Good carbs. Bad carbs. No carbs at all? South Beach, Sugar Busters, Atkins, Weight Watchers, The Zone. USDA Food Pyramids - which one?
Type 2 diabetes. Heart disease. Apple shape vs. pear shape. Metabolic Syndrome. What to eat? How to eat? Conflicting information, confusing rules....
It's enough to give anyone a headache.
It shouldn't be that difficult to figure out a healthy eating plan, since almost all of the reasonable ones are based on some variation of the glycemic index. But if "they" made it simple to understand, "they" wouldn't be able to sell you lots of books and overpriced prepared food, right? A little knowledge, in this case, might be able to save you money. If my own example is anything to go by (and I believe it is), you'll feel better overall and you'll be doing your long-term health a major favor.
I'm going to start with a non-technical and very simplified explanation of food and how it affects human bodies, discuss how the glycemic index works and how it can help you with food choices, and what it means for your overall health and well-being. The end of the article offers a simple set of guidelines to follow, so if you aren't interested in the "why," skip ahead to the "how" and you'll be just fine.
How Food Works
In the very simplest terms, you eat energy in the form of calories. Food is broken down by the digestive system and converted into glucose (simple sugar). The glucose moves into your bloodstream and is carried to the cells; it then moves into the cells where it is used for fuel (current needs). Excess glucose, anything more than is needed for current needs, is converted into fat and stored for future use.
How does glucose get from the bloodstream through the cell walls into the cells where it's usable? A hormone called insulin produced by the pancreas is the answer. I'm not a biochemist, so I won't even attempt to explain all the technical hows and whys of the process.
I think in visual analogies: Glucose as a big burly guy, strolling rather aimlessly through the hallways of the bloodstream, and Insulin as the doorman who says "Right this way -- this is where you are needed, sir." Insulin opens the door and Glucose steps through.
When everything is in balance -- energy in = energy out -- traffic in that hallway moves smoothly, Glucose gets where he is going with a minimum of fuss, the doors open properly and all is well. Unfortunately, things aren't always in balance.
Diabetes, Insulin Resistance, and Excess Blood Glucose
There are two types of diabetes, generally called Type 1 and Type 2.
In Type 1, the pancreas stops producing insulin altogether. The big burly Glucose guys keep wandering the halls, packed in tighter and tighter as more of them enter the system through digestion but can't leave because there is no one there to open the doors for them. They crash around, bumping into walls and getting more and more grumpy as time goes on.
In Type 2, two things can happen: either the amount of insulin produced is too small or the body begins to be resistant to the insulin it does produce. In the first case, you have only a few doorkeepers working as fast as they can to open doors and get the packed Glucose guys out of the hallways. In the second case, the Glucose guys have grown very stubborn and don't want to go through the doorways; now it takes Insulin shoving them bodily through the doors. Maybe even two or three Insulin guys, where one was once enough.
In any of these cases, the result is the same: Angry, milling, shoving Glucose guys piled up in the hallways, banging into things and punching the walls. The kidneys try to help out by working overtime to flush out the excess glucose -- you get very thirsty to provide the extra water, and you need to pee almost constantly to get rid of that same extra water.
A continuing state of high blood glucose is very bad for the body. If you are Type 1 diabetic, you'll recognize the symptoms and take an extra shot because your own system no longer produces insulin. If you are Type 2, your pancreas will go into overdrive and produce more insulin as a response to the excess glucose. In either case, the extra Insulin guys will show up like the cavalry -- Ta DA! -- and shove all the Glucose guys into the cells where they belong to clear out the hallways. This is great!
Too Much of a Good Thing?
Or is it?
Now the overzealous Insulin guys have completely cleared out the hallways. Very few Glucose guys at all. The body's cells, needing a continual supply of glucose for fuel, begin to starve. You get light headed and feel spacey as your brain cells run out of fuel. You might begin to shake, or to sweat lightly regardless of the temperature. You might become nauseated. Eventually, if it's bad enough, your body will shut down temporarily to conserve fuel and you'll lose consciousness.
