the truth.

    Let's examine the assumption that carbs are not essential nutrients. This assumption literally fails to recognize the two most critical biological functions of carbs (besides being a fuel):

    The activation of the pentose phosphate pathway (PPP)

    The finalization of growth hormone (GH) and insulin like growth factor (IGF1) actions, as well as the enhancement of androgens actions.

    Let's cover briefly the importance of the above functions. The pentose phosphate pathway (PPP) is a critical process that is responsible for the synthesis of DNA, RNA and all energy molecules including ATP and NADPH, needed for all metabolic functions in particular, recuperation (healing of tissues), immunity and growth. In addition, the PPP is a precursor for another metabolic pathway-(i.e. the uronic acid pathway) responsible for steroid hormones transport, production of proteoglycans (essential for connective tissue and cellular signaling), synthesis of spingolipids (lipids that are necessary for neural protection) and over all detoxification. The pentose phosphate pathway, which occurs mostly in the liver, is derived from glucose (i.e. carb metabolism). Now, here is the problem...

    In times of a desperate need for energy, such as during prolonged starvation or due to chronic severe restriction of carbs, the PPP would shut down its main function and instead switch into sheer energy production. It is likely that energy demand is a top priority for the body and therefore, in times of a desperate need for energy, the body would suppress certain important metabolic function (such as the PPP) to accelerate immediate energy production. Note that 30% of glucose oxidation in the liver can occur via the PPP.

    One may argue that glucose can be synthesized from fat or protein. Yes, but not enough! Since the synthesis of glucose from fat or protein (gluconeogenesis) is actually a very limited metabolic process that occurs mostly in the liver, any severe restriction of carbs, in particular for active individuals, may adversely suppress the PPP critical functions; due to insufficient glucose supply during an increased energy demand.

    The PPP actions also decreases with age, a fact that may contribute to the decline in steroid hormone production and the typical muscle waste, that is associated with aging.

    To sum up this part, dietary carbs are necessary for the full activation of the PPP and its critical functions. Severe chronic carb restriction (below 70g-100g for an active individual) may lead to an adverse suppression of PPP, with an overall decline in sex hormones, compromised immunity, impaired growth and accelerated aging.

    As noted, besides playing a vital role in the activation of the PPP actions, dietary carbs also help finalize the actions of the most anabolic agents including growth hormone, IGF1 and the sex steroid hormones.

    Studies at Stanford University in CA and Helsinki University in Finland revealed that insulin is a potent promoter of IGF1 and the sex hormones action. Researcher found that insulin help finalize the anabolic actions of GH, IGHF1 and androgens by down regulating certain proteins that suppress both IGF1 and androgens action, in particular in the muscle tissue, (i.e. IGHFBP-1 and SHBP, respectively). A recent study at the University of Texas, indeed proved that post exercise carb supplementation together with essential amino acids profoundly stimulates net muscle protein synthesis.

    Interestingly, simple carbs had a more profound effect on enhancing anabolic actions after exercise than complex carbs. Nonetheless, as a general rule, our body is better adapted to utilize complex carbs than simple carbs. Again, it is when you eat that makes what you eat matter.

    In conclusion, dietary carbs biological functions go far beyond just sheer energy production. Chronic carb restrictions may lead in the long run to total metabolic decline with severe consequences on survival (i.e. capacity to regenerate tissues and procreate). Carbs are not the enemy, ignorance is.

    __________________________________________________ ________________________

    The thing with his argument are primitive people who live on nothing but animal at and protein year-round. What do you guys think? I mean, his conclusion is completely far fetched.

  • #2

    Carbs are not required for health. The Masai and Inuit are testament to that.

    Carbing up is a pointless waste of effort.

    The "Seven Deadly Sins"

    Grains (wheat/rice/oats etc) . . . . . Dairy (milk/yogurt/butter/cheese etc) . . . . . Nightshades (peppers/tomato/eggplant etc)
    Tubers (potato/arrowroot etc) . . . Modernly palatable (cashews/olives etc) . . . Refined foods (salt/sugars etc )
    Legumes (soy/beans/peas etc)


    • #3

      Wow. Mr. Hofmekler needs to learn how to write at a middle school level before he gets into graduate level biology. If your name is not George Bernard Shaw, you don't just get to ignore apostrophes.

