Anti-Appetite Molecule in Fiber that Impacts the Brain Could Combat Obesity

Want to suppress your appetite? Then eat more fiber. But why exactly does fiber help keeping you from going hungry? Scientists may have just discovered the reasons why.

Dietary fiber is found in most plants and vegetables. Yet it tends to be at low levels in processed food. When fiber is digested by bacteria in our colon, it actually ferments and releases large amounts of acetate as a waste product.

In order to better understand how dietary fiber suppresses appetite, the researchers tracked the pathway of acetate from the colon to the brain and identified some of the mechanisms that allow it to influence appetite. More specifically, the scientists analyzed the effects of dietary fiber called inulin, which comes from chicory and sugar beets and is also added to cereal bars.

Using position emission tomography (PET) scans, the researchers tracked the acetate through the body from the colon to the liver and the heart. Eventually, it wound up in the hypothalamus region of the brain, which controls hunger. They then investigated the effects of acetate on the hypothalamus and found that it accumulates after fiber has been digested. The acetate then triggers a series of chemical events in the brain, which leads to the firing of pro-opiomelanocortin (PMPC) neurons, which are known to suppress appetite.

"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," said Jimmy Bell, one of the researchers, in a news release. "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."

The findings could allow researchers to develop new ways to suppress appetite using acetate. That said, they'll have to discover a way to have it mimic the slow release it has in the gut.

"It's becoming increasingly clear that the interaction between the gut and the brain plays a key role in controlling how much food we eat," said David Lomas, one of the researchers, in a news release. "Being able to influence this relationship, for example using acetate to suppress appetite, may in the future lead to new, non-surgical treatments for obesity."

The findings are published in the journal Nature Communications.