Any useful information about glycogen would be helpful. I'm still learning!
From what I've put together, starch is mainly used for muscle glycogen while fructose is for liver glycogen. When you're liver glycogen is full, your body thinks it's well-fed so your metabolism and appetite increases. This can be used to keep blood sugar steady and provide brain energy. Muscle glycogen is used solely for the muscles.
So if one were to workout and use up the muscle glycogen, would the body turn to its visceral fat stores for energy?
Lately, I've had no appetite (like I feel no stomach hunger at 900 cal/day but tired so obviously this many cals is a no go) so would some more fructose and less starch increase my appetite, allowing me to feel good enough to work out, causing my body to turn to its fat stores and result in an optimal body shape? I haven't been eating much fruit lately, but quite a few sweet potatoes.
So is fructose the most necessary carb when active?
Another way I think about it is Grok had fruit and good liver glycogen during the summer when there are lots of animals around for meat and he can afford a high metabolism. Then in the winter, potatoes would be the main carb source. His metabolism and appetite would lower which would be beneficial since animals would be scarce. Since his muscles would then be able to use the muscle glycogen, he wouldn't deplete his fat stores until absolutely necessary. It's like an animal fattening up for winter. I'm starting to think the whole eating only seasonally foods rule is right.
Get Free Paleo Recipes Instantly
That's not entirely true. The liver will convert fructose to glycogen when its stores of glycogen are low, otherwise they become triglycerides.
Fructose, while it will increase your appetite, can damage the liver and lead to Non-Alcoholic Fatty Liver Disease when too much is consumed. You're better off with glucose from safe starches, or at minimum sucrose - and even then, not too much of it.
The summer fruit thing is true, but its purpose was to fatten up Grok for the coming winter. Safe starches were available year round, including the summer, so no, you shouldn't switch to just fruit in the summer. However, since you say you want to lose fat, and not gain it, this isn't a good path to take.
The only time tubers weren't available is in the deep winter when the ground froze over, and couldn't be dug. In the winter, potatoes weren't his main source of food, game was - if anything the winters were times of very low carb consumption. The other nice side effect of this is that the low carb intake caused his thyroid to produce more rT3/rT4 due to low carb and allowed for lots more sleep and lower energy states; not quite hibernation, but a similar idea. You'd also need to have plenty of cold exposure. As it's June right now, if you're in the northern hemisphere, this isn't really possible to simulate. You could do stuff like cold thermogenesis with cold showers and such, but it's not the same.
Muscles can also store FFA's the same way they can store glycogen, and burn them via beta oxidation for energy. You'll see these stores shrink when you enter autophagy, the excess tissue will start to be burned off during this time, and become less marbled internally and stronger.
If you were to use up your muscle glycogen, your fat cells would release more of its stores, your mitochondria would notice the available ketones and FFAs and eventually convert to burning them. But you'd also signal cortisol because this state puts your brain at risk, and cortisol is used to signal gluconeogenesis. Your muscles would become slightly insulin resistant so as to save the glucose for your brain.
What you're describing is attempting VLC for ketosis. It's fine to do this for short amounts of time, but you're better off at least getting 50g of carbs a day - and that number isn't from fructose, it's from safe starches.
If you want to force your body to burn fat, you'll have to consume fat, and you'll need to do HIIT and resistance training to signal your muscles to make more mitochondria, which in turn will make use of the excess fat stores more efficiently.
900 calories a day is stupid low.. especially if you're trying to gain muscle. Then, you want to eat fructose for fuel? At 2x that intake, I'm losing weight just sitting in a chair, haha. I usually do closer to 3x that amount.
Most of the common starches are high glycemic (unless you're eating something like super starch), where I don't quite buy into using that for steady blood sugar. In the winter, there's still fishing and cured / frozen meats without the need to dig up fibrous / resistant-starch filled tubers. (Grok didn't eat Russets.)
Imo, fructose is completely unnecessary in your diet, and borderline toxic if you're trying to fuel off the stuff. It is not an essential nutrient, nor is it required for an active lifestyle.