My diet is naturally high in fiber. By naturally, I mean that my daily plate is plant based and contains many vegetables and whole grains, foods that are high in both soluble and insoluble fibers. I started increasing my fiber intake after learning from nutritionist/researcher Barbara Rolls, PhD that one could have a full plate of food, feel satiated and stay nourished, by choosing foods (and creating meals) low in energy density (~ 2001).
Energy density, the calories per gram of food, has been the subject of many of my past posts and I have a You Tube channel primarily dedicated to demonstrating how to prepare low energy dense meals.
Many foods that are low in energy density are also high in fiber. A body of literature suggests that eating fibrous foods is health promoting and disease preventing. For an overview of these benefits and the studies that support them, see the Dietary Guidelines for Americans, and the Nutrition Source at Harvard’s School of Public Health.
One of the benefits associated with diets high in fiber is weight control. It makes sense that a diet high in fiber would lead us to eat less if we feel full sooner, or with fewer overall calories. I think, based on my personal experience, that being able to eat more food per calorie is a main mechanism of effect for weight control (aesthetically, emotionally and digestively, we are more satisfied with a fuller plate). Experimental studies show that certain digestive actions, including the release of certain hormones, are what cause a person to feel full and eat less (see e.g., Pereira and Ludwig, 2001). A recent study on mice found that hormones are not just acting in the gut, but in the brain as well. The study: Frost, G., Sleeth, M. L., Sahuri-Arisoylu, M., Lizarbe, B., Cerdan, S., Brody, L., & Bell, J. D. (2014). The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nature Communications, 5, can be viewed for free here.
In the Frost et al study, researchers fed some mice a high fiber diet while feeding other mice normally. The mice on the higher fiber diet did end up weighing less than the other mice (on average). A scientist who did not participate in this study, but who also does this kind of work was interviewed by blogger/reporter Brian Owens. He, the other scientist, made some interesting comments that I wanted to share with you. To paraphrase William Colmers (in Brian Owens article), in order for the researchers to track the fiber and its metabolites through the mice bodies, the mice were fed a lot of fiber. Dr. Colmers said that it is possible that the appetite regulation seen in the lab study was not a chemical reaction in the brain - but a consequence of the mice feeling “uncomfortable.” Dr. Colmers also pointed out that the lab was likely filled with “mouse farts.” I will let you consider the same scenario for a lab experiment with people.
In fact, the next step is to do a fiber feed in human volunteers, but in order to get the level high enough, they will probably be given some form of fiber in a pill. I understand that as a first step, it makes sense to see what is happening by using something artificial or modified, but what we really want to know is what happens when people eat foods that are high in fiber. I don’t know how a study using an extracted form of fiber is going to answer that question.
Here is a link to the piece Brian Owens wrote for Nature.