Carbohydrates and Fiber

Dr. Neal Pinckney

Starches and sugars that can be absorbed and used for energy are carbohydrates (Fiber is a form of carbohydrate that does not produce energy). For many years it was mistakenly believed that starches were the cause of weight gain, and as a result many people tried to reduce their weight by reducing their intake of carbohydrates. Food scientists have since learned that we can maintain optimum health and fitness if we increase our carbohydrate intake to 75% or 80% of the calories we eat, and at the same time reduce fats and protein. A simple way to understand the principle behind a comparison of starches, fats and protein is to realize that all carbohydrates have 4 calories per gram, whether sugar or a starch. Fat has over twice that, 9 calories per gram. An 8 ounce baked potato has 1 gram of fat and 25 grams of carbohydrate, giving 110 calories. A 4 ounce lean beef hamburger patty has 24 grams of fat and almost no carbohydrate, giving 350 calories.

The body converts dietary fat into body fat more efficiently than it converts carbohydrates into body fat. Studies show that when the body gets 100 extra calories from fat, only 3 calories are used to convert them, with 97 calories burned for energy or going to storage as fat to be used later for energy. For every extra 100 carbohydrate calories you consume, about 23 will be burned up just in processing them. Only 77 calories will burned or stored as fat. When you eat carbohydrates your chance of storing their calories as fat is more than 20% lower. Even better, since carbohydrates have only four calories a gram, while fat has nine, you can eat over twice the amount of carbohydrate-based food than fat-based food and still get fewer calories.

The body turns almost all carbohydrates into glucose, the primary fuel of the body and the dominant sugar in the blood.

Simple carbohydrates are sugars. It doesn't matter if they come from fruit, vegetables or honey, they all have about the same nutritional and caloric value. These are sometimes called empty calories because (with the exception of black strap molasses) they have little nutritional value. Dietary sugars are broken down into their simplest form, glucose and fructose, and are absorbed into the cells for energy.

Complex carbohydrates are glucose molecules usually combined with fiber, cellulose and starches. They provide more nutritional variety than simple carbohydrates and are a major source of dietary fiber, which is not found in animal products. Soluble fiber is an important factor in lowering blood cholesterol, but it has become an increasingly smaller part of the typical American diet, mostly due to the popularity of white flour, which has very little fiber. Whole wheat flour and other whole grains are rich in fiber and complex carbohydrates. Two slices of whole wheat bread has about 140 calories, while a typical soft drink has about 150. A soft drink is basically sugar (simple carbohydrates) while whole wheat bread is made from mostly complex carbohydrates, dietary fiber, a variety of vitamins, minerals and essential amino acids. While some sugar is not harmful, we can get all of the sugars we need from fruits, vegetables and whole grains.

Carbohydrates are often believed to be fattening , but they are not nearly as responsible for weight gain as fats are. Cakes, pies and baked sweets usually contain more fats than they do sugars. Pasta, rice and beans have about 20 grams of complex carbohydrate per half cup, cooked, and not one gram of sugar. Potatoes, peas and corn have 12 grams of complex carbohydrates per half-cup, and only 3 grams of sugars (simple carbohydrate). Most vegetables are high in fiber, low in sugar, and almost all are rich in complex carbohydrates.

Fiber is essential in reducing the risk of some kinds of cancer, intestinal disease, gallstones, diabetes, obesity and heart disease. Fiber is a carbohydrate that has no calories, as it is not metabolized by the body.

There are two types of fiber:

Sponge-like insoluble fiber, from grains, legumes, fruits and the outer surface of some seeds, promotes food passage and adds bulk, which reduces food craving. Processed grains and foods often have most of their fiber removed. Use whole grains, brown rice and unprocessed foods to assure sufficient fiber intake. Whole wheat bread and brown rice have three times the fiber of white bread and white rice.

Soluble fiber acts as a filter to help prevent some substances, including cholesterol and glucose, from being absorbed into the blood. It also acts as a stool softener, preventing constipation, which is related to colon cancer and diverticulosis. Constipation often leads to straining to clear the bowels, a common precursor of strokes. Eating foods high in fiber may help prevent these problems and reduce cholesterol as well.

Fiber binds to bile acids, which contains cholesterol eliminated by the liver and is excreted if enough fiber is present. Not enough dietary fiber leads to a lack of bile/cholesterol binding, allowing cholesterol to be reabsorbed back into the bloodstream, where it can damage arteries.

Fiber increases the viscosity of intestinal contents and slows down the interaction between starch and enzymes. This slowed digestive process decreases the glycemic index of foods present and reduces the rate and level of blood sugar increase. The reduced blood sugar levels also reduce insulin requirements. Following a high fiber, low glycemic diet can usually eliminate or reduce the need for drugs to manage type 2 diabetes.

Refined and processed fruits and juices may also be low in fiber. Comparing an orange and an 8 ounce glass of reconstituted frozen orange juice, the juice has 0.848 grams of fiber while the orange has 9.790 grams, more than 11 times the fiber in the juice. A fresh orange also has a third fewer calories than a glass of orange juice. A few juices do contain high amounts of fiber; unfiltered carrot juice has about 75% of the fiber of raw carrots, but suprisingly tomato juice can have even more fiber than raw tomatoes.

Most spaghetti noodles and other pastas are made from white flour from processed grains, which have two-thirds of the fiber removed and much of the nutrtritional value missing. To get all the natural fiber and benefits, choose whole-wheat pastas, bulgar wheat and other whole grain products. For maximizing weight loss, eating foods high in fiber is even more essential.

Meat and all other animal products do not contain fiber, no matter how tough and chewy it is.

Recommended fiber intake varies from 25 to 35 grams a day. If one eats a balanced vegetarian diet, with whole grains, legumes and vegetables, it is not usually necessary to take any kind of fiber supplements.