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Learn how this nutrient should fit into your nutrition plan.
Fiber (also known as roughage) is the name given to two kinds of highly complex carbohydrate that are totally indigestible. Although fiber is technically carbohydrate, unlike other forms of carbohydrate (sugars and starches) it provides no calories because it is not absorbed into the bloodstream. Insoluble fiber (mainly cellulose) is an important structural material in plants. It does not provide nutrition to humans when consumed but instead benefits us by absorbing and neutralizing toxins and by contributing to well-hydrated, bulky solid waste that is easily passed. Water-soluble fiber helps the body absorb minerals and helps remove nutrient excesses, including cholesterol, from the body.
Fiber and Health
Adequate fiber intake is essential for optimal health, while inadequate fiber intake is associated with a variety of diseases and health conditions. Specifically, a high-fiber diet is known to reduce the risk of obesity, Type 2 diabetes, cardiovascular disease, and constipation. One of the reasons these diseases and conditions are so prevalent in our society is that we do not consume enough dietary fiber. The U.S. Surgeon General and many professional health organizations recommend a diet providing 20 to 35 grams of fiber a day. The average American consumes a scant 10 to 15 grams daily.
Fiber and Body Weight
Excess body fat is the primary cause of cardiovascular disease and Type 2 diabetes. A high-fiber diet may reduce the risk of cardiovascular disease and Type 2 diabetes by reducing body fat storage. Fiber slows digestion so we feel fuller longer and consequently eat less. Therefore, getting enough fiber in your endurance sports nutrition diet is very beneficial when it comes to achieving the lean body composition that will lead to optimal training and racing performance.
Fiber and Foods vs. Supplements
While natural foods such as fruits, vegetables, and whole grains are the best sources of dietary fiber, fiber supplements can be a good backup source. If you are currently getting less than 35 grams of fiber daily and you’re finding it difficult to add more whole grains, beans, fruits, or vegetables to your diet, use a fiber supplement such as Metamucil or Benefiber. Use it according to label directions and aim for a total of roughly 35 grams of fiber daily from food and supplement sources combined.
Here’s a list of high-fiber foods:
Apple – 4.4 g per apple
Broccoli – 5.1 g per 1 cup
Brown rice – 3.5 g per 1 cup (cooked)
Lentil beans – 16.2 g per 1 cup (cooked)
Peas – 8.8 g per 1 cup
Pear – 5.5 g per pear
Raspberries – 8.0 g per 1 cup
Whole-wheat bread – 1.9 g per slice
Whole-wheat spaghetti – 6.2 g per 1 cup
Fiber and Your Running Nutrition Plan
While fiber is unquestionably a good thing that most of us don’t get enough of, poorly timed fiber intake can have unfortunate consequences for the endurance athlete. That’s because fiber slows the emptying of food from the stomach. So consuming too much fiber too soon before, say, a half-marathon training run or triathlon training ride may cause your stomach to be upset. Therefore, if your last meal before a workout is fiber-rich, be sure to allow at least two hours for it to digest. And if your last meal or snack before a workout is consumed only an hour out, be sure to make it low in fiber content.
Increasing your fiber intake is likely to change your bathroom habits slightly. Specifically, it will make them more regular, which is a good thing. But there’s a chance that, in doing so, it may require you to adjust your meal and/or workout schedule a bit so you don’t find yourself having to interrupt your 10K training speed work session or long marathon training run with annoying pit stops.