Being overweight is associated with heart disease, some types of cancers, type 2 diabetes (noninsulin-dependent), stroke, arthritis, breathing problems, and depression. A diet high in fiber can help you control certain medical conditions by helping you control your weight, but fiber can also benefit you as it travels through your digestive system. Dietary fiber is the part of whole grains, vegetables, fruits, and nuts that resists digestion in the stomach and intestines and, depending on the type of fiber ingested, can help to control certain health conditions.

How does fiber help you lose weight?
Fiber alone contains no calories, and it provides the bulk to your diet that gives you the satisfaction of chewing, plus the feeling of a full stomach. There are 2 types of fiber: water-insoluble and water-soluble. Water-insoluble fiber, found in vegetables and whole grain breads and cereals, adds bulk to the diet. Water-soluble fiber, found in fruits, legumes, seeds, and oat products, exits the stomach more slowly and helps your stomach feel full longer. Fiber has several additional benefits that can help you to control your weight. For example, foods containing fiber take longer to eat, which means your stomach feels full sooner and you eat less. Foods with fiber are also satisfying so you don't feel hungry between meals.

What are the other benefits of a high fiber diet?
A high fiber diet and weight loss (through reduced calorie intake and exercise) can reduce your risk of certain medical conditions. The type of fiber you digest determines your benefits. For example, a diet consisting of insoluble fibers may reduce your risk of colon cancer. Insoluble fiber passes through the body quickly carrying cancer-causing substances through the digestive tract quicker. Additionally, insoluble fiber helps to prevent or relieve constipation because it exits the body quickly. On the other hand, a diet rich in soluble fiber can help to reduce your risk of stroke, control diabetes, prevent some cancers, and avoid gastrointestinal disorders. Soluble fiber can also help lower your blood cholesterol and lower your risk of cardiovascular (heart) disease. Soluble fiber absorbs fluids as it moves through your digestive track. During the process, the fiber dissolves, thickens, and forms a gel. This gel binds itself with acids made from cholesterol from the liver and then carries it out of your body through your waste. Your body is left to pull the cholesterol from your blood stream, reducing your blood cholesterol. The gel moves slowly through the digestive system. It slows the release of sugar and slows sugar absorption, thereby moderating blood glucose levels. The gel also creates softer and bigger stools, which means fewer hemorrhoids and fewer bouts with constipation.

Adding fiber to your diet
The National Cancer Institute recommends a daily intake of 20 to 35 grams of fiber. However, most Americans only eat between 10 to 15 grams of fiber per day. A floating stool and easy passage indicates that your diet has enough fiber. Do not consume fiber until it causes many loose stools a day because important nutrients can be lost and vitamin deficiencies can occur.

Fiber is not the cure all for weight control. However, combined with a nutritious diet, fiber can help you lose weight. You should begin by adding fiber slowly to your diet to avoid bloating and gas. In addition, drink plenty of fluids. Eight glasses of liquid are recommended a day because fibrous foods draw water from the intestines. Eat a variety of high-fiber foods to receive the benefits from both the water-insoluble foods and the water-soluble foods, including raw vegetables and fruits with the skins. When possible, consume high-fiber carbohydrates such as an apple instead of low-fiber carbohydrates found in apple juice.

Shopping for fiber
Shopping for good, nutritional foods is an important part of adding fiber to your diet. Keep a shopping list and only buy what you need. Also, do not shop on an empty stomach. Studies indicate that hungry shoppers are less discriminating and buy more junk food.

• Shop for fresh produce twice a week. Many vegetables lose their nutrients during prolonged refrigeration.
• Avoid wilted vegetables and bruised fruits.
• Choose small, young vegetables.
• Select whole grain products for greater nutritional content instead of "enriched" breads.
• Visit larger stores or health food stores for whole-grain flours and hard-to-find nuts and seeds.

Jan McBarron, MD
Columbus, GA