Fiber is Your Friend
Mmmm, fiber! Maybe you’ve seen the television ads: a legion of short-sleeved, skinny nutrition nerds circulating through the community with their cereal boxes, earnestly trying to get you excited about eating your fiber!
If your macronutrients had roles in a TV drama, protein would surely be the noble hero and fat the tempting villain, with carbohydrate as the complex, misunderstood protagonist, ever struggling to find balance. And then there would be fiber, the dorky sidekick, the essential second banana, the butt of the jokes.
Strictly speaking, fiber really isn’t much of a nutrient. Dietary fibers are strings of sugar molecules, but the links between the molecules can’t be broken down by our digestive enzymes, so these sugars pass through our bodies without being metabolized. It provides bulk, but few or no calories.
Because of this, fiber can be a great friend to people trying to lose weight or gradually make the change to healthier eating habits. A massive study by Tufts University showed that when people consciously chose to consume more fiber, they reduced their overall caloric intake by about 18 percent and hence, lost weight—even if they didn’t deliberately cut back on other foods.
The researchers said that’s probably because of specific characteristics of high-fiber foods. To begin, high fiber foods, like vegetables and whole grains, are generally low-calorie to begin with. They also take more time to chew, giving the body a better to chance to recognize that it’s been fed—before it’s been overfed!
High-fiber foods also stay in the stomach longer, and that keeps the feeling of fullness and satisfaction around, delaying the return of hunger and another round of eating.
There are two kinds of fiber found in fruits, vegetables and grains—soluble and insoluble fiber.
Soluble fiber dissolves in water, forming a thick, jelly-like substance. Soluble fiber is longer lasting than insoluble fiber, so it stays in the stomach longer and helps to decrease hunger. It is also helps lower cholesterol, control blood sugar, decrease carbohydrate absorption, and bind to fat from our foods and pull it from our system.
Fruits that contain soluble fiber include apples, pears, oranges, grapefruit, and figs. Among the vegetables containing soluble fiber are beets, okra, carrots, and dried beans. Oatmeal and legumes (dried beans, peas, and lentils) are other good sources. More exotic sources of soluble fiber are carob seeds and seaweed.
The thickening property of soluble fiber is apparent in the jams and jellies we eat. Pectin is a soluble fiber that comes from the pulp of soft fruits and some vegetables; it is the stuff that makes jellies gel.
Soluble fiber changes very little as it passes through the body. Acting mainly as a sponge, it absorbs many times its weight in water. Fiber that has absorbed water adds bulk to the stool, which generally causes it to move through the intestines faster. Because of this, it may prevent diverticulosis and constipation.
Insoluble fiber is abundant in unrefined cereals, whole-grain flours, fruits and vegetables. Fruits that are rich sources of insoluble fiber include berries, prunes, bananas, cherries, plums, apples and pears. Vegetables containing insoluble fiber include cauliflower, onions, broccoli, mushrooms, spinach, potatoes, carrots and beans.
People are a little more aware of fiber today than they were in our parents’ generation. It really wasn’t until about the 1960s that fiber began to come into its own as the essential companion to fats, protein and carbohydrates.
British researchers working in Africa around that time noted that Africans had a much lower incidence rate for certain diseases, heart disease and diabetes in particular, compared to folks in Western cultures. They figured the Africans’ high-fiber diet had something to do with it, as most native Africans eat large quantities of unprocessed plant foods and very little fat or animal protein.
They were right. Since then, numerous controlled studies have borne the concept out, and scientists can now track the relationship between higher fiber intake and reduced incidence of the same diseases in the U.S. population.
Fiber and health
Researchers looked at how high-fiber and low-fiber cereals affected the post-prandial insulin — the level after eating — of people who have both normal and high insulin levels at baseline.
Even for people who typically have high insulin levels, the fiber-rich cereals created more gradual adjustments to blood sugar and insulin levels, whereas the low-fiber cereal caused the sharp fluctuations that are the reason behind miserable hunger symptoms.
To avoid such misery, Dr. Cederquist recommends that her patients eat a breakfast that’s high in fiber or low-fat protein. Either choice keeps insulin levels and blood sugar in check, while the typical low-fiber choices of processed cereal, bagels or, worst of all — donuts! — will only leave them starving again by 10 AM.
Not only does fiber speed up the journey of food through the intestines because of the bulk it adds, but people on high fiber diets also have stronger colon muscles. These muscles push the food along more rapidly than do the weak colon muscles of people who eat mostly soft foods.
By eating foods high in fiber, you can be assured of more frequent, and easier, bowel movements. Dietary fiber is highly recommended as the safest and most effective way to prevent constipation.
Evidence also suggests that high fiber diet can protect against heart disease and strokes. Research findings show that people who eat significant amounts of soluble fiber have low levels of the type of blood cholesterol that’s associated with these conditions. Insoluble fiber, while beneficial in other ways, doesn’t have this effect.
People with diabetes have problems controlling their levels of blood glucose — the sugar found in the bloodstream. Research indicates that soluble fiber in the diet may improve this control, often reducing the insulin requirements of diabetic patients.
How does this happen? Scientists believe that some fibers may delay the digestive process enough that sugar is released into the bloodstream more slowly. Such slow release allows the body to handle the sugar as it becomes available. The positive effect of fiber is more pronounced in people with adult-onset diabetes than in those who have had the disease since childhood. Other factors may be at work as well. Diets high in fiber are usually high in vegetable starches. Foods containing these starches promote stable levels of blood glucose, while sugary foods cause rapid changes as glucose levels go up and down. For this reason, many physicians advise that their diabetic patients increase the amount of fiber in their diets.
THROUGH THICK & THIN:
Good research shows that if you simply add more fiber to your diet, you’ll probably lose weight, even if you’re not trying. Most Americans should double the amount of fiber they eat, and if you really want a quick healthy and weight benefit, try cutting some of those empty junk-food calories and replacing them with good low-calorie fiber sources.