Insights on Metabolic Syndrome

I've learned some really groundbreaking things about the body recently, and put two-and-two together to realize: the human body can't really process fructose; like, it really doesn't know what to do with it. And fructose alone (such as in high-fructose corn syrup) seems to have good explanatory power for America's ongoing obesity epidemic.

The tl;dr of this, is linking the Personal Fat Threshold theory to knowledge of how fructose is metabolized. If you already know about both of these, lightbulbs are probably going off in your head right now, and you could probably write this note yourself.

Blood sugar

1. Glucose and things that break down into glucose cause your blood sugar to increase. (basic stuff)
2. Fructose does not affect blood sugar levels (except in the unreasonable eventuality that your body is lacking glucose generally, and you consume pure fructose). Yet, fructose is sugar. Fools would say that this means fructose is healthier than glucose (no blood sugar spike == good, right?), but those people are wrong. In actuality, the fact that fructose, a sugar, does not increase blood sugar levels is an indication that our bodies are just not able to process it.
   

Metabolism

1. Every cell in your body can metabolize glucose and use it for energy.
2. Fructose can only be metabolized by the liver, and thence either into glucose or fat. But it only turns into glucose if you're low on that; and fructose sources almost always contain glucose, meaning that in practice, almost all dietary fructose turns straight into fat... right in the liver. More on this later, but suffice to say: fructose == bad, and I'd argue unfit for human consumption.
3. Sucrose (table sugar) is a disaccharin (two-sugar) consisting of 1 glucose and 1 fructose. Because sucrose contains fructose, it is bad for you; don't eat it.
4. Lactose is broken-down into galactose (if you have the right enzyme), and galactose is broken-down into glucose. Ergo, lactose is pretty okay.
5. Sugar alcohols are fine, and are (with the exception of erythritol) actually beneficial for your gut in extreme moderation: be careful with how much you eat (unless it's erithritol) or you might soon be shitting yourself like never before (à la Sugar-Free Haribo Gummy Bears). Also: be wary of eating them without a source of calories, lest you risk confusing your body/brain.

Bees & Honey

1. Bees can utilize fructose directly in their muscles, and they can do other cool things with it, too. For them, fructose consumption does not cause obesity. And this makes sense: nectar is largely fructose (I assume), and nectar is a bee's primary food-source during the growing season; so of course bees need to be able to process it well.
2. The honey that bees produce is, predictably, full of fructose. This is great for bees, and bad for humans. Honey is like Nature's high-fructose corn syrup. It's obviously not as bad as HFCS, and it indeed has some redeeming qualities for humans (thanks to bee enzymes and pollen grains), but if your honey is cooked or pressure-strained through a membrane, it is 100% bad for you, and you'd be better-off eating table sugar.

Fat

When your body fills up its subcutaneous fat stores and you're unable to make new adipocytes (fat cells) fast-enough, the adipocyes you do have start to swell up as the body force-feeds them fat.
This swelling forces some adipocytes so far away from blood vessels that they die of hypoxia (lack of oxygen), causing inflammation as the body's immune system tries to autophage the debris from the dead adipocytes... debris which is loaded with fat, fat which is then stuffed into the surviving adipocytes, which causes them to swell more, which causes other adipocytes to get cut-off from blood and die... repeat.
Your adipocytes don't like being completely stuffed all the time, and start trying to ignore insulin, a hormone the body makes to tell your adipocytes to take in fat. So, your body makes more and more insulin to force-feed these fat cells. This causes ectopic (in the wrong place) fat deposits to start developing: visceral fat, intramuscular fat, and more.
Once you have visceral fat, you know you have metabolic syndrome, because you really only have significant amounts of it when your subcutaneous fat stores are jammed past capacity.

And if you have visceral fat, you also know you are insulin-resistant, even if your A1c and fasting glucose are normal. You're pre-pre-diabetic, and your only saving grace is your pancreas, which is working overtime. Someday, when your pancreas just can't keep up anymore, you'll have diabetes.

Final notes

1. Fructose is not well-tolerated by humans, and, from what I'm seeing here, it's effectively a toxin at any dose and in any situation; and the more you have of it, the worse it gets.
2. I would guess that fructose is capable of causing you to store fat even in a calorie deficit.
3. At a minimum fructose is bad for your liver. If you have NAFLS (Non-Alcoholic Fatty Liver Syndrome), cut out fructose ASAP.
4. Don't eat fructose. Don't eat things that contain fructose (sucrose, HFCS, etc). If they have redeeming qualities (fruit, honey, etc), you can consider eating them in low amounts; but you're probably better-off getting those benefits from something healthier.
5. The human intolerance to fructose is a very clear sign that we are not frugivores. One more reason to not eat a fruitarian diet.
6. I'm pretty sure that countries where HFCS isn't widespread have (potentially universally?) noticeably lower rates of obesity than those where HFCS is the norm. Europe puts table sugar in its Coca-Cola. It tastes way better and should have probably half the fructose of American Cokes (assuming a 1:1 substitution of sucrose for HFCS). American Cokes used to be the same, and we Americans used to be healthier. I'm pretty sure that the time that HFCS was introduced was about when we started to balloon.
7. I'm inclined to think that consuming glucose (and by extension those compounds which metabolize into glucose: lactose, starches, etc) is actually fine and won't make you fat (or by extension give you diabetes) as long as you're getting enough nutrition and you're exercising enough to where your calories are balanced.
8. Contemporary research on glycemic index is potentially misguided if it isn't controlling for fructose in experiments, because the fructose (in sucrose) could have been what caused issues in non-control groups, only for those issues to be mistakenly attributed to glycemic index. Because fructose is so commonly combined with glucose, measuring the glycemic index should correlate strongly with fructose presence until you isolate the glucose and the fructose. So I wonder if researchers are distracted and chasing an invalid path because of this tight correlation. Then again, this entire point is entirely conjecture, because I haven't read research on this myself. Just to be clear: I don't want to imply that glycemic index doesn't matter; but I do want to stress the importance of disentangling the negative effects of blood-sugar spikes from the negative effects of fructose. Again, idek if this is an actual issue with current research; it's just something I'd be concerned about.
9. Just wanted to iterate: Visceral fat is a symptom, not a cause. I see it often said that visceral fat causes insulin resistance, but the latter must necessarily exist prior to the development of significant visceral fat deposits because the body preferentially stores fat in subcutaneous deposits and will only turn to visceral deposits after the subcutaneous deposits have become stuffed past capacity and have started trying to ignore insulin. As well: visceral fat is a kind of ectopic fat. I think the mainstream way of looking at visceral fat (ie, that it isn't ectopic) is wrong.
10. While fructose is pretty much just completely bad for you, some things that contain fructose can be worth eating if they have other benefits (ie, certain fruits). However, if you have metabolic syndrome... you need to be eating as little fructose as you possibly can; try to find alternatives to foods with appreciable levels of fructose.

Disclaimers

• I admit openly that my own knowledge here is quite (QUITE!) lacking. But sometimes, just sometimes, major insights can come even from outside the hallowed halls of academia. If this note puts a researcher down a beneficial path, even if it's not in agreement with what I've proposed here, that's an absolute win. I'd love this theory/conjecture/what-have-you to be proven false or true or other because that right there is yet more knowledge, another piece in the puzzle as we advance towards an ever-more complete picture of human health.
• I am not a doctor and this note should NOT be construed as formal medical advice! I wrote this to myself and decided to share it in case it might be helpful to others; that is all.