How Fiber Works
A few years ago, it was the f-word that no one wanted to use. Today, it's plastered all over packages at the supermarket. (That's fiber, people, fiber.) Last year, manufacturers introduced more than 1,500 high-fiber, whole-grain products — an increase of 121 percent since 2005. Now we have high-fiber English muffins and even whole-bean chocolate bars.
Nutritionists' early attempts to get Americans to embrace fiber flopped. But since then, the f-stuff has gotten some serious science behind it. Studies peg foods rich in fiber to a reduced risk of heart disease, diabetes, and cancer — and to losing weight without feeling hungry. For instance, researchers at Harvard Medical School found that women who increased their intake of high-fiber or whole-grain foods over a 12-year period were half as likely to become obese as those who decreased their consumption.
So How Does Fiber Work, Anyway?
Basically, it's the part of plant foods — vegetables, fruits, beans, nuts, legumes, and seeds — that your body can't digest. There are two types of fiber: insoluble, which helps food pass through your digestive system, and soluble, which helps eliminate fat and lower cholesterol. Thanks to soluble fiber, sugars and fats enter your bloodstream at a slower rate, giving you a steady supply of energy. "When you eat foods that lack fiber, your blood sugar can spike quickly. Then it crashes, causing hunger and overeating," says Tanya Zuckerbrot, RD, author of The F-Factor Diet.
The more fiber a food has, the better. "Fiber-packed products tend to be low-cal, so you can eat a lot," Zuckerbrot says. "Fiber makes you full, because it swells in your stomach when it absorbs liquid."
Fiber is also a heart hero: It helps to lower cholesterol and blood pressure, and it increases blood flow. Soluble fiber's effect on cholesterol is so potent that the FDA allows companies to advertise this fact on products like oatmeal. The nutrient may also reduce levels of C-reactive protein (CRP), a marker for inflammation, which has been linked to cardiovascular disease, diabetes, and cancer. Researchers at the University of Massachusetts Medical School in Worcester found that people with the highest fiber intake were 63 percent less likely to have elevated levels of CRP than people who followed lower-fiber diets.
Why You Need More Fiber
Most of us aren't getting enough. The average American woman consumes about 10 to 15 grams of fiber a day — about half of what's needed to meet the basic recommendation of 25 grams. And experts say that more is even better — about 30 to 40 grams a day, according to David L. Katz, MD, MPH, an associate professor adjunct of public health and director of the Prevention Research Center at Yale University School of Medicine. Check out the chart below to learn how to fight hunger and up your intake without upsetting your system.
The 7-Day No-Hunger Diet
Whether your goal is to slim down or to stay healthy, eating more fiber is crucial. If your diet is low in fiber (meaning you don't eat a lot of fruits, veggies, beans, nuts, and whole grains), start by adding one or two of the options below each day, says Martha Gooldy Garcia, RD, a dietitian in Fort Collins, Colorado, who developed this eating plan for FITNESS. If you experience any unpleasant side effects, such as gas or bloating, let your body adjust before adding more. "Be sure to drink plenty of water and stay active," suggests Garcia.
