One thing that the recent Taubes meltdown at AHS has done is elicit the reappearance of the LC Kindergarten Cop in comments sections far and wide. Yes, I'm talking about the hopelessly mired in parroting LC dogma Fred Hahn. He's pulling back out the "teaspoon of sugar" schtick to proclaim that carb consumption is evil. It just so happens I had addressed this in a recent post: Let's play Concentration!
In that post I did the calculations on the circulating levels of the form of fat we burn at any given time. For a normal person, this comes out to around 0.5g fat. Using more elevated levels we're still talking at most about 1g fat. Using even a low end density for oils and butter, 0.8 g/ml, we're talking 1.25 ml. What's that in teaspoons? One-quarter of a teaspoon. (One eighth teaspoon for normal individuals, and knocked down to around one thirty-second of a teaspoon after a meal!)
Let's presume a 2000 cal diet with 65% carb or 65% fat. That's 325g carb or 65 teaspoons of sugar. For fat that's 144g fat or 36 teaspoons fat. So 65X circulating levels of glucose or 144X circulating levels of fatty acids. So what is the point of this teaspoon stuff?
I would hope that looking at those numbers makes the point that the instantaneous, absolute circulating levels of substrates vs. dietary intakes are meaningless. Indeed to my view, that a normal person's blood glucose levels only go up about 1/2 teaspoon after even a carby meal is testament to the rapidity of clearance of glucose from circulation. And, as was commented in my last post, if circulating NEFA are so low how do we ever lose weight? The answer is that the absolute concentration is meaningless other than to know what is normal for physiological function. The glucose and fatty acids are circulating, being taken up by cells and being released/taken up by liver, perhaps kidney, and adipose tissue (glucose uptake only). It's turnover/flux that is important.
The absolute number that really matters are the calories associated with those substrates. Burn 2000 cals/day it doesn't matter if you consume it as all fat or all carb, it gets used and your circulating levels of glucose and fatty acids remain normal.
So what's my purpose in repeating this? Perhaps so there's a shorter version of the Let's Play post folks can link to whenever someone drags out that tired old teaspoon of sugar nonsense to mandate VLC diets for all.