IF question

Crisseyda

I've been doing keto for years, but new to learning about intermittent fasting.

A lot of the research on the two seem to be separate, but from what I can understand the underlying mechanism of benefit seems to be the same: a switch to fat metabolism, which means cleaner energy, less oxidative stress, increase in mitochondria, ketone production and other beneficial enzyme activation.

So, my husband is not keto, but he's decided to keep his eating within an 8 hr window. Fat metabolism benefits occur even with this eating style (from what I assume is the shift into mild ketosis toward the end of the fast). Based on my thinking, I told my husband that if he really wants to eat something (he hasn't done it yet) during the fast phase, that a snack with 0 carbs shouldn't really affect what's happening. Is this true? Or would even protein give an insulin response enough to have an effect?

nicsflyingcircus

From my understanding, pretty much anything that isn't basically all fat will interrupt the processes that make fasting beneficial.

wabmester

I'm sure you know this, but ketosis and fat metabolism are two different things (ketosis is partial oxidation of fat).

Anyway, just about any meal will affect insulin levels. But ZC is pretty close to fasting.

Crisseyda

Thank you, this is what I was looking for! What do you think are the biggest differences between fasting and just fasting carbihydrates? And what do you mean by partial fat oxidation?

wabmester

Depends on your goals for IF. Valter Longo thinks suppressing IGF-1 is important, for example, if your goal is to reduce cancer risk. Protein impacts IGF-1. Fat maybe less so.

For info on partial oxidation of fats, here's the Wikipedia entry on ketogenesis:
https://en.wikipedia.org/wiki/Ketogenesis

Fatty acids are enzymatically broken down in β-oxidation to form acetyl-CoA. Under normal conditions, acetyl-CoA is further oxidized by the citric acid cycle (TCA/Krebs cycle) and then by the mitochondrial electron transport chain to release energy. However, if the amounts of acetyl-CoA generated in fatty-acid β-oxidation challenge the processing capacity of the TCA cycle; i.e. if activity in TCA cycle is low due to low amounts of intermediates such as oxaloacetate, acetyl-CoA is then used instead in biosynthesis of ketone bodies...

So the fat's not fully burned/oxidized in the process of ketone production.

A really good discussion of the (lack of) impact of ketones in weight loss comes from Peter Attia:
http://eatingacademy.com/weight-loss/how-to-make-a-fat-cell-less-not-thin-the-lessons-of-fat-flux

Does being in nutritional ketosis ensure negative fat flux (i.e., fat loss, or L > DNL + RE)?

Being in ketosis tells us nothing about this equation!

Crisseyda

wabmester wrote: »

Depends on your goals for IF. Valter Longo thinks suppressing IGF-1 is important, for example, if your goal is to reduce cancer risk. Protein impacts IGF-1. Fat maybe less so.

For info on partial oxidation of fats, here's the Wikipedia entry on ketogenesis:
https://en.wikipedia.org/wiki/Ketogenesis

Fatty acids are enzymatically broken down in β-oxidation to form acetyl-CoA. Under normal conditions, acetyl-CoA is further oxidized by the citric acid cycle (TCA/Krebs cycle) and then by the mitochondrial electron transport chain to release energy. However, if the amounts of acetyl-CoA generated in fatty-acid β-oxidation challenge the processing capacity of the TCA cycle; i.e. if activity in TCA cycle is low due to low amounts of intermediates such as oxaloacetate, acetyl-CoA is then used instead in biosynthesis of ketone bodies...

So the fat's not fully burned/oxidized in the process of ketone production.

A really good discussion of the (lack of) impact of ketones in weight loss comes from Peter Attia:
http://eatingacademy.com/weight-loss/how-to-make-a-fat-cell-less-not-thin-the-lessons-of-fat-flux

Does being in nutritional ketosis ensure negative fat flux (i.e., fat loss, or L > DNL + RE)?

Being in ketosis tells us nothing about this equation!

So, yes, I undrstand what you meant by partial oxidation. When I referred to a switch to fat metabolism, I mean enough fat metabolism to overwhelm the Krebs Cycle and divert Acetyl-CoA to the ketogenic pathway. While it is technically partial, I'm just comparing to the alernative of burning primarily glucose.

And yes, I agree ketosis does not equate weight loss because you could be burning fat from diet or fat from body stores.

I will check out Valter Longo about IGF-1. It's an interesting question, and as of yet, I can't find a good answer. They both seem very similar (almost exactly the same even) and beneficial, just wondering what the big differences are... and can my poor hubs still get away with a midnight snack during our mmo raids?

Crisseyda

So I found a video with Dr. Jason Fung, and with his severely insulin resistant patients on LCHF, the diet will not be enough to heal them because the proteins and fats are still instigating insulin. He has them fast sometimes for a week or two at a time! I guess with that in mind, it might best to eat nothing for the 16 hrs to get the full benefit.

kirkor

16 hours is when liver glycogen is fairly depleted and from what I understand that's when certain benefits start to kick in.