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Natural Foods Merchandiser

The carbohydrate conundrum

The second generation of low-carb diets—like South Beach and the diet advocated by Jennie Brand-Miller and three other nutritionists and physicians in their book, The New Glucose Revolution (Marlowe & Co., 2003)—make the glycemic index central to determining which carbs to eat. Overweight and obesity are not a matter of eating too many carbs, they say, but of eating the wrong kind of carbs.

are low-carbohydrate diets balanced?Given a choice between a carrot and a stick, most consumers would probably choose the carrot. That is, until the Atkins diet came along. Now reviled by some for having too high a carbohydrate content, the lowly carrot, long a staple in the dieter's arsenal, has sparked a debate not seen since George the Elder banned broccoli from the White House.

Shunning the carrot, however, is just an example of a good concept gone frighteningly awry, some say. While a medium carrot does have 7.3 grams of carbohydrates on average, according to Atkins—just shy of the 8 grams found in an ounce of baking chocolate—it also has fiber, which slows the absorption of glucose—the real culprit.

The second generation of low-carb diets—like South Beach and the diet advocated by Jennie Brand-Miller and three other nutritionists and physicians in their book, The New Glucose Revolution (Marlowe & Co., 2003)—make the glycemic index central to determining which carbs to eat. Overweight and obesity are not a matter of eating too many carbs, they say, but of eating the wrong kind of carbs.

With so much variation in how consumers look at carbs, the savvy naturals retailer would do well to understand the issues—especially because the South Beach diet advocates whole grains and rails against processed foods.

"Human beings have to have 50 percent to 55 percent low-glycemic carbs [in their diet], 25 percent to 30 percent fat, and the rest protein. We know that to be a fact," says Ann de Wees Allen, N.D., chief executive officer and chief of biomedical research at the Glycemic Research Institute in Washington, D.C.

Therefore, "If you're going to have a high-carbohydrate diet, 55 percent carbohydrate, there should be some attention paid to the kind of carbohydrates in your diet," says Thomas Wolever, M.D., a professor in the department of nutritional sciences at the University of Toronto, and one of the authors of The New Glucose Revolution.

The body's sweet revenge

With that in mind, here's a quick biology lesson: Carbohydrates are essentially chains of sugar that the body breaks down into glucose and, using insulin, transports the glucose out of the bloodstream to muscles and vital organs for energy. The more sugar that is released into the bloodstream, the more insulin the pancreas produces. If the body can't use all the available glucose, it stores the excess as fat. Furthermore, the carb-induced spike in blood sugar and insulin results in a corresponding crash, leaving the consumer feeling tired and hungry in short order, and seeking a quick fix—often of more carbs—to overcome the problem.

The vicious cycle can be interrupted, say strict low-carbers, by not allowing carbs into the bloodstream in the first place. They're the people who seek out the high-protein, high-fat, carb-free cookies and pork rinds.

Those who use the glycemic index say it's simply a matter of choosing carbs that break down more slowly and keep blood glucose on an even keel. Rather than buy specially formulated products, these consumers are more likely to buy brown rice and alternative sweeteners.

The glycemic index uses glucose as a reference point, assigning it a score of 100. A higher score means a particular food raises the blood-sugar level faster than pure glucose; anything lower is slower. (Note: Some diets use a slightly modified scale, where white bread equals 100.)

"We have been through the high protein, the low protein, the high fat, the low fat, and none of it makes any sense," says Allen of the Glycemic Research Institute. The glycemic index is the most valid measure of how "fattening" a food is, she says. "The most fattening food on the planet is a rice cake."

The return of real foods

Even dieters who eschew the carrot could instead be chewing it. Though GI ratings on the vegetable vary (Atkins gives it a 71; The New Glucose Revolution, a 47) most index advocates agree that its actual impact on blood glucose is minimal because of its high fiber and low carb content.

