Dietary fiber is an indigestible type of carbohydrate made up of sugars linked together into long chains. The indigestible nature of fiber may be the key to its function in the prevention and treatment of a variety of disease states, including high blood lipids and diabetes. Recent research also indicates that fiber may have the ability to help you lose weight.
According to the University of Florida IFAS Extension, fiber supplements may contain ingredients such as wheat dextrin, inulin (chicory root fiber), methylcellulose, hydrolyzed guar gum or psyllium husk fiber. They may come in the form of capsules, tablets, powdered drink mixes, wafers or chews. The Dietary Guidelines for Americans 2010 recommends that adults consume approximately 25 grams of fiber per day. The amount of fiber in different supplements varies by brand.
How Fiber Works
The book "Krause's Food, Nutrition, and Diet Therapy" explains that enzymes in the mouth and the small intestine digest most carbohydrates. These enzymes break them down into smaller carbohydrates and eventually into sugars. From there, the bloodstream absorbs them from the small intestine. Fiber is the exception. Because of the way the sugars link together in fiber, the enzymes in the mouth and intestines can't break it down, so it passes undigested into the large intestine. Fiber may be able to reduce fat absorption by binding dietary fat in the intestine so it passes in the stool.
A randomized controlled trial published in the journal "Molecular Nutrition & Food Research" in 2013 tested the effectiveness of soy fiber biscuits on weight control in 39 overweight and obese college students. Participants ate either a control biscuit or a biscuit containing 27.5 grams of fiber from soy once daily. The fiber group showed a significant reduction in weight, body mass index and LDL cholesterol levels compared to the control group, despite little difference in calorie intake. A second clinical trial from January 2013, published in the journal "Obesity," reported similar results in a larger sample size of men and women. All subjects followed a reduced-calorie diet, and those who consumed the fiber supplement were more likely to lose weight than those who didn't.
Supplements vs. Food
The ability of fiber supplements to promote weight loss begs the question of whether you need to purchase a supplement or can simply increase intake of high-fiber foods. Few high-quality studies have explored the effects of a high-fiber diet on weight loss recently. A 2005 review paper in the journal "Nutrition" reported that the relationship between dietary fiber intake and weight loss was strong though only correlational. Consult with a registered dietitian or a physician to carefully plan your diet to make sure that in the process of increasing dietary fiber you don't also increase calories, which may be counterproductive.