Low-Carb Diets Take a Punch

The partnership also includes the Alliance for Aging Research, the American Association of Diabetes Educators, the American Institute for Cancer Research, the American Obesity Association, the National Women's Health Resource Center, the Pennington Biomedical Research Center in Baton Rouge, La., the Society for Women's Health Research, the University of California-Davis Department of Nutrition and the Yale-Griffin Prevention Research Center in Derby, Conn. Some of these groups receive some corporate funding in addition to other grants.

The partnership offers this advice to those considering a low-carb approach to weight loss:

Beware quick weight loss Studies show that the fast, initial drop in pounds that occurs with extremely low-carb diets such as Atkins is mostly due to water loss caused by a metabolic condition called ketosis. "This form of weight loss is extremely stressful on the body and forces the brain to alter its metabolism," Moore said. "And it can't be ameloriated by drinking more water." And as the partnership noted, "research has shown that this weight loss cannot be sustained over time."

"We agree with that," said cardiologist Arthur Agatston, author of the South Beach Diet, which doesn't push its adherents into ketosis. "Even in advertising, we have asked the publisher not to make claims about rapid weight loss. We emphasize again and again slow weight loss, about one to two pounds per week, which is more-permanent weight loss."

Calories count. "The Atkins Essentials" says poultry, fish, shellfish, meat and eggs are foods that "you do not need to limit." It notes that exceptions are processed meats, such as bacon and hot dogs, that may be cured with sugar or contain fillers that contribute carbs.

The partnership noted that "a surprising number" of Americans are less concerned about the amount they eat than what foods they consume. "Contributing to this view is the growing belief [among those polled] that low-carb diets create weight loss without cutting calories, a view that the overwhelming number of credible scientific studies refutes." For example, a 2003 review article published in the Journal of the American Medical Association found that weight loss on low-carb diets is due to decreased calories. On the first two weeks of South Beach Diet, adherents are advised to eat specific menus that range from about 1,100 to 1,500 calories per day -- similar to traditional low-calorie diets.

"The monotony of the diets is a major factor in why people lose weight, because they end up being bored and eating less," the partnership noted.

Representatives for Atkins Nutritionals agree that their adherents consume fewer calories, but say it's because the combination of higher fat and protein is more satisfying to dieters.

"We have already demonstrated in studies that people end up eating fewer calories on Atkins," Heimowitz said. "They're eating about 1,400 to 1,800 calories per day is what studies have demonstrated" -- roughly what people are advised to eat on traditional weight-loss regimens.

On South Beach, "calories count, but counting calories doesn't work," Agatston said -- the reason that the program advises consuming healthy food in limited portions.

Eat healthy carbs. A national opinion poll conducted for the partnership in June found a lack of even "a rudimentary understanding of what carbs are and their role in the diet." The National Academy of Sciences recommends that Americans eat a minimum of 130 grams of carbohydrates per day -- roughly six times what is included in the induction phases of low-carb diets. The academy also noted, however, that most Americans eat two to three times more than they need. So reducing processed carbs makes sense for many people seeking to control their weight as well as for those aiming to choose better carbs: Highly processed carbohydrates, such as those found in sugary or white-flour baked goods are more likely to raise blood sugar and boost production of insulin.

Expect snap-back pounds. Research shows that as carbohydrates are reintroduced, rapid weight gain often occurs for low-carb dieters, the partnership noted.

"That's true, if you go into ketosis, " Agatston said. By eating too few carbohydrates, stores of glycogen are depleted. Eat carbs again "and you will snap back weight," Agatston said. "We don't find that [with South Beach] because we don't put people into ketosis."

In "Atkins Essentials," readers are warned that "the first week on Atkins may not be, punning aside, a piece of cake." At the end of the second week, the book guides readers toward deciding whether to stay in this first phase or to move on to one of the other three phases of the diet, which gradually reintroduces more carbohydrates, such as berries and whole grains, to guide dieters gradually out of ketosis.

Choose high-protein foods wisely. South Beach emphasizes fish, poultry and other protein low in saturated fat. But a survey conducted for the partnership found that half of those on low-carb diets are increasing consumption of steak and 30 percent are eating more bacon, which tend to be high in saturated fat. People on low-carb regimens are "eating more eggs and less cereal, fruit and dairy," Moore noted.

Read ingredients carefully. The average low-carb dieter spends about $85 a month on any number of the more than 1,000 products labeled low-carb, carb-smart, carb-aware, carb-wise or reduced-carb, or otherwise claiming to be carb-restricted. Yet there is no official or uniform definition of these terms, leaving food and beverage manufacturers free to apply their own. "While these foods are widely advertised and promoted, many of these claims are not regulated by the federal government, leading to confusion over what these labels mean," the parntership said, noting that consumers need to compare products carefully. •