Do diet sodas help you diet? I'm hooked on diet cola. Will it really help me lose the pounds? … and more of your questions answered here

Shape, Nov, 2004 by Suzanne Schlosberg

Q I'm concerned about my addiction to diet soda. I drink at least five cans a day and worry it may be unsafe to consume so much aspartame. How much is too much? Since regular sodas are full of sugar and I'm trying to lose weight, which is the lesser of the two evils?

A There's no reason to worry that the artificial sweetener aspartame will increase your risk for cancer or any other disease, says David Schardt, M.S., a senior nutritionist at the nonprofit Center for Science in the Public Interest, a Washington, D.C.-based watchdog organization. "Some people believe aspartame gives them headaches," Schardt says, but this notion is disputed by most research.

According to the U.S. Food and Drug Administration, the only people who need to avoid aspartame are those with the genetic disease phenylketonuria (PKU), those with advanced liver disease and pregnant women with high levels of phenylalanine in the blood. People in these groups do not effectively metabolize the amino acid phenylalanine, one of aspartame's components, and high levels of this amino acid in body fluids can cause brain damage.

Since regular soda has about 150 calories per 12-ounce serving, diet soda, which contains no calories, is the better option. However, Schardt notes, "there isn't a lot of good evidence that drinking diet soft drinks will help you lose weight." Few published studies on the topic are available, and results have been mixed. But one thing is clear: The United States leads the world in consumption of artificial sweeteners, yet we are the most overweight economically developed nation in the world.

"You'd think, intuitively, that if you substitute a no-calorie soda for one with calories, you'd lose weight," Schardt says. "But many people think, 'If I drink a diet soda now, I can have a special treat later on.' People somehow compensate for the calories."

Q What is the difference between soluble fiber and insoluble fiber? Which is more important for weight loss?

A Soluble and insoluble fiber are found in many of the same foods, and both types are helpful for weight loss. "The main difference is that soluble fibers dissolve in water and insoluble fibers do not," says Leslie Bonci, M.P.H., R.D., director of sports nutrition at the University of Pittsburgh Medical Center.

In practical terms, this means that soluble fiber forms a gel when mixed with the liquids you consume and takes longer than insoluble fiber to empty from the gastrointestinal tract. Soluble fiber lowers cholesterol levels, thereby reducing heart-disease risk; insoluble fiber is the type that helps keep you regular. Rather than dissolving in water, insoluble fiber holds onto water, helping move waste through the body.

Many foods, including fruits and vegetables, contain both types of fiber. Take an apple, for instance: "The flesh is soluble fiber, but the skin is insoluble," Bonci says. Good sources of soluble fiber include oats and oat bran, barley, beans and peas, peanuts, pecans, walnuts, brussels sprouts, carrots, oranges, apples and grapefruit. Among the best sources of insoluble fiber: brown rice, whole-wheat bread, bran cereals, green peppers, cabbage, spinach, cherries, berries and pears.

"More fiber of both types is really what you want," Bonci says. "The recommendation for women is 25 grams of fiber per day, but most people are still getting only around 8-10."

When you eat fiber-rich foods--which tend to be low in calories--your brain has time to register fullness before you've overeaten. (That's why an apple--with 3 grams of fiber--leaves you feeling more satisfied than a 6-ounce glass of apple juice, which has no fiber.) Studies show that people who are provided high-fiber meals and allowed to eat to their heart's content consume about 10 percent fewer calories than people served foods lower in fiber. The effect seems to be greatest with overweight people. A review of several studies found that, when given high-fiber foods, overweight or obese people ate, on average, 18 percent fewer calories than overweight people who ate low-fiber foods.

Q The brand of white bread I buy actually has more fiber than some wheat breads and it tastes a lot better. So is there any point in buying the wheat bread? Isn't fiber content the main reason to eat wheat bread?

A Don't confuse "wheat" bread with "100% whole-wheat" bread, says University of Colorado associate nutrition professor Jackie Berning, Ph.D., R.D.: "There are many 'wheat' breads that are nothing more than white bread that has been caramel-colored." For example, Millbrook's Cracked Wheat Bread, a hearty-sounding brown bread, has no grams of fiber, whereas even plain old white Wonder Bread has 0.5 gram per slice. "Always read the label," Berning advises. "You might think you're getting a whole-wheat product when you're not." The terms cracked wheat, multi-grain and stone-ground wheat don't necessarily mean the product is rich in fiber, either. These breads may use mostly refined white flour with a sprinkling of whole-wheat flour. Even Oroweat 12 Grain Bread contains just 1 gram of fiber per slice.