Here's a great read from Crossfit Again Faster (a terrific blog): Disturbing Counsel.
Insulin is your internal UPS. When you eat, and your blood glucose level rises above 90 mg/dl, the pancreas kicks out insulin to start moving blood sugar and other nutrients around. Without insulin, you couldn't digest food; you could literally eat all you want, and none of it would reach the muscle cell, and you'd starve to death. Insulin, obviously, is a critical hormone.
Unfortunately, insulin is an equal-opportunity dump truck. It doesn't care what gets dumped where; it just looks for a big 'VACANCY' sign and fills accordingly.
When blood sugar's rising too fast or too high, the pancreas overreacts a bit. Insulin pours into the bloodstream, pushing blood sugar and amino acids,etc. anywhere possible. Unfortunately, this results in a blood sugar crash, because insulin doesn't know when to stop. So a few hours later, you're tired and hungry again. Long-term, your muscles become resistant to these insulin waves. That's diabetes, friend: the resistance of muscle to insulin.
How can you moderate the insulin response? Well, dull the sharp spike in blood glucose with proteins and healthy fats. Your blood sugar level won't rise as quickly, and the pancreas will release insulin in a controlled, orderly fashion. You can also cut back your total intake of carbohydrates (which are just complex or simple sugar molecules.)
This all sounds like a bunch of chemistry so far, so let's talk about how insulin levels affect YOU.
What's your typical breakfast? Cereal? Well, with enough milk, your blood sugar levels shouldn't rise too quickly. Not bad, but consider the type of cereal you're eating. If it's too sugary or processed, blood sugar levels will still rise too quickly; you'll secrete too much insulin, leaving you sleepy and hungry. Think that only kids' cereals are this way?
Here's a good story: Corn Flakes were invented by Dr. John Harvey Kellogg (yep, THAT Kellogg) to reduce sexual desire and cure the 'epidemic' of masturbation by lulling the eater into a lazy, unmotivated state. Graham Crackers were invented by Rev. Sylvester Graham to do the same. They weren't aware of the mechanism, but knew that carbohydrates would lull the eater into sedation. Kellogg, by the way, had a lot of other great ideas, including inflicting genital pain on kids to discourage overactive sexuality later.
One of the main reasons that diets don't work (at least, not for long!) is because they usually don't address the hormones behind the storage of fat and the insulin spikes associated with processed food. While most diets now recognize the value of 5-6 small meals per day, few acknowledge the goal behind frequent meals: controlled insulin levels. Instead, they choose to restrict carbohydrates, or proteins, or fat, or total calories. Take Weight Watchers, for instance: if you ate 6 small meals per day, and some of those meals were solely carbohydrate, your blood sugar spikes would make you store carbohydrate as fat. Likewise, on a strict Atkins diet, insulin levels are too low, and the protein isn't effectively used as energy. You CAN use protein for energy (gluconeogenesis,) but it's an inefficient process, especially without insulin to help.
Why the obesity epidemic? Why the skyrocketing rates of Type II diabetes? Look at our dinner plates. At least 2/3 is carbohydrate. A pasta dinner is ALL carbohydrate. What chance does your pancreas have to control insulin output? None. Look at the FDA: they're not only responsible for regulating intake of foods, but also selling crops. And which crop gets all the government funding support? Corn, full of fructose and a major insulin overstimulant. Corn is in everything: pop, bread, virtually any food containing fructose…even protein bars. What diet does the government recommend for avoiding heart disease? Low-fat (read: high carbohydrate.) What do doctors recommend for Type II diabetes – a totally reversible condition? Drugs. Not exercise (to raise insulin sensitivity in the muscle) or a balanced diet, but medication.
Clearly, no one is going to control insulin for you. It's up to you. This is why most Crossfitters follow the Zone diet (www.zonediet.com) – balanced protein and carbohydrate intake, moderate healthy fat intake. It's both beautiful in its simplicity and challenging enough to hold your attention. No, it's not controversial. It's even kinda boring. But it works.
If you don't want to listen to Dr. Sears, or buy his book, try this: eat protein at every meal. Eat denser carbohydrate sources at the same amounts as the lean proteins, or vegetables at double the volume of lean proteins. Eat a bit of fat at every meal. Here's a good starting point: eat a piece of lean chicken breast about the size of your palm. Eat a little pile of rice, about the same size. Eat a few almonds. If you feel sleepy an hour later, cut back on the carbs a bit next time, and try it again. Better yet, trade the rice for about twice the amount of salad.
Raise your insulin sensitivity with exercise: intervals, weights, and aerobic. Burn that diabetes candle at both ends. But keep it in check. You'll live longer, be smarter, and enjoy life more.