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Low-Carb Backlash?

From Atkins to South Beach, the popularity of low-carb diets is exploding all across the country.

Keith Ayoob, a spokesman for the American Dietetic Association, stopped by The Early Show to help separate health from hype.

An estimated 15 to 30 million Americans are currently trying to lose weight on low-carb, high-protein "fad" diets. Ayoob says low-carb products and shops, specialized restaurant menus, Web sites and cookbooks are abound. And it seems everyone knows someone who has a low-carb diet success story these days.

Low-carb diets such as the Atkins diet and the South Beach diet restrict most carbohydrates and allow fats in the restrictive first phase of the diet, Ayoob explains. They reintroduce limited amounts of certain carbohydrates in the second phase. Ayoob says a carb-deprived body will burn fat instead for energy.

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The latest studies show that you can achieve weight loss with these diets, but, in the long term, the success rates were not different from people on a more traditional diet, says experts. Research shows that a low-carb diet has no short-term bad effects on cholesterol, glucose, insulin or blood pressure. There is no real long-term evidence for the risks or the value of this kind of diet. Ayoob says experts can't say for sure that it offers any benefits.

Among obese patients, weight loss is linked to long-term compliance to the diet rather than the number of carbs cut. Ayoob says many people in the studies apparently had trouble staying with the low-carbohydrate diet and there were many dropouts. Twelve months is an equalizer. Dieters hit a wall. Your lifestyle starts to be affected and you get bored, he explains. A high dropout rate is a sign that extreme diets can be difficult to maintain. People start to realize they don't want to avoid their favorite foods, even in small amounts, for a long period.

Parts of a low-carb diet are fine, Ayoob says. Most promote consistent meals, lean proteins and vegetables. That part, however, is not a whole lot different than what people have promoted for a long time. The problem also is that the diets tend to emphasize extreme eating of one kind or another, and that can lead to bad habits in the long run.

Ayoob says any extreme in one's diet lends itself to abuse that can be unhealthy. For instance, if you hold out on carbs of any kind all day and then eat a large amount all at once, that is not dieting. Ayoob says it's overeating. And the exclusion of carbs such as fruits and vegetables that contain essential vitamins, minerals and antioxidants is not healthy either. They may also be important sources of energy. Ayoob says the bulk of research on diet and dieting shows that it's the amount of calories that you eat that is most important when it comes to losing weight, not the types of calories you consume.

The tried-and-true proof in dieting is that balanced nutrition, reducing calories to a healthy level, and getting physical exercise all result in weight loss. It's a question of how much and how often you eat. Losing weight is all about calories and there's a lot of ways of doing that, but the more restrictive the calories get, the harder it is to stay with it, according to Ayoob.

There is no magic bullet for safe and healthy weight loss, he warns. Anything that promises speedy results is not something that's generally recommended. You shouldn't lose more than one or two pounds per week. If you're losing more, you're either losing fluid or muscle mass and that can be dangerous.

The American Dietetic Association recommends achieving healthful weight that can be sustained over a lifetime, and supports the National Academy of Sciences guidelines that adults obtain 45 to 65 percent of their calories from carbohydrates, 20 to 35 percent from fat and 10 to 35 percent from protein.