      Glucose levels are homeostatic, first of all. Your body needs it. Your liver will make it. And it will go to fairly great lengths to make sure you have enough to keep your brain and other glucose-exclusive tissues going. You can produce 150-200g/day via gluconeogenesis, and your requirement may not be that high if you're in ketosis and partially fueling your brain that way. Eating 200g per day of carbs would not be considered "low carb".

      Second of all, this article is not a review of the literature, but a persuasive piece intended to give the impression of factual narrative. He does not provide citations (even on the original page). He uses the word 'may' (as in has never been observed, but is hypothesized) a lot.

      He tries to say that the pentose phosphate pathway "finalizes" growth hormone, IGF1, sex hormones, etc. but then goes on to say that insulin is actually a promoter for the action of those hormones. Guess what, you still have insulin if you have a functioning pancreas. If you have fasted for 24 hours, you are still producing insulin, because your liver is making glucose. Consuming protein also releases insulin.

      Furthermore, let's just take as an example IGF1. IGF1 is a tyrosine kinase. Its job is to phosphorylate a tyrosine residue on the IGF1 Receptor. The phosphate group in that reaction comes from ATP. ATP is produced separately from the PPP. Glycolysis takes care of it just fine. In fact, beta-oxidation of fats by the cell produces Acetyl-CoA, which can enter the citric acid cycle and be metabolized into ATP. None of this requires dietary carbs.

      Does he seriously expect us to believe that, given the fact that numerous carnivorous animals exist that do not consume dietary carbohydrates, but are nonetheless muscular, deadly, and extremely virile, we humans somehow evolved to depend on dietary sugar in order to process IGF1, a hormone which has been around since well before there were any mammals, and several other critical signals?


      • #4

        I am an empiricist. While theories and certainties are sometimes interesting, the bottom line I care about is what works.

        We know that the low fat, no saturated fats, lotsa carbs diet has been a dismal failure. All those "experts" and our own government and busy body organizations like the Center for Science in the Public Interest have led us down a path of death.

        Somehow, people who have been ignoring this best advice are winding up the healthiest. As Nick says, this guy is bad science, bad writer.


        • #5

          Actually OnTheBayou, he is not a bad writer, without Ori I would NEVER have found Mark and the Primal community. He was also my first experience with Intermittent Fasting.

          If you read over the link you'll see that his diet is pretty solid. Not to mention that the guy is absolutely ripped at 50!


          • #6

            Just because he proved useful to you and pointed you to some key elements does not make him a good writer. Bad writing is bad writing.

            And lots of people are *ripped* who follow a more conventional diet. What's your point? You can bulldog your way to an impressive physique if you're brutally disciplined. That doesn't mean it's the best way to go and it is certainly not necessarily something that will work for everyone.


            • #7

              I don't have a detailed knowledge of the various metabolic pathways and I have been repeatedly told by various hardcore personal trainers that simple PWO carbs "won't make you fat, hence are very efficient for muscle and liver glycogen replenishment".

              I've been following a 4x week, intensive weight training programme for a number of years, am currently around 13%body fat and have been following a lowish carb, high fat/protein diet for around 18 months. Carb intake is around 120 gms/training days, 80/90 gms on rest days, all from vegs/nuts.

              In the last 2 weeks I have removed simple carbs from my PWO meal. I've noticed a reduction in performance, particularly on squats and to a lesser extent on some other exercises.

              I've replaced the PWO protein + 50g simple carbs with a PWO protein only shake immediately afterwards and a solid meal of protein, fat and veg carbs(approx 30g carb content) within 1.5 hrs of training.

              I'm also experiencing what I'd describe as a period of exhaustion around 1.5 - 2 hrs after training.

              I intend to persevere with this regime for at least 4 weeks to determine whether the reduction in performance (around 5% drop in working weight lifted)

              and hightened PWO tiredness are just symptoms of a period of adjustment or proof that simple carbs immediately PWO support faster recovery and more efficient liver/muscle glycogen replenishment.

