A couple of you have made me aware of the affect caffeine can have on insulin uptake. When it occurs in coffee, it does not have this problem; but when it occurs as an extract, as we would find in pill form,
it can decrease insulin uptake, with the effect of raising blood sugar levels. The study mentioned here did not test soda -- an interesting omission -- but the implication is that soda could also be harmful to those with insulin problems.
This is distressing because many people have been using diet sodas to avoid the problems caused by sugar in regular soft drinks.
Soda will increase your appetite (and in addition the carbonation can weaken your bones).
On the other side of it, there is research to show that bleached refined wheat and added sugar cause another part of the loop that forces people to be hungrier and eat more. This is from a famous article by Gary Taubes which ran a few years ago in the
New York Times,
"What if it's All Been a Big Fat Lie?"The answer provided by Endocrinology 101 is that we are simply hungrier than we were in the 70's, and the reason is physiological more than psychological. In this case, the salient factor—ignored in the pursuit of fat and its effect on cholesterol—is how carbohydrates affect blood sugar and insulin. In fact, these were obvious culprits all along, which is why Atkins and the low-carb-diet doctors pounced on them early.
The primary role of insulin is to regulate blood-sugar levels. After you eat carbohydrates, they will be broken down into their component sugar molecules and transported into the bloodstream. Your pancreas then secretes insulin, which shunts the blood sugar into muscles and the liver as fuel for the next few hours. This is why carbohydrates have a significant impact on insulin and fat does not. And because juvenile diabetes is caused by a lack of insulin, physicians believed since the 20's that the only evil with insulin is not having enough.
But insulin also regulates fat metabolism. We cannot store body fat without it. Think of insulin as a switch. When it's on, in the few hours after eating, you burn carbohydrates for energy and store excess calories as fat. When it's off, after the insulin has been depleted, you burn fat as fuel. So when insulin levels are low, you will burn your own fat, but not when they're high.
This is where it gets unavoidably complicated. The fatter you are, the more insulin your pancreas will pump out per meal, and the more likely you'll develop what's called "insulin resistance"... In effect, your cells become insensitive to the action of insulin, and so you need ever greater amounts to keep your blood sugar in check. So as you gain weight, insulin makes it easier to store fat and harder to lose it. But the insulin resistance in turn may make it harder to store fat—your weight is being kept in check, as it should be. But now the insulin resistance might prompt your pancreas to produce even more insulin, potentially starting a vicious cycle. Which comes first—the obesity, the elevated insulin, known as hyperinsulinemia, or the insulin resistance—is a chicken-and-egg problem that hasn't been resolved. One endocrinologist described this to me as "the Nobel-prize winning question."
Insulin also profoundly affects hunger, although to what end is another point of controversy. ...
David Ludwig, the Harvard endocrinologist, says that it's the direct effect of insulin on blood sugar that does the trick. He notes that when diabetics get too much insulin, their blood sugar drops and they get ravenously hungry. They gain weight because they eat more, and the insulin promotes fat deposition. The same happens with lab animals. This, he says, is effectively what happens when we eat carbohydrates—in particular sugar and starches like potatoes and rice, or anything made from flour, like a slice of white bread. These are known in the jargon as high-glycemic-index carbohydrates, which means they are absorbed quickly into the blood. As a result, they cause a spike of blood sugar and a surge of insulin within minutes. The resulting rush of insulin stores the blood sugar away and a few hours later, your blood sugar is lower than it was before you ate. As Ludwig explains, your body effectively thinks it has run out of fuel, but the insulin is still high enough to prevent you from burning your own fat. The result is hunger and a craving for more carbohydrates. It's another vicious circle, and another situation ripe for obesity.
High Fructose Corn Syrup is a particularly evil link in this chain. Corn is subsidized by the US government, so corn sweetener is cheaper than sugar. This stuff has been finding its way into everything; I've recently seen it listed as an ingredient in some solid foods.
What I've noticed is that virtually all of the food you will find in supermarkets or in fast-food restaurants is based on or involves highly-glycemic carbohydrates. Try to find something without added sugar, corn sweetener, corn, potatoes, rice, or refined wheat, and you'll see what I mean. To avoid these foods you invariably have to pay more, and you have to avoid a lot of foods you've probably come to like. High-fiber foods rarely go on sale. So there is a monetary incentive also to play into the insulin-hunger cycle. If you buy soda to drink along with your meals, you feed the cycle yet again.
If all of this is true, then it explains quite succinctly the "epidemic of obesity" which you hear about all the time. The conventional wisdom is that what causes this is high-fat food, but Americans eat less fat now than we did 20-30 years ago (and less fat than the average European), but we have increasingly put on weight. A massive diet industry has grown up around the issue, pushing expensive low-fat, high-carb foods -- which may contribute more to the problem than they solve. Dieting has become hell because you have to severely restrict your caloric intake while you are consuming more foods that are going to make you feel hungrier.
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