Glycogen, Fat burning, & Keto

jeniwilmot

So I keep googling and cannot find a clear answer really.

1. Is it better to burn fat than glycogen for weight loss? The only response I seem to get is, it doesn't matter -- what matters is burning calories.

2. I don't understand why it doesn't matter. And if it does at all matter, wouldn't calories from stored fat be more advantageous than glycogen toward the goal of weight loss?

3. For that matter, if folks keep replenishing their glycogen stores, won't they lose weight more slowly?

4. Lastly, if I keep switching back and forth between ketosis and glycogenesis, what effect does that have on my weight loss (hypothetically)?

Can any smartie pants break this down for me? Thanks!!

KetoCutie

You're already smarter than me just for asking this question! I have no idea - but I'm looking forward to the responses.

jeniwilmot

ah here's a good site: well.blogs.nytimes.com/2009/11/04/phys-ed-why-doesnt-exercise-lead-to-weight-loss/

kirkor

1. Neither is better for weight loss. Whether you're burning ketones or glucose, you still need a caloric deficit for a loss. Burning ketones instead of glucose can make a deficit easier to maintain for some due to less perceived hunger.

2. Using stored fat to produce ketones for energy instead of using glucose is what happens when dietary carbohydrate is restricted.

3. The rate of loss depends on the calorie equation. For many people, replenishing glycogen stores on a regular basis makes running a deficit harder because the foods higher in carbohydrate lead them to want to eat more.

4. Glucogenesis will occur if carbs are too low and protein is too high, which is why even on keto protein should be kept to a moderate level. In terms of weight loss, the 'switching back and forth' shouldn't affect your actual metabolic processes, but mentally it may be difficult if you are never getting to full fat adapted mode ... this is why cheat days and CKDs don't work for everyone.

DAM5412

You should read Volek and Phinney's "The art and science of low carbohydrate living" and " the art and science of low carbohydrate performance". Both fairly technical, but they explain metabolism really well. Both books speak to the science behind ketosis.

From what I've read so far (mid way through the performance book, finished the living one), ketosis is the act of burning stored and ingested fat. While glycogenesis only burns stored glycogen, which you only get by ingesting carbs. Carbs are stored in very limited quantities in the body and they are the go-to fuel for activities. Once you run out of that fuel, the body can revert to burning stored energy (FAT), but it takes a few days for the body to access these and while transitioning, you will be sluggish and feel crappy (keto flu). If you can get through that phase, then your body will start burning fat, both ingested and stored. Once you are burning fat, your body becomes more efficient at metabolism fat. Weight loss is often accelerated and if you are an athlete, endurance is often maximized as there is NO carb crash/hitting the wall. The body has much deeper fat reserves (something like 40,000g) vs carb reserves (2,000g), so you will have much better fuel available. I think this is what also contributes to the decreased appetite so many feel on this diet.

That means, to me, that once you get into ketosis, you should do everything in your power to stay there. Your body has cleaned out all the stored glycogen and is using fat exclusively for energy. The biggest issue here is that once you slip and ingest a high level of carbs, your body stores it immediately and you have to go through the whole process of eliminating it to get back to switching your body to using ketones as the main energy source. For folks on a weight loss path, this could stall your progress.

Ok, I wouldn't call myself a smarty pants at all, but honestly reading these books has helped me to much, much better understand the biology/science behind the Keto woe. I hope this helps, and I know there are a lot of way, way smarter people then me on this board who will also weigh in with their input. Just my 2 cents!