Controversy Surrounds Carbohydrates in Dieting

For the millions of Americans trying to lose weight, the familiar message has been to eat less fat and more carbohydrates. But experts say this shift to pasta and potatoes has potential problems.

ABC's World News Tonight medical correspondent John McKenzie reports that experts believe many Americans have gone too far in the switch to carbohydrates.

According to Lisa Tartamella Kimmel, registered dietician at Yale-New Haven Hospital, when it comes to eating right, many people may have been receiving mixed messages.

"The intention of the 'low fat, high carbohydrate' message was to encourage Americans to reduce their excessive fat intake, particularly saturated fat, and consume more carbohydrates from fruits, vegetables and whole grains," Kimmel says. "The message was not 'do not eat fat' or 'eat all of the fat-free and low-fat carbohydrates that you want.' Somehow in the whole process, the message of moderation was ignored."

Too Many Carbs?

Experts agree that carbohydrates themselves aren't necessarily a bad thing, just that Americans need to know the problems associated with eating too many of them.

"There is nothing wrong with carbohydrates, they're a major staple in the diet," says Dr. Robert Eckel, chairman, American Heart Association's nutrition committee.

"The issue here is kind of misinterpreted. People gain weight because they eat too many calories, not too many carbohydrates. So the bottom line is, gaining weight is not attributed to carbos or fat," Eckel adds.

But Dr. Walter Willett, chairman of the department of nutrition at Harvard School of Public Health, explains it's not only the amount of carbohydrates you eat, it's also the type that's important.

"What's become quite clear is that not all carbohydrates are the same," says Willet. "When we eat a baked potato, we get a more rapid spike in blood sugar than we do even after eating pure table sugar."

Willett believes that eating too many carbs that are refined or in the form of sugar can make it difficult to control weight because they're quickly absorbed, sending blood sugar levels soaring, followed by high surges of insulin.

"After two or three hours, the large amounts of insulin bring the blood sugar levels crashing down, sometimes even below normal levels," says Willett. "At this point, people feel strong urges to look for snacks well before the next meal. Over many years, these powerful surges of insulin exhaust the pancreas to the point where diabetes can develop." Willett points to fat-free breakfasts, such as a bagel and jam, as foods that can cause this type of problem.

Eckel disagrees, and points out that "literature suggests higher-fat diets can cause more insulin resistance."

Elizabeth Ward, registered dietician and former spokesperson of the American Dietetic Association, says that when you eliminate fat from your diet, you need more carbohydrates to fill the void. But some carbs may be better for you than others.

"Clearly, whole grains are the good guys. We do eat too many refined carbs such as white bread," adds Ward. "However, I refrain from slamming single foods, including potatoes. Here we are trying to get Americans to include vegetables, and we're telling them certain ones are bad. White bread and refined bagels are not the best choices every day, that's for sure. However, every once in a while won't kill you."

Good Fat, Bad Fat

Many dieticians maintain that not all fat is bad for the body, and when people avoid it altogether, they avoid healthy foods that provide valuable nutrients.

"While a diet low in saturated fat is a major way to combat heart disease, a diet low in omega-3 fats, which are found in seafood, walnuts, and leafy green veggies, and monounsaturated fats could be counterproductive," says Ward.

Added Ward: "Fat helps you feel full, and it's key to weight control. That may sound strange, but I think a diet that's at least 30 percent fat, nearly all unsaturated, is the best way to manage your weight. "

Even with all of the low-fat foods on the market today, experts say sticking to a diet made up "light" options is not the answer. According to Kimmel, Americans can't ignore the fact that they are getting fatter with those foods because they are simply consuming too many calories.

"Fat free foods still contain calories — and sometimes even more than their fat filled counterparts," adds Kimmel. "Extra calories, even if they come from fat-free cookies or pasta, are still stored as fat. It is ridiculous and impractical to teach someone to avoid anyone one particular food altogether, especially if they enjoy it. Deprivation leads to binge eating."

Moderation Is Key

In the end, experts point to moderate portions of food, and regular exercise as key to losing weight.

"We really need to focus more on helping Americans to moderate on so many levels," says Keith-Thomas Ayoob, spokesperson for the American Dietetic Association and registered dietician at the Albert Einstein College of Medicine.

"That would mean a lot less sugar, from soda and other empty-calorie foods and more fruits, vegetables, whole grains. Moderate would also mean more physical activity," says Ayoob.

Many hope that going back to the basics will overshadow the fad diets and other weight-loss methods that have become so popular in today's culture.

Says Kimmel, "We live in a world where everyone's looking for a quick fix. Diets that encourage moderation of all foods, permanent lifestyle and behavior change and increase physical activity do not carry all of the bells and whistles that most popular diets do. The bottom line is moderation of all foods. If I could bottle that up and sell it, I'd be a billionaire."

Contributing to this report was ABCNEWS' John McKenzie.