"When unproven science becomes a sales pitch, some people get rich and the rest of us get ripped off," Jeffrey Prince of the American Institute for Cancer Research told a news conference.

"Eating vegetables, fruits, whole grains and beans, which are all predominantly carbohydrate, is linked to a reduced risk of cancer, heart disease, stroke, diabetes and a range of other chronic diseases."

Prince said low-carb diets that advocate piling on the animal protein and fat are "increasing the risk of developing cancer, heart disease, stroke, type-2 diabetes and other chronic diseases."

The new group includes such organizations as the Alliance for Aging Research, the American Association of Diabetes Educators, the AICR and the American Obesity Association.

Its Web site at http://www.essentialnutrition.org/ is especially critical of programs such as the Atkins diet that advocate throwing the body into a condition called ketosis. During this phase the body sheds water as it tries to get rid of excess protein and fat breakdown products.

"Losing weight on these extreme low-carb diets can lead to such serious health problems as kidney stress, liver disorders and gout," the group advises.

The group published a survey of 1,017 adults, done by Opinion Research Corporation, that showed 19 percent of dieters are trying to cut carbs.

The survey found that 47 percent them believed that low-carb diets can help them lose weight without cutting calories.

"They are confused. They lack an understanding of the basic science," Barbara Moore, president of Shape Up America, told the news conference.

She said a "trickle-down effect" meant other Americans were now eating fewer fruits, vegetables, whole grains and low-fat dairy products." The U.S. government, American Heart Association, American Cancer Society, National Cancer Institute and American Diabetes Association all recommend getting at least five servings a day of fruits and vegetables. They also recommend eating plenty of whole grains.

The National Consumers League said it found dieters were spending an average of $85 a month on so-called low-carbohydrate products, although the U.S. Food and Drug Administration does not evaluate or regulate low-carb claims.

"Consumers are paying a premium price for a carb-friendly lifestyle," said Alison Rein of the National Consumers League.

She called for the FDA, U.S. Department of Agriculture and other agencies to issue immediate interim guidelines on such claims.

Studies show that a low-carbohydrate approach can cause people to lose weight more quickly than a low-fat diet for the first six months, but the low-fat approach catches up after a year.