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Low-Carb Foods: Less Than Meets the Eye

A few years ago the cry was "low-fat" or "nonfat," as new food products came on the market positioned to appeal to the weight-conscious and health-conscious. You could avoid most fat but still eat your ice cream and cookies. In some ways the trend to low-fat and fat-free foods was beneficial; in other ways it was not. Nonfat milk is a good thing, but nonfat junk food is still junk food, of course. Many consumers failed to notice that a low-fat cookie often has as many calories as the regular kind, and many assumed it was okay to eat the whole box.

Now the craze is for low-carbohydrate foods. If you’ve been to the grocery store lately, or even to McDonald’s or Blimpie, you’ve seen promotions for "low-carb" foods. Many breads, sandwiches, muffins, pasta, cereals, tortillas, pizza crusts, beer, cakes, cookies, and other foods now bear "low-carb" labels. While the health claims are seldom spelled out, the implications are clear.

If you’re following a low-carb diet (such as Atkins) that forbids or severely limits bread, pasta, and other starchy foods, especially those made with white flour, you might think, well, here’s a way to eat some bread and still stay on the diet. Indeed, many low-carb products are sold under the Atkins brand name. Or perhaps you’re not on any diet but are just calorie-conscious. You may conclude, logically enough, that a food lower in carbs is also lower in calories. Or you may buy the new stuff because you’re attracted to new products, and you think that there’s a law against false claims on food labels, so you conclude that low-carb claims must be (a) true and (b) meaningful.

In fact, "low-carb" is not what it seems. And any benefits these foods might offer for weight loss or nutrition are debatable, at best. If you replace carbohydrates with protein (that’s the main change), you still have just as many calories. Furthermore, the labels are, essentially, meaningless. The FDA has no definition of "low-carbohydrate" and has never approved any low-carb labels. Any food can be so labeled.

Bringing down the carbs

Here’s how manufacturers reduce the carbs in various foods:
n They replace refined wheat flour with soy flour (higher in protein), soy protein, or wheat protein.

• They add extra fiber, such as wheat bran, oat bran, or other fiber (this is not a bad thing, but read on).

• They add high-fat ingredients such as nuts (again, not so terrible: nuts are good food, containing healthy fats).

• They replace sugar with sugar alcohols (maltitol, lactitol, or sorbitol) or artificial sweeteners. This has been going on a long time—ever hear of sugarless or "dietetic" candy?

• For beers, they use certain chemicals in the brewing process to reduce carbohydrates in the brew. But the result is not very different from "lite" beers, long a market staple.

Is the difference real, though?

None of these changes are unhealthy. But these products end up having nearly as many calories as their regular counterparts, and cutting calories is still the key to weight control. Protein has as many calories as carbs do, and fat has more than twice as many calories.

The products often have nearly as many carbs, too, but the labels disguise this fact with several tricks. Most often they subtract certain carbs, and provide a separate section listing a lower number, which designates the remaining ones "effective carbs" or "net impact carbs." The idea is that since fiber, for instance, doesn’t affect blood sugar the way other carbs do, it doesn’t count. So if a food has 10 grams of carbs, but 6 grams are fiber, the manufacturer simply subtracts the 6 and claims only 4 "net impact" carbs. (Sometimes the results are clearly impossible. Some low-carb bread labels, for example, claim that nearly all the carbs are fiber, yet the first ingredient is always some sort of flour—a source of "regular" carbohydrates.) The calories in sugar alcohols, too, can be subtracted, according to this logic, because they don’t have the same effect on blood sugar as regular sugar. None of this is allowed by the FDA.

This sleight-of-hand can distract you from an accurate comparison between low-carb foods and conventional ones. Here are just three examples:

• A slice of "low-carb" Atkins bread, for instance, has 60 calories and 8 grams of total carbs, though it claims to have only 3 "net impact" carbs. A slice of a conventional "diet" bread typically has 50 calories and 10 grams of carbs. That isn’t a significant difference.

• A 1-ounce low-carb chocolate bar has 155 calories and 12 grams of fat, but no sugar; it claims to have only 1 "net impact" carb. A regular bar has 150 calories and 10 grams of fat. (Some choice!) Low-carb candies are actually pretty much the same as the sugar-free candies that have been on the market for years.

• A 12-ounce can of Michelob Ultra ("low-carb") has 95 calories and 2.6 grams of carbs. Miller Lite has 96 calories and 3.2 grams of carbs. Coors Lite has 102 calories and 5 grams of carbs. The differences are tiny. In effect, what’s new is the label, not the product.

No way to tell

Another problem: there is no legal definition of a low-carb food. The FDA has defined "low-fat," for instance, but any food, even Wonder Bread, can be labeled "low-carbohydrate." Moreover, fiber is supposed to be listed as part of the carbohydrates—not subtracted from it. The FDA does not define nutrients according to the effects they have on blood sugar, and for good reason. As we explained last month in our article about the glycemic index, these effects vary widely, depending on what’s in your entire meal. There simply isn’t any accurate way to calculate it for a food label. In any case, there is little or no evidence for the claim that some types of carbs are more likely to cause weight gain than others just because they affect blood sugar faster.

One good idea buried in the low-carb craze: It is better to choose high-fiber products over those made of refined wheat (white) flour. But that’s hardly a new idea. If you want more fiber in your bread, there are lots of good conventional choices, made of whole wheat or other whole grains, on the shelves.

Less costs more, and tastes worse

And then there’s the question of price. Low-carb almost always means high price. Low-carb beers cost more than lite. One low-carb breakfast cereal costs nearly four times as much per serving as regular cereals. Atkins breads cost twice as much as most regular breads. And most low-carb foods sacrifice a lot in taste and texture. (Not the candies, apparently, where chocolate flavors mask a lot.) Maybe this is a good thing—people will eat less of these foods, and the fad won’t last.

In the meantime, our advice: Don’t be fooled by low-carb foods. There’s no evidence that they’ll help you lose weight. They are not significantly more nutritious or less caloric than many regular foods. And they eat up food dollars better spent on plain good healthy foods such as fresh fruits and vegetables.

UC Berkeley Wellness Letter, January 2004