              I'd be keen to hear about the experiences of anybody that has removed PWO carbs, any impact on training performance, strength, period of adaption.


              • #8

                I would give yourself a month to adjust to your new regimen of lower carbs. I work out at a Crossfit gym and we have guys who eat <150 grams of carbs a day and can outlift and outperform a lot of the elite personal trainers telling you to eat simple carbs post-workout. I've seen some of these guys do workouts with 50 reps of deadlifts at 2x bodyweight combined w/ running, pull-ups, double unders(jump rope) all in the same workout. Give it some time-you don't have to sacrifice health for performance.


                • #9

                  @Conan, thanks for the input. yep definitely going to give it a least 1 month.

                  "50 reps of deadlifts at 2x bodyweight combined w/ running, pull-ups, double unders(jump rope) all in the same workout"

                  That's incredible - I know a couple of very strong trainers but they'd never manage that combination of strength and endurance. I think I need to take a look at crossfit, may be replace one of my current 4 workouts with a crossfit session since that level of health would be a truly meaningful and worthwhile goal.


                  • #10

                    Wow, Nick. I'm impressed with your posts. Seems you know a lot about metabolism and biology. What's your background?


                    • #11


                      I've been lifting weights for 15 years and no routine I've tried has generated the gains I've seen from Crossfit. It also happened to change my body faster than any other fitness regimen I've tried (I credit my Paleo/primal diet with a lot of that as well). Let me warn you about a couple of things though:

                      1. Due to the intensity and very heavy weights you are working with, it is pretty easy to injure yourself. My girlfriend and I have both suffered minor injuries on multiple occassions. So start slow and ease your way into it. If you are competitive, you are probably going to try to keep up with the big boys and end up w/ an injury. You will get beat by girls when you are first starting so check your ego at the door.

                      2. Some of the gyms suggest 5-6 crossfit sessions / week and that crossfit is all the working out you should do. Due to the intensity involved I think this is too much volume and leads to #1 and also slows muscle building (you will find that many Crossfitters, while insanely strong, do not have huge muscles). Peronsally, I have seen major strength gains w/ Crossfit 2-3 times/week and heavy lifting sessions 2-3 times / week with an occassional sprint workout.

                      3. If you are an endurance athlete, do Crossfit endurance. The normal crossfit workouts don't really build endurance for activities that last more than 30 minutes.


                      • #12

                        Never heard of him!

                        On the other hand I HAVE heard of Eric C Westman of Duke, currently a leading 21st century dietary and metabolic researcher


                        I can only speak personally but my body agrees with him. Oh wait, so do several hundred if not several thousand other bodies


                        • #13

                          the warrior diet is a pretty good plan. For those unfamiliar with it, Ori suggest undereating during the day and eating a large meal at night.

                          The main tip that I personally learned from the book was that it is ok to be hungry during the day and to skip breakfast when not hungry. I had been locked into a pattern of eating three meals per day and for a while was going from meal to meal eating without even being hungry.

                          Otherwise, during the day, when hungry eat preferably in this order vegetables, fruit or light protein like eggs, yougurt or kefir. So as to lessen the impact on the body's detoxification that started the previous night.

                          At night, for dinner, he suggests eating from all of the food groups however, he suggests a certain order of eating, if at all fruit first, then vegetables, then meat and finally carbs last. He also is against processed foods, sugar etc.


                          • #14

                            I don't think Grok gave a damn what he ate when.

                            Too much trouble and discipline considering I am doing great with PB. Sooooooo EZ.


                            • #15

                              I like the Blueprint better myself. Although, there was a tremendous freedom in allowing myself to not eat during the day and then eating my main meal at night with my family. That experience is not contradicted by the blueprint at all and Mark is an advocate of IF.

                              Ori uses his own metaphor in his book about carrying the kill/meat home and cooking it around a fire and eating together with the tribe, which in his book takes place at night.

                              To my way of thinking, the diets have more in common than less in common.