As Americans flock to low-carbohydrate diets to battle their burgeoning waistlines, food companies are rushing to fatten their bottom lines with a plethora of new lower-carb products.

In the first three months of this year, almost 400 new products touting low-carbohydrate claims have shown up on grocery shelves, compared with fewer than 300 for all of 2003. Consumers are expected to plunk down $30 billion for such products this year.

The products carry a jumble of labels designed to entice consumers, including “net carbs,” “carb friendly,” “low carb,” “carb lite” and “carb free.”

But what do those terms really mean?

That can be hard to determine, given the lack of carbohydrate labeling guidelines from the Food and Drug Administration. As a result, food industry watchers say, some companies are misleading consumers.

The FDA, at the behest of consumer and food industry groups, is working to devise low-carbohydrate guidelines, much as it did in 20 years ago when low-fat claims were all the rage. But such mandatory guidelines aren't expected until mid-2006 — at the earliest.

In the meantime, food companies must meet the FDA's standard back-of-the-package nutrition labeling rules. But when it comes to the front of packages, it's a free-for-all.

A report from the consumer intelligence firm Mintel International finds that half of all Americans have considered, have tried or are on a low-carbohydrate diet. A separate survey from Opinion Dynamics finds that of those on some sort of reduced-carbohydrate diet, 66 percent say it is “very or somewhat important to them that a food has a specific low-carb brand label on the packaging when making a purchase.”

And that's where fast-and-loose rules come into play, as there is no legal definition for many of the terms used on the fronts of packages.

For example, Atkins Nutritionals Inc, arguably the best-known name in the low-carbohydrate game, has a recognizable red, white and blue label advertising its products' “net carbs.” But what are net carbs? It depends on whom you ask.

Some say net carbohydrates are the total number of carbohydrates minus grams of fiber. Others go further and subtract fiber grams and sugar alcohols from their totals. Sugar alcohols — with such names as maltitol, sorbitol and isomalt — are neither sugar nor alcohol, but are sweeteners that have roughly half the calories of table sugar.

For example, an Atkins Morning Start Apple Crisp breakfast bar, which advertises 2 net carbohydrates on the front of the package, contains 13 grams of carbohydrates. Atkins subtracts 6 grams of fiber, 1 gram of sugar alcohol and 4 grams of glycerin — which isn't even listed on the nutritional label — to arrive at its net 2 gram number.

Gil Wilshire of the nonprofit Carbohydrate Awareness Council says such science is bogus.

“There's a lot of deception taking place in the food industry right now,” Wilshire said. “They're loading foods with sugar alcohol and saying ‘Atkins says you don't have to count it.' Alcohol sugars aren't strictly carbs but if you don't split hairs too thinly, they are carbs in general.”

Wilshire and others say that while table sugar has 4 calories per gram and has an impact on blood sugar levels, sugar alcohols also have an impact on blood sugar levels but to a lesser degree, usually at 2 calories or more per gram.

He points out that Atkins Nutritionals is a for-profit company bought late last year for an estimated $700 million and is partly owned by Goldman Sachs. It is estimated that Atkins last year had sales of $100 million.

“Ten, 15 years ago when Dr. Atkins said to ignore sugar alcohols, he meant the little bit that might be found in a grape, and that it's no big deal to discount that,” Wilshire said. “What has happened is that manufacturers are loading up on sugar alcohols and saying they have no impact.

“Our country is dying from obesity. I think it's a national security issue and a national disgrace.”

But Stuart Trager, chairman of the Atkins Physicians Council, disagrees with Wilshire's assessment of net carbohydrates.

“We feel very strongly that net carbs reflect accurate testing on blood sugar levels,” Trager said. “Our products are routinely tested and come out as labeled or lower. When you look at the impact of sugar alcohols on blood sugar levels it seems to be negligible.”

Yet, even Robert Atkins, who first published a book on his diet revolution in 1972, writes in a 1985 edition of his book in discussing food labels that “when hexitol or sorbitol is on the label just count it in your own mind as a carbohydrate because that's what it is.”

Karen Duester, president of Food Consulting Co., which works with food manufacturers on labeling, said that for many products and their labels, “it's creative marketing people at work, and the FDA has not done anything to stop it.”

“Many manufacturers are using the net carb term and others because so many of their competitors are,” Duester said. “They almost feel like they have to keep up.”

While some food companies see opportunity in the low-carbohydrate craze, food categories including bread, pasta, orange juice and potatoes have taken a pounding from what some characterize as a fad.

Some of those affected, including the Kansas City companies American Italian Pasta and Interstate Bakeries Corp., have been put on the defensive, and some have been more aggressive than others in addressing the changed landscape.

American Italian is manufacturing soy-based pasta for the Atkins brand and has introduced its own “reduced carb” pasta.

The reduced-carbohydrate pasta is made from semolina wheat, and a process developed by MGP Ingredients Inc. in Atchison, Kan., increases the protein and fiber in the pasta.

Therefore, the new product, like the company's other pastas, has 31 grams of carbohydrates per serving but is much higher in fiber, giving consumers a net carbohydrate count of 19 grams per serving and almost half the recommended daily allowance of fiber.

American Italian chief executive officer Timothy Webster said the new pasta was in about 40 percent of grocery stores throughout the country. He expects that figure to rise to 80 percent within 30 to 45 days. Then he said the company will start an aggressive promotion of the products.

Webster said the sales of the new pasta were going “swimmingly.”

“We think we're first to market and with a superior nutrition profile,” Webster said. “If America stays focused on carbs for 10 years, I think they will become better educated and learn about different foods and nutrition.”

Webster said American Italian put a lot of time and thought into how it would label its pasta and decided to use the term “reduced carb,” a concept that is pretty well accepted, Webster said.

Interstate Bakeries is also addressing the trend by introducing a line of low-carbohydrate breads and rolls.

On the regulatory front, the Alcohol and Tobacco Tax and Trade Bureau last Thursday laid guidelines for the use of “low carb” for alcohol marketing at less than 7 grams, while the FDA prepares to tackle the food labeling issue.

Virginia Wilkening, the FDA's deputy director in the office of nutrition products, labeling and dietary supplements, said the agency already has decided what terms to examine and will issue guidance in the defining of net carbohydrates.

If history is an indication, a direction can be gleaned from a July 20, 2001, letter to Morico Foods about its use of “carbolite” labeling on its products.

The letter cites several labeling violations, including the use of the label “zero carbohydrate” because maltitol, a sugar alcohol, had been omitted from the total carbohydrate count. Maltitol, the letter says, is a carbohydrate and must be counted.

While the jury is still out on reduced-carbohydrate diets, a recent study by the marketing research company NPD found that virtually none of the 11,000 people studied between 2001 and 2003 were cutting carbohydrates to the degree recommended by low-carbohydrate diet plans.

The study found that the average number of carbohydrates consumed was 128 a day — 145 for men and 109 for women. That's far less than the 300 grams recommended in the FDA's food pyramid, but still well above the 50- to 120-gram daily maintenance levelcalled for by the Atkins diet.

The FDA's pyramid is being revamped, and the new version is expected to recommend far fewer than 300 carbohydrates a day.

Recently, Atkins Nutritionals has run full-page color ads in national and large daily newspapers presenting its own food pyramid. Not surprisingly, the Atkins pyramid minimizes carbohydrates.

“We are in the process as a society of learning to be carb-conscious,” said Trager of Atkins. “We're all in favor of more research — we're on the early side of the learning curve.”