Sep 14, 2026 · 57 min · 12 segments
What if the sugar affecting your metabolism isn't just the sugar you eat? In this episode of the Biohackher Podcast, I sit down with metabolic health researcher and educator Chris Mearns to explore…
Chris MearnsGuest
Azra AlagicHost
Now, one of the most surprising parts of your work, I think, is that we don't necessarily have to eat fructose for our bodies to make it.

So the body makes its own fructose through a pathway called the polyol pathway.

And effectively what happens there is it uses a spike in glucose levels to convert glucose into sorbitol and then sorbitol into fructose.

And so it's starting to appear that the issues that we blame on glucose, like we wear glucose monitors and we, we watch our glucose levels, that high glucose in itself is not seemingly problematic, and that is, that is starting to be recognized when you inhibit fructose metabolism because the, um, metabolic endpoints that we would otherwise attribute to high glucose levels suddenly drop off quite significantly.

I, I, I think of it this way, where it's like we don't often blame our car for underperforming because we have too much fuel in the tank.

And so by that argument, this is a kind of a funny way to think of it, but the problem with the fuel could be when the fuel goes bad because you simply have too much of it.

If it, if it's converting into fructose and then the fructose is sell- sending a, a conserving dial-down signal to your engines in your cells- And suddenly that's where you're going to start to see the problem come out.

So then we have to start asking, how does the body make fructose? Well, it does it with high glucose levels, and so then high glycemic carbs become highly relevant to the story.

It also does so through dehydration because osmolality allows the body to manufacture fructose as well.

It still depends on carbs, it still depends on glucose, but it, it kind of piggybacks onto that.

So then that means that dehydration, high salt levels, or alcohol all contribute as well because they all influence the osmolality of our blood.

And so suddenly it starts to look like, hey, we talk about this stuff all the time.

And we're all probably well aware that when we start gaining weight, we start getting sleep apnea.

And suddenly it's like, okay, we've got carbs, we've got salty foods, we've got dehydration, we've got-- Even umami foods play a role in this because...

Now, one of the most surprising parts of your work, I think, is that we don't necessarily have to eat fructose for our bodies to make it.

So the body makes its own fructose through a pathway called the polyol pathway.

And effectively what happens there is it uses a spike in glucose levels to convert glucose into sorbitol and then sorbitol into fructose.

And so it's starting to appear that the issues that we blame on glucose, like we wear glucose monitors and we, we watch our glucose levels, that high glucose in itself is not seemingly problematic, and that is, that is starting to be recognized when you inhibit fructose metabolism because the, um, metabolic endpoints that we would otherwise attribute to high glucose levels suddenly drop off quite significantly.

I, I, I think of it this way, where it's like we don't often blame our car for underperforming because we have too much fuel in the tank.

And so by that argument, this is a kind of a funny way to think of it, but the problem with the fuel could be when the fuel goes bad because you simply have too much of it.

If it, if it's converting into fructose and then the fructose is sell- sending a, a conserving dial-down signal to your engines in your cells- And suddenly that's where you're going to start to see the problem come out.

So then we have to start asking, how does the body make fructose? Well, it does it with high glucose levels, and so then high glycemic carbs become highly relevant to the story.

It also does so through dehydration because osmolality allows the body to manufacture fructose as well.

It still depends on carbs, it still depends on glucose, but it, it kind of piggybacks onto that.

So then that means that dehydration, high salt levels, or alcohol all contribute as well because they all influence the osmolality of our blood.

And so suddenly it starts to look like, hey, we talk about this stuff all the time.

And we're all probably well aware that when we start gaining weight, we start getting sleep apnea.

And suddenly it's like, okay, we've got carbs, we've got salty foods, we've got dehydration, we've got-- Even umami foods play a role in this because...
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