How Fiber Helps You Lose Weight – It Gets a Little Gross
Fiber is a nutrient. An interesting nutrient! On the one hand, our bodies are completely incapable of digesting it—the fiber we do ‘digest’ is actually digested by our gut bacteria. On the other hand, fiber is associated with a huge list of positive benefits, from lowered blood fats to reduced belly fat to decreased incidence of colon cancer.
To better understand the important role fiber plays not only in weight maintenance and weight loss, but in health in general, here’s a quick overview.
Two Types of Fiber:
1. Soluble Fiber, which can dissolve in water
2. Insoluble Fiber, which cannot dissolve in water
Soluble fibers tend to gel, dramatically increasing blood thickness/viscosity. When we consume soluble fiber, it gels in the stomach, making the chyme (the liquidy digested food that passes from the stomach to the small intestine) thicken. If you imagine how much slower honey drains from a bottle compared to water, then you can see how soluble fiber slows down the rate of your stomach emptying!
Insoluble fibers, on the other hand, absorb less water, do not gel, and do not greatly affect how fast food empties from your stomach. In contrast to soluble fiber, insoluble fiber makes food travel faster through your intestines by adding bulk to it—in this way, insoluble fiber is great in helping to prevent constipation. Since insoluble fiber gains so much bulk, it too can make you feel fuller.
In terms of health benefits, soluble fiber is the one which is most frequently cited. A meal high in soluble fiber moves much more slowly through the digestive tract, which increases fullness.
And it is one of the “magical” reasons why my 30 Days To Lean members cite rarely being hungry.
Another great benefit of soluble fiber is that it makes it challenging for the carbohydrates consumed in your meal to make their way to the lining of your small intestine. As opposed to a thin, liquidy chyme, carbohydrates (specifically glucose, the simple sugar we digest most carbohydrates into) have trouble moving through the thick chyme of a soluble fiber-laden meal.
Ultimately, this means that less carbohydrates are absorbed, and the ones that are absorbed are absorbed over a much greater period of time as opposed to the rapid absorption simple carbs have. The benefits of this slower rate of absorption are two-fold: you have much more prolonged energy, due to the “trickle release” of glucose into your blood, and blood sugar never spikes which means there is no insulin spike and associated “sugar crash”.
In addition to slowing down carbohydrate absorption, soluble fiber can also ‘bind’ fats and cholesterol. Instead of just making it difficult for fat or cholesterol to ‘swim’ to the intestinal membrane, soluble fiber literally locks some of the fat and cholesterol away, completely preventing them from being absorbed.
When we combine the decreased absorption of carbohydrates and the binding of fat in a meal with a high soluble fiber content, what happens is that “total fecal excretion” of calories increases—we poop out more of the calories than we normally would. This sounds gross, but do not say I did not warn you!