A Vicious Cycle
Before that happens, diabetics know to get something to eat or drink, something that will get the blood glucose levels back up to normal quickly -- orange juice, milk, a candy bar, or something else that is metabolized quickly. The problem is that there's a lag time of probably 20 minutes beween eating enough and feeling normal, so that it's far too easy to overeat, which spikes up the insulin again, which crashes the blood sugar again, which means you have to eat again, which....
To add insult to injury, when you overeat in response to low blood sugar, the excess glucose is sent into overloaded body cells by the excess insulin. Since the cells can't use all the glucose at once, they store it as fat. Not only are you potentially damaging your system by the constant spike-crash-spike cycle, you're packing on pounds as well!
There's Gotta Be a Better Way!
So obviously, what you want is to keep the system in balance. To have a steady supply of Glucose Guys to feed the cells and a steady supply of Insulin Guys to act as doorkeepers. Finally! This is where the Glycemic Index comes in.
The Glycemic Index is simply a measure of how fast glucose gets into your bloodstream after you eat a particular food. You can use the index to choose foods that release the Glucose Guys in a slow and orderly fashion, so that they saunter down the hall a few at a time over a sustained period of time.
Unfortunately, there is a minor catch. There are two competing Glycemic Indices, one based on table sugar = 100 and one based on white bread = 100. The same food will be either low, medium, or high on either index; just the numerical score will differ, in the same way that an air temperature just below freezing might be -2° C and 28° F at the same time.
When you see a list of Glycemic Indices for food, then, just make sure you note which baseline the list is using.
Using the Glycemic Index: Simple Rules
- Limit foods with a high glycemic index, eat them less often, and in smaller amounts. This is especially important if you are trying to lose weight.
- Choose more low glycemic index foods. Make these foods your primary food choice.
- Choose foods high in dietary fiber. Fiber helps slow carbohydrate absorption and glycemic load.
Here is a very simplified table showing some of the common choices available. For a more comprehensive table which lists the glycemic indices of a number of foods, download this PDF file.
One Last Rule
And it may be the most important: Watch portion sizes! Eating only low GI foods won't do you much good if you eat so many of them that your hallways are jammed with slowly sauntering Glucose Guys that will move into the cells and be turned into fat!
And finally, to get you started, a Low GI Recipe for your dining pleasure:
Mediterranean Chickpea Stew
* 2 tablespoons extra virgin olive oil
* 2 cloves garlic, finely chopped
* 1 medium onion, chopped
* 1 green pepper, chopped,
* 4 medium zucchini, diced
* 1 can (35 oz) whole peeled tomatoes, drained
* 1½ cups cooked chickpeas, drained (or 1 can, drained and rinsed)
* 1 tablespoon capers, drained
* salt and freshly ground black pepper to taste
* (optional) couscous or brown rice, cooked according to package directions
- Heat olive oil over medium heat in a large skillet. Lower the heat and sauté the garlic and onion for 5
minutes until translucent. - Add the green pepper and cook 5 minutes more.
- Add the zucchini and cook for 15 minutes.
- Crush the tomatoes as you add them to the vegetable mixture. Bring to a simmer and cook for another 20 minutes or until the zucchini is soft and translucent but still holds its shape.
- Stir in the chickpeas and capers and cook for another 5 minutes until the mixture is heated through.
- Season with salt and freshly ground black pepper to taste. Serve over couscous or rice.
Serves 4.
Additional resources and information on the Glycemic Index:
The New Glucose Revolution: The Authoritative Guide to the Glycemic Index by Jennie Brand-Miller et al
Includes 67 pages of tables listing hundreds of foods; cooking tips; menus, and 47 recipes. Paperback; list price $15.95.
Glycemic Load and Health Risk
Glycemic Index, Glycemic Load, Satiety, and the Fullness FactorTM
The Official Website of the Glycemic Index and GI Database