|Day 1||Eat a bowl of high-fiber cereal.||Add fruit, such as kiwi, cherries or dried figs, to your salad.||Munch on popcorn instead of potato chips.||Toss sliced peppers and diced broccoli into your spaghetti sauce.|
|Day 2||Make toast with whole-grain bread instead of white.||Swap your taco for a bean burrito.||Whip up trail mix using high-fiber cereal, nuts and dried fruit.||Put the peeler away: Mashed potatoes taste great with the skins on.|
|Day 3||Have a blueberry bran muffin instead of a bagel.||Eat brown rice with your Chinese takeout.||Dip baby carrots and snap peas in hummus.||Use barley to make “pasta” salad.|
|Day 4||Make oatmeal with cinnamon, raisins, brown sugar and skim milk.||Try a wrap with a whole wheat tortilla instead of your usual sandwich.||Order a fresh or frozen fruit smoothie.||Stir canned pumpkin into your favorite vegetable stew recipe.|
|Day 5||Toss a handful of blueberries onto your cereal.||Put black beans or chickpeas in your salad.||Dip soy chips into low-fat bean dip.||Make soup. Cook broccoli in chicken broth until tender, and puree.|
|Day 6||Sit down to whole wheat frozen waffles.||Instead of pepperoni pizza, have a whole wheat veggie slice.||Munch on apple slices topped with almond butter.||Serve a stir-fry with soba noodles (they’re made with buckwheat).|
|Day 7||Skip the juice and eat an orange with your morning meal.||Fill up on minestrone, lentil or split-pea soup.||Top whole-grain crackers with salsa.||Instead of rice, try quinoa, a nutty-tasting, high-fiber grain.|
12 Smart Swaps to Try Today
|1 cup apple juice: 0.2g fiber||1 apple: 3.3g fiber|
|1 cup spaghetti: 2.4g fiber||1 cup whole-wheat spaghetti: 6.3g fiber|
|1 cup long-grain white rice: 0.6g fiber||1 cup long-grain brown rice: 3.5g fiber|
|1 cup instant mashed potatoes: 1.7g fiber||1 baked sweet potato with skin: 4.8g fiber|
|1 cup macaroni: 1.8g fiber||1 cup barley: 6g fiber|
|1 cup peeled cucumber: 0.8g fiber||1 medium artichoke: 3g fiber|
|1 cup iceberg lettuce: 0.7g fiber||1 cup romaine lettuce: 1.2g fiber|
|1 slice white bread: 0.6g fiber||1 slice hearty whole-wheat bread: 3g fiber|
|1 ounce potato chips: 1.4g fiber||3 cups air-popped popcorn: 3.5g fiber|
|One 1.55-ounce milk-chocolate bar: 1.5g fiber||One 1.3-ounce whole-bean chocolate bar: 6g fiber|
|1 fig-bar cookie: 0.7g fiber||1 cup raspberries: 8g fiber|
|1 cup orange juice: 0.5g fiber||1 cup filtered coffee: 1.1g fiber|
The Whole (Grain) Truth
Stop! Before you put that healthy-looking loaf of bread in your shopping cart, be sure you know what you're getting, advises FITNESS advisory board member Kathy McManus, RD, director of nutrition at Brigham and Women's Hospital in Boston. Read the label carefully — and check the fiber content. In bread, for instance, look for at least 3 grams of fiber per serving (one brand we like: Nature's Own 12 Grain). Choose cereal with a minimum of 2 grams per 100 calories. Other label buzzwords to watch for:
"Whole," as in "100 percent whole wheat" or "whole-grain oats" Ideally, the first ingredient listed should be a whole grain.
"Excellent source of fiber" This means you're getting at least 5 grams of fiber in every serving, while "good source" means that one serving contains at least 2.5 grams of fiber.
"Graham flour" A type of whole wheat flour. So, yes, it's whole grain. But check the fiber content.
"Whole-grain food" Each serving must contain at least 51 percent whole grains. But, depending on the product, the amount of fiber may still be low. For instance, breads contain more water than cereals do, so even when they're whole-grain, they won't necessarily contain much fiber. Always check the label.
"Made with whole grains" If the grains in question appear far down on the ingredients list, put the product back on the shelf.
"Multigrain" The food is made with more than one type of grain, but not necessarily whole grains. Check the ingredients list and the fiber content.
"100 percent wheat" If it doesn't say "whole," it's refined flour, which means all the fiber and nutrients were stripped away in processing.
"Enriched" This term indicates that some of the vitamins have been added back after processing — but the fiber hasn't. Skip it.
Can You Get Your Fiber in a Pill?
Products that you mix into your food, such as FiberCon or Fibersure, are often recommended by doctors to patients who have chronic digestive disorders. They can also be a good way to make sure you're getting the basic recommendation of 25 grams a day. But it's still important to eat foods rich in fiber, which contain vitamins, minerals, and antioxidants. Doctors think some of the health benefits attributed to fiber may depend on these other substances, says Kathy McManus, RD.
Originally published in FITNESS magazine, October 2007.