Random Thought 💭

[Robert_Johnson]

While reading The Obesity Code, I was struck by this thought.

While it’s true we can use glucose as fuel. It doesn’t mean it’s “preferred”. I keep hearing glucose is preferred over ketones. Which is why fall out of Ketosis when eating carbs.

But I think it’s being misstated. Instead of being a preferred fuel source, maybe instead it just takes priority over ketones.

Sugar can be burned as fuel. But having it just sitting around, accumulating, is a very bad thing. So perhaps our bodies just make it a priority to hurry up and get rid of it.

This makes sense in context of a hunter gatherer eating meats during the spring and summer months, followed by eating fruits once they become available in the fall. Eating those fruits fattens up the hunter gatherers for the winter when food is going to be scarce. I know, that’s been covered. I’ve heard that before too. But I still keep hearing how glucose is a preferred fuel over ketones. I would like to think of Ketones as being the preferred fuel source, but our bodies need to switch over when Blood glucose gets high, and release a bunch of insulin to get rid of that harmful stuff.

Nature does everything the easy way. So I guess using it as a fuel is better than getting the kidneys to flush it out.

Thoughts? Did I make sense?

[keehan]

Gasoline, if you put a match to it, will burn fast, almost explosively. Diesel is almost impossible to light in the same scenario, but once it lights, it burns steadily and for a much longer period. However, there is more energy (about 15% more) in a litre of diesel than gasoline.

…this is how I think of the glucose - ketone comparison.

[Ajax]

Agree, the concept of ‘preferred’ is not fully accurate - its just a matter of what’s readily at hand. I don’t have the reference directly - but I do recall Dr Jason Fung describing it like this (not a direct quote - and broadly paraphrased): we store food (fuel) in the fridge (gluscose) and the freezer (fat). When we are need of fuel - we go to the fridge - its quick, easy and readily accessible. Our fat fuel is like food in the freezer. Its there and we can use it for fuel/energy/dinner but it takes some more effort to access.

[Stef]

Alcohol is burned before sugar. Does that mean it’s the ultimate “preferred fuel” ?
Drink up me hearties, yo ho.
Why is the rum always gone

[Melanie]

Nora Gedgaudas sums up metabolism as being like a fire with glucose being burnt quickly like kindling, fat being like the big logs that burn slowly and alcohol is like throwing gasoline onto the fire

[MySugarFreeJourney]

I usually say that fuel is burned in order of toxicity. So alcohol is the most toxic fuel so that gets burned first, then sugar is less toxic than alcohol but more toxic than fat, then finally fat, the “safe” fuel. Remove the first 2 fuels and your body runs on fat.

[Shortstuff]

@Stef I was about to say this exact thing.

[PaulL]

Sugar can be burned as fuel. But having it just sitting around, accumulating, is a very bad thing. So perhaps our bodies just make it a priority to hurry up and get rid of it.

I usually say that fuel is burned in order of toxicity. So alcohol is the most toxic fuel so that gets burned first, then sugar is less toxic than alcohol but more toxic than fat, then finally fat, the “safe” fuel. Remove the first 2 fuels and your body runs on fat.

Robert, I think this is the best way to look at it. Dr. Phinney describes the presence of a high level of glucose as a “metabolic emergency” that needs to be deal with right away. And ethanol is definitely more immediately toxic than even the fructose moiety of sucrose.

[Robert_Johnson]

Yep @PaulL, you’re kinda making my point. Priority, not preferred. I wasn’t even considering alcohol as a fuel source. Is it? Does it get converted into fuel useable by the mitochondria in our cells? Or does the liver just break it down to get flushed out, like other toxins. For that matter, are there other chemicals that we could possibly be using for fuel, that the liver can convert? Is MCT and example of this?

As I stated, just thinking these things. I often get side tracked by things like this and if I don’t air them out, I dream about them. Yes, some pretty boring dreams when that happens I tell ya!

[PaulL]

Alcohol and fructose both stimulate de novo lipogenesis in the liver, so I guess they could be called fuel sources without too much of a stretch. Some of the molecules also get converted into acetyl COA, which, if memory serves, is a precursor to ATP. If you feel like wading through Dr. Lustig’s lecture, “Sugar: The Bitter Truth,” he goes into the metabolic pathway fructose and ethanol take in the liver in quite a bit of detail. Several versions of that lecture are available on YouTube.