Dietary Fiber

carrots, apples and radishes

Everyone knows that fiber is a necessary component of any healthy diet, especially Americans. What people in our great nation do not so widely realize is that Americans arguably have the lowest dietary fiber intake in the world, even less than those under privileged members of third world nations. These people, though underprivileged and uneducated in proper dietary behavior are less predisposed to low fiber related cancers, metabolic disorders, heart, and cardiovascular diseases than Americans.

It seems ironic that those most educated in proper dietary behavior, and in the midst of abundant dietary fiber resources, fail so miserably in their food selections. For the most part, Americans know exactly which foods are good for them and which foods are not. Yet we continue to make what seems to be all the wrong food choices. As fitness professionals, and not dieticians, you are still in a position to exert great influence over your clients’ and members’ eating habits. Being an NFPT Certified Affiliate with a complete “Master Food List” in the rear of your NFPT Reference Manual, you will find the fiber content in the foods listed. Provide a copy of this list, as well as a brief education on dietary fiber, to your clients as an important first step to helping them avoid the aforementioned low fiber related cancers, metabolic disorders, heart, and cardiovascular diseases.

The purpose of this article is to educate you in the importance of dietary fiber intake, the differences between soluble and insoluble fiber, and fiber’s fundamental life prolonging functions in the body. None of these are complicated issues, with fiber functions being fairly straight forward. The knowledge gained from this article needs to be conveyed to your clients in an effort to fully convince him/her to pay more attention when making carbohydrate food choices in light of the probable consequences.

Importance of Dietary Fiber Intake…
Fiber is either partially are totally insoluble. This means that not all of a fiber rich food is digestible. That portion of fiber that is digestible works to regulate the release of Insulin which results in a steady energy balance guarding against Diabetes, Hypoglycemia, and other bloodsugar related metabolic disorders. That portion of fiber that is not digestible remains in the digestive tract helping to regulate the processing, movement, and excretion of wastes that are of no use to the body to include toxins, bacteria, carcinogens, etc.. In the absence of fiber the above mentioned toxins remain in digestion longer and are more likely to be absorbed into the body. While there are a host of causes for irregularity in waste excretion, low fiber intake likely tops the list. A great first step in leading your clients to a healthier life-style is accomplished in your initial consultation. Question the client as to his/her past eating behavior. Ask them how many meals they eat per day, ask about mood swings, changes in energy levels throughout the day, what types of foods they eat on a regular basis, meal planning, regularity in bowl movements, etc.. These types of questions will go a long way to pinpointing low dietary fiber problems, and a follow up education on the value, sources, and functions of fiber will be of considerable importance.

Soluble Fiber…
Soluble fiber is abundantly present in almost all natural carbohydrate foods. Foods like fruits, vegetables, beans, etc., are all excellent examples of soluble fiber sources. Without soluble fiber, foods enter into the bloodstream too quickly and are converted into the simple sugar, glucose. This extreme influx in bloodglucose levels overstimulates the Pancreas to produce the hormone Insulin. Insulin’s job is to indiscriminately remove excess glucose from the bloodstream in any way it can. Insulin actually ‘picks up’ circulating glucose and takes it to either the muscles, liver, or adipose tissue (fat cells). If too much Insulin is present, as is the case where low soluble fiber intake is concerned, Insulin’s overreaction reduces bloodglucose significantly and extremely low energy levels result, and given that muscle and liver stores are already full, Insulin carries it’s attached glucose directly to fat cells. When a sufficient amount of soluble fiber is ingested as a component of each meal, digestion acts on foods more slowly and this slower sugar absorption rate into the blood results in a consequent reduction in Insulin release. Less Insulin means higher post-release glucose presence and a smaller fluctuation in bloodsugar. People who have made a lifelong habit of eating more soluble fiber foods, in reduced quantities, more frequently throughout the day, are not as predisposed to related metabolic disorders, they have higher and more balanced energy levels, and with some exception have a healthier body composition.

The Value of Insoluble Fiber Intake…
The value of consuming insoluble fiber is far less complex, and requires much less understanding. Simply put, instruct your clients to pay more attention to food labels while shopping. Instruct them to look for foods with the component ‘BRAN’ on the food labels of supposedly ‘high fiber’ foods. One or two servings of foods with BRAN fiber each day should provide the necessary amount of insoluble fiber for good health. The function of BRAN fiber is simple. Since BRAN is totally indigestible, it moves from the small intestine (where almost all digestion occurs), and absorbing and moving wastes and unusable food stuffs through the digestive tract more effectively and expeditiously. This function of insoluble fiber promotes regularity and it’s presence is crucial if toxins, bacteria, carcinogens, etc., are prohibited from being absorbed.

Once again you are not a registered dietician. However, the above education can and should be passed on to your clients.


These resources are for the purpose of personal trainer growth and development through Continuing Education which advances the knowledge of fitness professionals. This article is written for NFPT Certified Personal Trainers to receive Continuing Education Credit (CEC). Please contact NFPT at 800.729.6378 or [email protected] with questions or for more information.