That's why good carbs tend to be fruits and whole grains, writes Arthur Agatston, M.D., author of The South Beach Diet (Rodale, 2003); bad carbs, he writes, are anything processed, since processing removes the fiber. Fats and proteins also slow down sugar release, and usually help create satiety. Good fats are the heart-healthy, monounsaturated kind, such as olive oil.

The only way to know a food's GI score for sure is to test it. Testing firms like the Glycemic Research Institute and Wolever's company, Toronto-based Glycaemic Index Testing Inc., have ascertained the GI value for some 1,000 foods, admittedly a small portion of the universe of foods. But don't expect that to remain unchanged.

"Based on what's going on, it wouldn't surprise me [if manufacturers begin] putting that information [on their products] voluntarily," says Phillip Harvey, chief science officer at the National Nutritional Foods Association. Some already are, though GRI is the only organization with authority from the U.S. government to label products according to their glycemic index, Allen says.

"Manufacturers are actually clamoring to get the seal of approval," she says—at least those who are confident their product will pass.

At a cost of $6,000 per product, some manufacturers, Wolever says, are "quite reluctant to pay a lot of money to get the food tested [only] to prove it's high GI." Some, however, have their products tested several times in hopes of hitting on a formula that allows them to make a low-glycemic claim. Increasingly, he says, manufacturers are adding lactitol (a sugar alcohol), fiber, pectin, inulin and a host of other ingredients to food to replace the carbs and lower the GI score. "This is a big thing," Wolever says.

Glucose: What a rush

Dieters aren't the only people using the glycemic index, either. It was initially developed in 1981 for diabetics, who must carefully control their blood sugar. Athletes also find it helpful. Depending on their sport, they may want something that provides a quick burst of energy (high GI) or a more sustained boost (low GI). "If you're an athlete and you're in a multiday event and you've just done your first day, you really want to get high glycemic [nutrition] in to replenish the [glucose to your] muscles," Wolever suggests.

Allen would like to see the federal government force manufacturers to put GI labels on their foods, but says the information needs to be clear. "A confused buyer doesn't buy."

That's one reason why, rather than place the numerical value on the label, GRI thinks it's more useful to label a product with the words "Diabetic Friendly," "Diet Friendly" or "Sports Friendly." Some of the foods that have received the GRI seal include U.S. Mills' Uncle Sam Cereal, Nature's First Coffee Creamer and Medifast Plus for Diabetics products, which include shakes and bars.

Size matters—to an extent

There are limitations to the glycemic index, though. For one thing, it doesn't tell you how many carbs are in a given serving of food. While quantity may not be the primary factor, as some diet gurus would have us believe, it does play a role. So researchers developed the glycemic load concept, which is a measure of the GI multiplied by the number of available (nonfibrous) grams of carbohydrates in a standard serving, divided by 100. So, something like watermelon, which has a high GI (72), has a low GL (4) since most of its weight is water.

Various factors, too, such as cooking, processing and variety, can alter a food's GI score, as can individual differences in metabolism—explaining the differing numbers published for the same foods.

There's no evidence yet that one type of diet is better than the others. When two low-carb and two low-fat diets were stacked up against each other in a year-long study, there was no significant difference in the amount of weight dieters lost. Michael Dansinger, M.D., of Tufts University New England Medical Center in Boston found that people on Atkins, the Zone, the Ornish diet and Weight Watchers all lost about 3 percent of their weight, regardless of which plan they followed.

Natural Foods Merchandiser volume XXV/number 1/p. 34, 36

The skinny on common foods

A food's glycemic index can vary considerably from its glycemic load




Medium apple



Medium banana



Black bean soup






Ice cream



Cheese pizza



Macadamia nuts



Peas, boiled






White rice, long grain



Brown rice



Wonder bread



Source: The New Glucose Revolution, by Jennie Brand-Miller, Ph.D.; Thomas M.S. Wolever, M.D., Ph.D.; Kaye Foster-Powell, M. Nutr. & Diet.; Stephen Colagiuri, M.D., Marlowe & Co., New York, 2003.


Natural Foods Merchandiser volume XXIV/number 11/p. 36

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