From The Urbach Letter –
Index. What You Need to Know.
Black or white. On or off. Up or down. Some things are binary. They’re all one way or the other, with no middle ground. Smoking is like that. There’s no safe level of cigarette usage. Just a few cigs a day will have a very dramatic negative effect on your health. But what about eating carbs? Is there a “safe” level? Of course there is. Carbohydrates are our main source of “fuel.” They provide us with the energy we need to function. Without carbs, we feel low energy and cold in the winter. That’s the main problem with ultra-low carb diets: no fuel. When there are no carbs around, the body is forced to burn protein and fat for energy, a much less efficient process. It’s the difference between throwing a tinder-dry log on the fire, and trying to burn an old soggy shoe. Don’t get me wrong, fat-burning is a very good thing. That’s how weight loss occurs, and the reason why Atkins, Zone, and the other low-carb regimes have become so popular. They work. However, as you read in the July Urbach Letter, newly released studies have shown that weight loss (which nearly all of us are interested in) occurs because of an overall reduction in calories, rather than from a reduced level of carbs. Eating protein and fat is satiating. It makes us feel full. Therefore we eat less overall. Relatively simple. But not healthy. Atkins is a *diet* not a lifestyle. Most people stay on a diet for a while, lose some weight, then eat “normally” again and gain it right back.
Personally, I’m not interested in yo-yoing via the diet route. I’m looking for a healthy lifestyle that will help me live to 100+ and help me look good while I’m getting there. That’s why I’m interested in Glycemic Index. All carbs are not created equal; some are digested very quickly and some very slowly, while others fall in the middle. Glycemic Index (GI) is a measure of how fast a kind of carbohydrate food is digested and its sugars released into our bloodstream. On a molecular level, all carbohydrates are built out of long chains of simple sugars. When digested, the bonds are dissolved, and the starchy bagel reverts back to simple sugars. Foods with a low GI have strong bonds. The conversion to sugar therefore takes a long time. Foods with a high GI produce a nearly instantaneous rise in our blood sugar (the “sugar rush” from a Krispy Kreme). That’s bad. A sharp rise in blood sugar provokes overproduction of insulin, a resulting wild swing in blood sugar level, and therefore more hunger. It’s like tossing a dry piece of construction wood into the fireplace. It will burn hot and fast, but quickly die down, requiring you to add even more wood to keep the fire going. Meanwhile, the short but intense flash of heat could have even damaged the fireplace bricks. Low GI foods are more like the well seasoned oak log that will burn slowly and steadily for many hours, releasing its heat and energy safely. Low GI carbohydrate foods are satisfying and naturally suppress appetite. Here’s how to find them.
GI is measured on a scale of zero to one hundred. As you might guess, pure liquid glucose has a GI of 100. But there’s no “bright line” between good and bad. It’s a grey scale. However, in general, GI’s below 55 are considered low, 56 to 69 medium, and above 70 high.
Higher GI Foods
Bread. Whether baked from refined (white) or whole-wheat flour, all breads have a GI of around 70. Bagels aren’t any better.
Rice. White rice ranges from 50 to 60. In general, the stickier the rice is, the higher its GI. Brown rice has a slightly lower GI, but not by much.
Pasta. White pasta cooked al dente has a GI of 40 to 50. “Chef Boyardee” type canned pasta is much higher, about 70.
Potatoes. 85. Wow. Now you know why French fries and potato chips are so fattening. Let’s see… why don’t we take a super-high GI food, soak it in oil and fry it?
Lower GI Foods
Leafy vegetables, tomatoes, and cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, etc.) have GI’s of 10 or less.
Non-tropical fruits. Apples, pears, peaches, apricots, kiwis, etc., range from 30 to 50. Unfortunately, tropical fruits like banana, pineapple, mango, and watermelon can range from 50 to 70.
Citrus fruits. Oranges and grapefruits come in at about 40.
Legumes. Beans, peas, and lentils have GI’s under 30. Peanuts are low at 14. Cooked pearl barley is about 25.
If you’re researching this topic further, you may come across a term called Glycemic Load (GL). While GI measures how fast food sugar is converted into blood sugar, GL measures how much food sugar there is to begin with, in the thing you’re eating. So, while watermelon as a relatively high GI of 72, it doesn’t contain all that much carbohydrate to begin with, so its GL is only a 4. GL is found by starting with the number of carb grams in a serving, multiplying that by the GI, and dividing by 100. Some consider GL more important than GI, but I think it’s mostly common sense. If you eat a baked russet potato, with a high GI of 85, that weighs nearly a half pound, you intuitively know it’s going to hit you hard (for number crunchers, its GL is 26). GL’s under 10 are considered low, while a GL over 20 is quite high. By the way, a bowl of corn flakes has a GI of 80 and a GL of 21.
I love corn flakes. And potatoes. And a lot of the other high GI foods. I haven’t stopped eating them altogether, but I’ve reduced the amount I’ll eat. For good health, current dietary guidelines call for about half your total daily calories to come from carbohydrates. Of these, I strive to have at least half come from low-GI sources. As usual, the advice: “Everything in moderation” makes the most sense.