This is an absolutely wonderful article that everyone should read:
Andrew Kim Blog: Diet Dogma Rears Ugly Head Again: Become a Fat Burner, Eat Your Own Crap, and Live Longer
My favorite quotation is where he references Mark Sisson's article itself:
There are so many other good ones.[...]this desire to push back Father Time has spawned and perpetuated some pretty awful ideas which have no basis in any reasonable level of evidence.
One such idea, actually a few related ideas that I’ll roll into one idea here, is to limit the amount of glucose our cells burn over the course of a lifetime, so as to turn on a primitive stress response mechanism called autophagy, a process whereby cells degrade and recycle their dysfunctional components in the face of nutrient depleted conditions. Unfortunately, this necessarily entails burning proportionately more fatty acids for fuel (or what’s called being “fat adapted” in horribly egregious articles filled with wishful thinking like this one) and turning down thyroid functioning, or the rate at which we live, adaptations that are directly at odds with reaching our full potential as human beings.
Maintaining tissue responsiveness to hormones is, I believe, a key factor in slowing down the aging process. Consider Progeria, a syndrome famous for producing an apparent accelerated aging in children. Progeria is characterized by a massive reduction in the responsiveness of cells to all hormones – a defect thought to drive the degenerative conditions that appear in children with the condition.
A cell’s responsiveness to hormones is most sensitive when the stress hormones, free amino acids, and free fatty acids in the blood are low. For example, a deficiency of growth hormone, a stress hormone secreted by the pituitary gland, leads to an inflated sensitivity to the hormone insulin in adulthood.Another feature of Progeria, which animal models of Progeria and the like have unexpectedly found, is an increase in autophagy – an effect touted as highly desirable among Paleo, low-carbohydrate, and caloric restriction advocates. The molecular mechanisms are not well understood, but it does help to explain, to me at least, why chronic dieters look so haggard and the opposite of healthy, vibrant, and attractive; sometimes, as if death has warmed over. Simply put, autophagy is an adaptive response to metabolic stress that when chronically activated drives premature aging by inducing catabolic processes that outpace the renewal ability of cells. An increased oxidization of fat in preference to glucose is a key feature underlying this downward metabolic shift, as well as an impairment of mitochondrial respiration and a decline in ATP levels.This is wonderful stuff.Whether we like it or not, autophagy will occur in all of our cells. It is a primitive form of protection that allows cells to dispose of misfolded proteins, misassembled protein complexes, damaged mitochondria, and so forth. There is absolutely no need or reason to force it to occur artificially with special diets – especially so if you’re already healthy. Undue misery is sure to follow from this self-imposed deprivation. Interestingly, all the conditions that bring about autophagy are at odds with the conditions that maximize our potential as organisms, and this entails the thyroid hormone and oxidation of glucose for fuel. I think it’s time for us to toss the idea of diet-induced autophagy into the pile with the other worthless dogmas that have done little more than leave the landscape of diet and nutrition understanding in disarray.
Mark Sisson's core concept of The Primal Blueprint is a sound one - eat real, fresh, nutritious whole foods, avoid processed, low-nutrient/high anti-nutrient foods. But then he has to go and muddy the waters with groundless bullshit to create a unique product that he can trademark as his own and sell. On one hand he advocates whole foods, but on the other he advocates added fats. He has this ridiculous and groundless "Carbohydrate Curve" that completely undermines the consumption of real food - you can eat all the meat and eggs you want, but you have to count your fruits. It's a cardinal sin to add a 16 calorie packet of white sugar to your coffee, but it's okay to emulsify half a stick of butter in it.
I've said it before and I'll say it again: there is no such thing as being "fat adapted." We burn fat and glucose for fuel simultaneously at all times. If at any time you are not burning fat and glucose, you are dead. The goal of this diet shouldn't be to avoid fat or carbohydrate or any specific macronutrient. It should be to try and maximize the nutrition we get for each calorie of food we eat. Displacing real food for oils does the same thing as ordering pancakes instead of eggs - you remove nutritious foods for low-nutrient garbage while taking in the same amount of calories. Our goal here should be to eat high quality whole foods that maximize our health. That is how you keep the metabolic rate the highest, and what we want here is to have a high resting metabolic rate. We want the energy of youth - flush skin, high body temperatures, we want to be able to breathe out of our noses alone comfortably without being "mouth breathers," we want a heart rate of around 70, etc. We don't want to be cold and clammy with pale skin and a low heart rate, requiring constant mouth-breathing because our blood oxygen levels are so low from inefficient mitochondria. These are signs of aging and DEATH, not youth and LIFE. This is what carbohydrate restriction and autophagy gets us. Why we would want to emulate rapid aging is beyond me.