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.