Dietary fiber, remains of the walls of vegetable cells; a complex mixture of hydrates of carbon that it cannot be digested in the intestinal tract and that therefore they are considered lacking of nutritional value. The dietary fiber was discarded during many years by the specialists in human nutrition. However, in the last two decades a surprising appreciation of the importance of the dietary fiber has taken place for the health. With the development of precise methods to measure the different present compounds, today the term non starchy polysaccharide is preferred (NSP) at least precise of dietary fiber.
The diverse types of NSP can be divided in two big groups: those that are insoluble and those that are soluble in water, forming viscous gels. The half diet in the developed countries provides among 11y 12 grams of NSP per day, half of that which comes from vegetable sources and 40% of the cereals. Between the 40 and 50% of the total consumption it is soluble NSP. The biggest consumption in NSP has many beneficial effects; the desirable quantity is about 18 grams per day.

The increased volume of the rich foods in fiber gives them bigger capacity to satiate (that is to say, they make the person to sit down 'full'), what is beneficial to prevent the obesity. And what is more important still: a poor diet in fiber is cause of constipation and compression in the intestinal tract. This has been related with the development of the illness diverticular of the colon, hiatus hernia, hemorrhoids and varicose veins. All these ailments are more common in people than little NSP ingests. The rich diets in fiber are preventive.
These diets also reduce the cholesterol and the risk of cardiac illnesses. The biliary salts are formed in the liver starting from the cholesterol. About 30 grams are segregated a day in the bile. Most of these salts is reabsorbed and recycled. The fiber drags a portion of these salts (and of the same cholesterol that is also segregated in the bile) to be excreted through the grounds instead of being reabsorbed, making that more cholesterol is used to synthesize the salts of the bile.
The same effect also reduces the risk of formation of calculations biliares, since a rich diet in fiber gives more biliary salts and less present cholesterol as a result in the bile. It is the insolubility of the cholesterol when it is in high concentrations in the bile, what causes the formation of biliar stones
The biliary salts have also been related with the development of the cancer of thick intestine. If they mix with the dietary fiber instead of being in free solution, they cannot affect to the intestinal wall to foment the development of tumors.
The dietary fiber has other two important effects in the reduction of the cancer risk. All the diets contain a certain number of having composed potentially carcinogenic (causing of the cancer) that they can no longer be reabsorbed in the body when mixing with the fiber, and therefore they cannot affect to the intestinal cells. Also, the bacteria of the intestine ferment a part of the dietary fiber and it leaves of the products of this bacterial metabolism (especially the butyric sour they have an non grown action that is to say, they help to avoid that they multiply the cells, for what they provide bigger protection in front of the development of the intestine cancer. [1]

MODE OF ACTION OF DIETARY FIBRE IN WEIGHT CONTROL

·                Increased Saliva Production                                                                       

·         Increased Chewing

·         Reduced Energy Intake

·         Increased Gastric Filling

·         Delayed Gastric Emptying

·         Flattening Glucose Absorption

·         Diminished Insulin Secretion

·         Increased Satiation & Satiety

·         Reduced Digestibility

·         Reduced Energy Expenditure

·         Increased Fecal Energy Excretion

Finally, programmes that report lowered drop-out rates may also represent one different form of success. Since after 2-3 years there are few studies that have succeeded in keeping more than 20% - 30% of the original patients in the programme (Brownell & Kramer, 1989), any programme that can document low drop-out rates will constitute one form of success. Even if weight loss may not have occurred, the fact that obese individuals have stayed with the programme means that such a programme is an important tool to develop further and to add qualities to it. The effect  of dietary fibre supplementation, known to be of some help to reduce body weight and maintain that weight loss has been suggested as functioning in this way.