Health & Fitness

Our blood sugar (glucose) levels affect many aspects of our health, including cardiovascular health, diabetes onset and progress, hyper- and hypoglycemia, physical and mental performance, recovery from exercise, life span and quality, and how we feel at any moment. It varies significantly throughout the day in response to the clock, food, and exercise. We can't control the clock, and the effect of exercise on blood sugar is another story. But we can significantly and fairly easily influence blood sugar swings and their effect on all these factors, even if we eat a lot of healthy carbohydrates (as most of us should) or just have a sweet tooth.

In addition to their nutritional contents such as vitamins and fiber, many foods are now rated by their glycemic index (GI), a measure of how quickly and how high they elevate our blood sugar. The average blood sugar increase from a standard quantity of a food is compared to the increase from eating the same quantity of straight glucose (the sugar we absorb most rapidly) on a 0 to 100 scale, 100 being the GI assigned to glucose. (Teflon probably has a GI of 0, because it has no systemic effect on our bodies, as demonstrated by President Clinton, who, although obviously coated by it, has apparently displayed no effects other than convenient memory lapses and improved tap dancing skills!)

For simplicity, foods are generally grouped into three GI categories: low (under 55 on the scale of 100), medium, and high (over 70). And there are some surprises in the lists. For example, of the three following foods, which one has a high GI, which a medium, and which a low: low-fat tofu frozen dessert, table sugar, canned peaches?

Bet you're wrong. The can of peaches in natural syrup? GI = 30; very low. The straight table sugar? Just 65; medium. The tofu dessert? 115; off the top of the GI charts. You'll find many similar surprises in the GI lists, such as a baked potato with nothing on it but air, at 93, which drives our blood sugar up higher and quicker than a slug of table sugar.

How do we use the GI numbers to keep our blood sugar, insulin, cholesterol, and triglycerides down, and our cardiovascular system healthier? It's really fairly painless: we reduce our intake of high- and medium-GI foods or at least eat them with low-GI foods. The GIs add up by straight, simple arithmetic. A "serving" of something with a high GI of 90 eaten with a "serving" of a low 30 acts like two servings of a medium 60 in our bodies. (A "serving" here is defined as the amount of that food that contains 50 grams of carbohydrates, such as a large slice of bread.)

That doesn't mean a bite of low-GI beans will offset a meal of baked potato and white bread. Portion size matters, and using the GI charts for a while will quickly teach you to glance at a snack and make an educated guess whether its overall GI is acceptable. Acid content lowers GI, so drinking a glass of OJ with a high-GI food will help lower the snack's overall GI. Cooking also affects GI; cooking pasta beyond firm (aka al dente) raises its GI significantly by breaking it down artificially so we digest and assimilate it more rapidly. And processing (making white rice from brown, for example) significantly raises GIs by breaking foods down to expose greater surface area for more rapid assimilation.

One could go nuts and cook and eat with a calculator in one hand, a scale in the other, a fork in the other, and a GI chart hanging from the bill of the cap s/he bought just for that purpose. Some diet buffs weigh and calculate everything they eat down to half-ounces, but that has at least five fallacies. One, this ain't rocket science. Two, even if it were, there's still a lot we don't know. Three, both cooking and eating should be fun, not a pop quiz. Four, no two people or pods of peas are truly identical. And, five, lives like that are only marginally worth extending, in some people's opinions.

Controlling the GI of your meals and snacks requires neither a scale, a calculator, three hands, a cap, nor memorization of the GI list. If you eat a baked potato, for example, you need to offset that by eating an equivalent amount of low-GI fruit, beans, vegetables, etc. Heck, even a Snickers bar has a low GI -- which just emphasizes the need to include calorie, fiber and fat content in your food selection criteria as well. Keep a GI chart handy until you develop a feel for the GI of your favorite foods. Use it to guide you in planning meals and snacks and to modify your favorite food list if necessary. It's more a matter of how we combine our foods than what we eat unless your bedroom floor is knee-deep in Twinkie wrappers. And, of course, realize that overall calories still control our weight regardless of GI levels.

A web search on "glycemic index" finds many sources of GI information, much of it promoting special GI foods. We should ignore that and eat real food, but some sites do print GI charts. There's an excellent, thorough GI chart and brief GI tutorial at

Look at that chart now and notice that even most sweet fruits have low GIs. That's Mother Nature for you; she wraps most foods -- from nuts to grains to fruits to vegetables -- in balanced packages of nutrients tailored to present fiber, vitamins, minerals, fats, GI, and even flavors in the right proportions and wrappers to optimize their effect on our health. It's man who messes it all up by grinding real food into oblivion and manufacturing imitation food from the resulting paste, thus reducing our health for their profit.

We have genetic preferences for sweets and fats because our ancestors often had to survive for days on one meal, and those who caught and ate more calories lived longer. When man invented Twinkies and Wonder Bread -- both much easier to find and catch (and with much higher GIs) than an agitated wildebeest -- those genes began killing us. The explosion in heart disease that accompanied food manufacturing early last century is only recently slowing now that we've learned that manufactured food plus fat-and-sugar-seeking genes are killing us.

Read a book on the topic. They're interesting reading for those who care at all about their health, and will provide both data and motivation to add foods' GI to the fiber, calories, and fat content you already use in planning your meals. Two excellent books include Andrew Weil's Eating Well for Optimum Health (published by Knopf) and The Glucose Revolution by Miller, ( Marlowe), available at bookstores. (Both also address the folly and risks of low-carbo fad diets.)

The latter book discusses how athletes -- which we should all be for a few hours each week -- can use high GI foods to recover more quickly from heavy exercise. There's nothing like a mountain of pancakes swimming in high-octane syrup and smothered with tofu dessert -- followed as soon as possible by another dose -- to recover from a day of play, labor, or working out so you can repeat it tomorrow. Glucose tablets may work more quickly, but don't provide the same satisfied smile. (I'm not sure which is more fun: windsurfing every day or eating to windsurf every day.)

Accept it; eating right is initially complicated. But if this column can present the tips of healthy-eating icebergs in mere 1,200-word bites, you can take it from there with minimal effort. If you think it's all overkill because your uncle has lived on meat, potatoes, and cigarettes for 93 years, realize that for every person like your uncle there are thousands who died decades earlier than necessary precisely because they lived like your uncle but lacked his rare genetic protection. Remember that many fatal medical problems require both bad genes and bad habits, and we can control the habits.