It is well known that fiber has appetite-suppressing properties. In fact, Brenda and I wrote an entire book about it—The Fiber35 Diet. Fiber works in a number of ways to suppress appetite. Fiber expands in the stomach, taking up more space, which makes you feel full. In addition, fiber slows the emptying of food from the stomach into the intestines, which promotes satiation. Fiber also triggers the release of the hormone cholecystokinin (CCK) which sends messages to the brain that the stomach is full.

In a recent study published in the journal Nature Communications, an international team of researchers identified another way in which fiber reduces appetite.¹ It has to do with your gut bacteria. They found that when fermentable carbohydrates (soluble fiber, in particular) are converted into acetate (a short-chain fatty acid produced when gut bacteria ferment the fiber), appetite is curbed. “Our research has shown that the release of acetate is central to how fiber suppresses our appetite and this could help scientists to tackle overeating,” noted Gary Frost, PhD, lead researcher.

Using an animal model, they first tested the ability of inulin—a soluble fiber known to have prebiotic effects—to promote weight loss when compared to cellulose, an insoluble fiber that is not fermented by gut bacteria. Inulin did lead to weight loss, which was not surprising because it has been found to do so in a number of animal and human studies. Next, they tracked the production of acetate in the gut as a result of colonic fermentation of inulin. They found that from the colon, acetate entered systemic circulation and concentrated in the liver, heart, and the brain. In the brain, it concentrated in the hypothalamus, an area of the brain that controls hunger.

“From this we could clearly see that the acetate accumulates in the hypothalamus after fiber has been digested. The acetate then triggers a series of chemical events in the hypothalamus leading to the firing of pro-opiomelanocortn (POMPC) neurons, which are known to suppress appetite,” stated Sebastian Cerdan, PhD, one of the researchers.

To confirm that it was acetate, and not another compound, that contributed to weight loss, they administered acetate directly and found that it reduced food intake and led to a number of changes that trigger appetite suppression. “It’s exciting that we have started to really understand what lies behind fiber’s natural ability to suppress our appetite and identified acetate as essential to the process. In the context of the growing rates of obesity in western countries, the findings of the research could inform potential methods to prevent weight gain,” noted Jimmy Bell, PhD, another of the study’s authors.

I think this finding of satiety when consuming fiber points back to the natural order of things. By most all accounts, ancient man—as well as modern man—living in jungles and rural agrarian communities (outside of USA and Western countries in general) consume 60 to 80 grams of fiber daily. Acetate levels in these populations are high which promotes satiety and majorly balances immunity.²

Could it be we were meant to eat a high-fiber, plant-based diet to live a satisfied, disease-free life? Could it be that once again man’s ego has run amok by creating processed simple carbs, fake foods and sugars, which has jeopardized the future of the human race? I also think the best way to get acetate is via eating high-fiber foods that promote acetate production in the gut rather than just taking acetate. It is time for change and we can do it only one at a time with our purchasing power and example. Support organic foods and local whenever possible.

References

1. Frost G, Sleeth ML, Sahuri-Arisoylu M, et al., “The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism.” Nat Commun. 2014 Apr 29;5:3611.
2. Fukuda S, Toh H, Hase K, et al., “Bifidobacteria can protect from enteropathogenic infection through production of acetate.” Nature. 2011 Jan 27;469(7331):543-7.