If you're fat, and I am, one of the reasons probably is that your body didn't want you to catch on "fire." There is an overlooked relationship between fat, sugar, insulin, and the stress hormone cortisol.
Earlier this morning I was chatting with a friend. She and I were discussing the peculiar phenomenon of skinny people who get type 2 diabetes, and she asked me to post my understanding of how this could happen. I'd say that diabetes causes weight gain, rather than the other way around, and this is why:
Fat is a fire extinguisher. Sugar is what catches on fire.
It's not a literal fire extinguisher, of course. But it is possible for glucose (sugar) in the bloodstream to auto-oxidize, that is, to "catch on fire." This damages cell membranes everywhere blood flows. That's not a good thing. And to prevent this from happening, our bodies have fat.
Fat cells can absorb excess glucose from the bloodstream. They convert it into triglycerides. The fat cell takes three molecules of glucose, combines them with water, and there you have it, triglyceride.
Unlike glucose, which can cause problems everywhere it does, triglycerides are safely locked in fat (or liver or muscle) cells where they won't cause any problems. And fat cells have two safeguards to make sure their triglycerides don't easily escape.
The "pores" on the surface of a fat cell are large enough to let glucose in, but they are too small to let triglycerides out. Triglycerides have to be "liquified" into droplets that can squeeze out of the cell in the form of fatty acids. Then the fatty acids can travel to other tissues where they are "burned" to make energy, carbod dioxide and water left behind.
But the fat cell doesn't take any chances about releasing fatty acids before their time. The "liquidification" process requires an active form of the enzyme known as hormone sensitive lipase, or HSL, for short. No active HSL, no liquidification of fat, the "fat" stays in the fat cell lounging around on your waist or thighs or ample behind.
Here's the hard part. HSL doesn't work when your insulin (which is the hormone that puts sugars inside fat cells in the first place) is in high concentrations in your bloodstream. Essentially, a fat cell can't store fat and release fat at the same time.
And if you eat a lot of sugar, and you aren't diabetic, your body is going to compensate by producing more insulin. Eat sugar, store fat. Eat sugar, and you can't burn fat.
Stressing out about your weight makes it worse.
When you are stressed, your adrenal glands make cortisol. This stress hormone won't nudge the stored "sugar" in your fat cells, but it will make your liver give up glucose from its stores of glycogen, also a combination of glucose and water.
And what happens when your liver releases glucose? Your pancreas senses the increasing levels of sugar in your bloodstream, and uh-oh, releases still more insulin.
Insulin knocks at the door of your muscle cells, too, and they bar the door, so to speak, to keep from being flooded with glucose. (Remember that fire analogy?) Your muscles become more insulin resistant, so your pancreas does what? It releases still more insulin, of course. This makes your muscles still more insulin resistant.
Take a jog around the block to burn off a few calories, and what happens? Your sugars go up. The exercise stresses you, your adrenals release cortisol, your liver releases sugar, your pancreas releases insulin, and over time (it can take years, actually) the pancreas has to work harder and harder to accomplish less and less and diabetes eventually results. But your fat cells stay in fine shape.
If you are a diabetic, you're very aware of that.
Carol and I had a conversation on her observation that some people who are thin also become diabetic. This is more common among people of South Asian (Pakistani, Indian, Nepali, Bhutanese, Sri Lankan) descent. What's going on in these cases is, usually, that their fat cells are unusually small, and have relatively few receptors for insulin, and are relatively inefficient for clearing sugar out of the bloodstream. Only when sugar levels get quite high do individuals with this kind of genetics develop pot bellies, but seldom the overall fat that is common in us Hagar the Horrible type diabetics, like me.
So what can you do?
Relax. Aerobic exercise may not be your answer, although resistance exercise (which temporarily increases sensitivity to insulin by a factor of about 50) may be.
If you want to control your weight, that is, keep from gaining more, control your intake of carbohydrates, especially simple sugars.
And if you want to lose weight, sorry, gotta burn those fatty acids. Not only do you have to avoid overeating, so your fat cells can let fatty acids out, you have to do something that burns them. That's where your slow exercise comes in. Slow, long exercise. Hours at a time. Interspersed with weight lifting to correct the underlying problem.
You may ask me, if you're so smart, why haven't you done this? It's hard. But it's almost New Years. So it might be time to give it another shot. Comments are welcome.