*Just a reminder, as of right now, I'm just a hobbyist who does a lot of research.
In a previous post, I said "it metabolizes straight into fat." Its doesn't literally turn straight to fat. There is a complex process the body goes through to break down sugar.
Come on, its good for you!
No. You derive no real nutritional value from sugar- no vitamins, no nutrients. Yes, it offers glucose, but you can get that elsewhere.
How does it work? Break it down for me. (pun intended)
Sugar, aka sucrose, is made up of 2 molecules: glucose (appx. 80% of the glucose is used as fuel by the body, appx 20% heads to the liver) and fructose (can only be metabolized in the liver). The fructose effectively turns into fat.
But aren't there natural forms of sugar, too?
Yes there are! Sucrose, fructose, and/or glucose can be in fruits. You'll notice that it seems the same as table sugar, BUT the difference is usually the absorption rate (Hey, thanks a mil, fiber!!) As I understand it, the comparatively complex nature of the fruit, means that it metabolizes slower, thus curbing the impact on blood sugar levels. AND you get vitamins and nutrients and antioxidants and deliciousness from fruit!
Back up. You said +/-20% of the glucose goes to the liver. Is that turned into fat?
Ok, this is where I start to get a little confused. I know there is this thing called glycogen, so I did what any reasonable adult would do: I Googled "glycogen" and "kids" to find a suitably dumed-down definition. Here we go: That extra 20% heads to the liver to be put into storage. The body is basically like "We have all we need for the moment, the rest of you hit the waiting room and we'll get to you as soon as possible." Then a bunch of the glucose then heads to the muscles to wait until it is summoned (the rest hangs in the liver), and notices that there are a bunch of other glucose-friends hanging there, too! They decide to hold hands, and that group of glucose molecules is now called glycogen (yes, I realize this sounds a lot like Pokemon evolution).
Now, say you decide to go to the gym before breakfast... or you grab only a small snack. This is the time when the glycogen is like "It's time to GTFO- body needs me!!"-- they break the tender hand-holding, and head off into the blood stream so you can kill it on the treadmill (or at least that is how I understand it).
[Its important to notice that all the "glu" names are kinda energy sources]
You didn't answer my question. What is the relationship between glucose/glycogen and fat?!
Right. Again, a confusing topic. From what I understand, your muscles and liver have a "glycogen max capacity." Picture this: your liver has told the glucose to go to the waiting room. The liver is at glucose capacity (at this point they're all super-close, holding hands, and now called glycogen). The rest of the glucose molecules hop onto the Blood Stream Expressway, just to arrive at their muscle destination and realize.... there is no more room for them! WTH? So they're all hanging out in the blood trying to figure out where to go. So in rushes insulin who is like "I know where we can go!" and they go to the fat cells, where they're stored as body fat.
OMG! So once they turn to the dark side (no-shame Star Wars ref), are they trapped there foreva?
There is redemption! My research has taught me that thought the process to get that stored energy (glucose) is not the exact reverse of how it is made. I'm a little too fuzzy on the process to feel comfortable trying to summarize it.
It seems that the body will always want to use the newest (most recently digested) form of energy first-- which is totally logical, because its the easiest to access. However, say you're a typically healthy eater who goes for a candy bar and scarfs down nearly whole thing (me yesterday). I can almost guarantee that a good portion of that was swept to the fat cells by insulin (I had a relatively sedentary day and a slightly higher carb intake than usual because I feel crappy). Now today, I bet my body is going to be using the pb & banana oatmeal I had for breakfast for energy. If I get to the gym or decide to have a light lunch, then maybe some of the candy bar energy will be spent.... IF my liver and my muscles run out of glycogen.
The phrase "everything in moderation" seems a little.... inefficient. I think "everything scheduled" is more appropriate. If I want that candy bar later today, I need to make sure that I'm consuming relatively low levels of food that will convert to glucose--- because I want that glucose to be turned into glycogen, and I want to make sure the glycogen stores don't overflow too much, forcing the extra glucose into fat.
[And that, my friends, is my understanding of how the body deals with sugar. I know the processes are much more complicated than I have laid out, but I think I got the basics down!]
Now, give your brain a break and watch this is a cute little vid with a little interesting info about the sugar in soda vs. fruit.