On the “Today” show’s “Take It Off” series, we’re taking a closer look at carbohydrates — the good, the bad and the ugly. Some diets will have you believe that, when it comes to losing weight, carbs are the enemy. But the fact is, the body needs carbohydrates; it's nature’s preferred source of energy. Madelyn Fernstrom, a “Today” contributor and director of the Weight Management Center at the University of Pittsburgh Medical Center, was invited on the show to explain what carbs we should include in our diets and which ones we should avoid:
Carbohydrates often get a bad rap: they make us fat, they cause diabetes, and they stimulate our appetites. When people think of carbs, they often conjure up images of cake, bread, or pasta. The truth is that carbohydrates are one of the three major nutrients found in our diet, along with protein and fat — and we need them to stay healthy.
Our bodies need carbohydrates for energy. Yet, unlike protein and fat, there is no daily recommended requirement. Carbohydrates are the body’s preferred energy source — whether as a ready source (consumed as a carbohydrate) or a longer-term one (converted from protein and fat). However, we need carbohydrates for energy (it takes too long to convert protein to carbohydrates for quick energy).
Calories are fattening, not carbs. In fact, each carohydrate contains four calories per gram of food — the exact same calories as a gram of protein. Fat, on the other hand, has nine calories per gram. Even though carbohydrates have the same calories as protein, they have different metabolic effects on the body. Protein has a neurochemical effect on the brain to make you feel more satisfied, or fuller, when you eat.
When people lose weight, fat is converted to carbohydrates and used for energy, during the body’s normal metabolic cycles. (This is called the Kreb’s cycle.) Normally, our bodies do not store carbohydrates because we quickly use them. More often, the body converts proteins and fats into carbohydrates, which are then stored as fat.
That’s why if you strictly limit or cut carbohydrates to lose weight, you will feel sluggish and fatigued. People always wonder why when they cut out carbs, they usually feel worse, not better. So to stay healthy, and feel energetic, here’s the lowdown on the carbohydrates you need in your diet, and the ones you need to limit.
Seek out foods containing complex carbohydrates and fiber, like those found in fruits, vegetables and whole grains. There are two kinds of carbohydrates: starchy ones found in potatoes and whole grains, and non-starchy ones found in fruits and vegetables. The basic rule is to focus on fruits and vegetables as your main source of carbohydrates and limit the starchy ones. Keep in mind that you should eat five fruits and vegetables a day.
Fiber helps keep you full, so you won’t need to ingest as many calories to feel satisfied. Fiber also slows the rate that the stomach empties, so you feel fuller longer. Fiber is not a carbohydrate. It is found in whole grain foods, fruits, and vegetables. Fiber is not digested, or absorbed by the body, so it doesn’t have calories.
Fruits and vegetables are high in fiber, low in fat, and contain plenty of water. So they have a low-caloric density (fewer calories per ounce) than other foods, and they make you feel full. Starchy, whole-grain carbohydrates are also rich in fiber, so they make you feel full and help you reduce total food intake. Refined grains, like those found in white bread, won’t give you the same benefits.
There are two kinds of fiber: soluble and insoluble. Soluble fiber is good for healthy hearts, while insoluble ones are good for digestion. Soluble fiber, which dissolves in water, forms a gel when mixed with body fluids, while insoluble fiber isn’t absorbed in the body and is eliminated through the digestive track.
Soluble fiber binds fatty acids (fat) and slows the rate at which food leaves your stomach, so it helps keep you full! When there is food in your stomach, you minimize the physical signs of hunger and prolong your sense of contentment. The best sources of soluble fiber to limit calories: oats, oat bran, fruits, and vegetables.
Insoluble fiber is a bulking agent that moves food through the intestine, absorbing water and promoting regular bowel movements and preventing constipation. Best sources to limit calories: whole wheat products, corn, bran, fruits, vegetables.
Most people don’t get enough fiber in their diet. Aim to eat 20 to 25 grams of fiber a day. If you eat five fruits or vegetables daily and a few servings of whole grain products, you have enough fiber. If you think you need a fiber supplement, check with your doctor first.
Avoid processed carbohydrates. These include grains whose high-fiber shells have been stripped away. Think of white flour or white rice. The calories are the same, but without the fiber, you lose the metabolic satisfaction of eating a grain. Also stay away from carbs that are combined with white sugar (sucrose) and/or fat. White bread, doughnuts, cake, and pasta contain white flour.
Of course, you want to choose products made with whole grains. But to save calories, and reduce your carb intake, you can switch to “light” or “reduced calorie” bread (this just means more air has been whipped into it.) A good example is Country Hearth Light 100% whole wheat bread. Two slices of this thin-sliced bread have the same calories as one slice of 100% whole wheat bread of the same brand.
Avoid low-carb pasta and breads. These products are made with soy flour (protein flour), have a chewy consistency and don’t taste anything like their whole grain counterparts. You’re better consuming smaller amounts of a fiber-rich product, like whole wheat pasta or whole wheat bread. Also many breads and cakes made with protein flour have a lot of added fat — and more calories.
Final thoughts: The food police will not come and arrest you if you eat some white flour products. Just think whole grain when you choose the starchy carbohydrates. Think of a food pyramid where fruits and vegetables are on the bottom, so they’re your main source of carbohydrates.
Limit your eating of starchy carbohydrates. Note that corn and peas are starchy carbohydrates, so they have a higher caloric density (more calories per serving than the other vegetables).
And remember that milk contains carbohydrates: The lactose in milk is sugar, a carb. So for both health and weight control, try to eat carbs that are high in fiber and have a high water content.
Madelyn Fernstrom, Ph.D., is the founder and director of the University of Pittsburgh Medical Center Weight Management Center and associate director of the UPMC Nutrition Center in Pittsburgh. She is also an associate professor of psychiatry, epidemiology and surgery at the University of Pittsburgh School of Medicine, and a board certified Nutrition Specialist (American College of Nutrition). For more than 25 years, she has studied and treated obesity and eating disorders. And she is the author of “The Runner's Diet” published in the fall of 2005.