There's no dietary need for saturated fat ...

Random Bump!

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Original Publish Date:  6/15/12

There's no dietary need for saturated fat ...

... or monounsaturated fats, MUFA, for that matter.  Therefore low fat diets, where most of the fat is essential PUFA, are optimal.  The body can make all the SF and MUFA we need from carbohydrates.  Furthermore, relying on this metabolic pathway as a source of body fat is metabolically advantageous for weight management as making fat from carbohydrate is an energy intensive process.  

Sounds a little silly, right?  I think so.  But so, too, is the ridiculous mantra from low carbers citing the fact (true) that there's no dietary necessity for carbohydrate.  You know the drill, we can make all the glucose we need by gluconeogenesis (just saying that makes me feel smarter) therefore LC diets are optimal.  There is a metabolic advantage built into LC diets because gluconeogenesis requires energy to convert protein to glucose.

And then there's the teaspoon crowd.  You know them, the ones touting the whole "you only have a teaspoon of glucose in circulation at any time" meme, that makes you think eating a normal carb load will explode your brain.  That's based on this calculation:

I repeated that calculation for NEFA which is a little more complicated as fatty acids come in different masses/sizes so converted molar concentrations are more approximate.  Still,  using typical fasting levels of 400 µmol/L and 250 g/mol as the molecular weight of the fatty acid (palmitic acid for example if 256):

Do they make 1/10th teaspoons?  OK, those calculations are a repeat, but when you keep hearing the whole teaspoon thing, it bears repeating the calculation for fatty acids as well.  It is largely irrelevant, but just as postprandial glucose levels can be spiked by dietary glucose w/o appropriate metabolic response and clearance, so too postprandial NEFA levels can spike w/o the appropriate metabolic response to trap and prevent inappropriate release from adipose.

But let's go back to the "dietary need" argument shall we?  There is no dietary need for carbohydrate, but the body goes to great lengths to conserve glucose when availability is low, and to protect against too low a level.  Thus, in all humans, gluconeogenesis occurs at significant rates for varying periods during every day.  This is higher in low carbers with depleted glycogen stores to provide some of the glucose the liver must produce.  Indeed it appears that gluconeogenesis is an "always on" process that is largely regulated via suppression.  Apparently our need for dietary fatty acids is nowhere near as necessary.  De novo lipogenesis, DNL, is a minor path in humans and difficult to stimulate to anywhere near significance absent substantial and chronic overfeeding.  Furthermore, unlike glucose, the absence of fatty acids in the diet does not stimulate their synthesis.   We go to great lengths to expend energy to make sure glucose is available, we go through no such lengths to make sure fatty acids are ...

Now I'm not saying this really means anything.  Rather my point is that all of the glucophobic mantras intended to scare you into ketotic shock are rather meaningless as well.  

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