It’s a bacteria’s world and we’re just living in it. A new study has found it’s not our stomachs that are responsible for letting our brains know whether we're hungry or not, but rather the E.coli bacteria living in our gut. The research has now opened up new discussions regarding how we can control hunger and prevent overeating.

In a recent study published in Cell Metabolism, a team of researchers investigated the biological mechanisms that control hunger. Other research, meanwhile, has revealed that the composition of our gut microbiota has a large influence over our eating habits and digestion. However, it has not been revealed whether these bacteria have any influence over appetite specifically.

For their study, the team showed bacterial proteins produced by E.coli could suppress the appetites of rats and mice when injected into them. This suggests these bacteria have an influence on the release of gut-brain signals and the activation of appetite-regulated neurons in the brains of humans, Medical Xpress reported.

After we eat, bacteria in our guts break down the nutrients and subsequently divide in order to replace any bacteria lost in the production of feces. However, about 20 minutes after the mice ate, the researchers observed their gut bacteria producing different proteins that it had at the beginning of the digestion process. It's these proteins that seemed to stimulate the release of satiety hormones from the gut, the report said.

It's only natural that the parasitic bacteria would develop a way to communicate with their host when they're full. Without the means to gather their own food, gut bacteria’s only source of nutrients is to ingest its human host’s last meal.

According to lead researcher Sergueï Fetissov, now that we know the influence gut bacteria has on our appetite, it’s important to understand how an altered gut bacteria population affects this process. Past research has shown that disrupted gut bacteria can cause an overproduction of Firmicutes, a class of bacteria known for breaking down fiber and absorbing dietary fat. This overproduction in turn means gut microbes could the body to retain weight without the host needing to actually eat any additional food.

High levels of fat and sugar found in the modern Western diet may also interfere with gut bacteria, and render the brain unable to prevent overeating. In mice studies, for example, high fat diets have also been linked to gut microbe changes, which led to "increased intestinal permeability and markers of inflammation," hallmarks of weight gain and depression.

Although it’s unlikely that doctors will begin injecting patients with gut bacteria in an effort to control appetite and combat obesity, understanding where exactly our relationship with food goes wrong is the first step toward correcting it.

Source: Fetissov SO, Breton J, Tennoune N, et al. Gut Commensal E. coli Proteins Activate Host Satiety Pathways following Nutrient-Induced Bacterial Growth. Cell Metabolism . 2015