The human brain is a marvel of evolution, but in matters of the gut, it’s taking cues from a much more lowly source.

When we eat, what we’re really doing is feeding the microbes in our digestive system. They in turn signal the brain when they’ve had enough to tell it we’re full, according to a new study out of the University of Rouen in France.

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“We now think bacteria physiologically participate in appetite regulation immediately after nutrient provision by multiplying and stimulating the release of satiety hormones from the gut,” says lead researcher Dr. Serguei Fetissov.

The study, published in the journal Cell Metabolism, focused on Escherichia coli (E. coli), normally present in the guts of mammals and birds. Although some strains of E. coli can be harmful, they also keep out other kinds of harmful bacteria.

Fetissov and his team found that after E. coli has been digesting food and multiplying for 20 minutes, they start producing certain proteins. According to the scientists, it’s no coincidence that this is the same timeframe it takes for someone to start feeling full after a meal.

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When the French researchers injected small doses of the bacterial proteins released once the bacteria had begun eating, the animals would eat less, regardless of whether they were hungry or well fed. Those proteins also stimulated the release of two kinds of peptides: one that suppresses appetite, and another that prompts the body to produce insulin.

“Our study shows that bacterial proteins from E. coli can be involved in the same molecular pathways that are used by the body to signal satiety,” Fetissov sums up, “and now we need to know how an altered gut microbiome can affect this physiology.”