Is Eating Behavior Controlled by Our Gut Microbiome?

Are our cravings controlled by the tiny little microorganisms that live in our gut? These tiny microorganisms, also called gut bugs, may be controlling our bodies more than we know. We literally have trillions of these tiny organisms living in our gut. Research has come to find out that these microorganisms may communicate with our brains via the gut-brain axis, also known as the vagus nerve. Like any living organism these gut bugs need to eat, and they thrive when given certain types of food. Studies show they may communicate with our brains, and since what they eat depends on what we eat, it might be possible that they send signals to our brains to crave foods that they want to eat. We are a host to these tiny organisms, and we may have food cravings due to the signals these gut bugs send to our brain telling us to eat certain foods.

Our Gut is Sending Signals to Our Brain

That is a lot to think about! Before we get too far into this discussion, we need to talk a bit more about the gut bugs that compose our gut flora. There are about 100 trillion microorganisms that live in our gut. If they all are sending signals to the brain to tell us to eat different types of foods, what messages do we get? Are they all sending signals at once? This is where the situation gets really interesting; research points to the fact that some people have more of certain types of microorganisms that live inside their guts than others. Like a fingerprint, no two gut microbiomes are the same. Some people have a very diverse gut bug population while others have a less diverse population of these gut microbes.

Survival of the Fittest Microorganisms

So, which is better, a more diverse population of gut bugs or a less diverse population? Research shows that a more diverse population is better for overall health, but the real advantage of a diverse microbiome is that having different bacterial strains tames the microbes ability to control our eating behavior through neurotransmitter signals. With a diverse population of gut bugs living in our gut, we have a situation where different colonies all must compete with one another. That simply means these organisms expend energy to compete with one another for survival, and the level of neurotransmitter signals may be limited.

A Diverse Microbiome is Best

On the contrary, a less diverse community of microbes means that certain colonies of these organisms start to thrive and outcompete other strains. Once this occurs the larger, more dominant microbes are able expend energy in other ways, like communication with the brain. Now these larger colonies start to gain control over the signals sent to our brains, like what to eat, and hence are fed the foods they desire so they can get even stronger. This could lead to a runaway effect where a specific microbe keeps getting stronger and greater in number. It’s like trying to control a weed population in your garden. If you have done any gardening you know that once an invasive species starts to gain momentum, it is very difficult to get rid of it. Same thing with your gut bacteria.

So if we have a gut microbiome that is not diverse, we may be subject to eating foods that the dominant microbes desire, and that food might not be particularly good for us. Could this lead to overeating, or even obesity? Do you crave certain foods? Of course you do, we all do. However, to think that these cravings may be due to our gut microbiome is a fascinating question.

Are we Overweight Due to Gut Health?

Many believe that overeating is due to lack of willpower or self control. However, maybe there is more to the story, a bigger picture going on. When we have an unhealthy gut microbiome, we may have a situation where microorganisms are sending signals for us to eat unhealthy food. On the other hand, some Lactobacillus probiotics are said to reduce fat mass. Similarly, Bifidobacterium breve have been shown to slow weight gain in mice that were given a high fat diet. So, the logic follows that other types of bacteria can have the opposite effect or cause us to gain weight by controlling our eating habits through cravings.

We do know that microbes can manipulate our behavior. Some people like chocolate while other folks are indifferent. As a whole, scientists have found that people that like chocolate generally have a different microbiota than the people indifferent to chocolate. Again, this points to the possibility of the gut microbiome causing a preference for chocolate (my microbes must really like chocolate!)

Do you CRAVE Chocolate?

In another controlled trial it was found that mood was significantly improved by giving the subjects Lactobacillus casei. It may be within reason to say that if these microbes can control our mood and desire for chocolate, then they can also control our eating behavior. These microbes may be partially to blame for the obesity epidemic in this country. 

If microbes can influence our eating habits, then doesn’t it make sense to learn about which microbes encourage positive or healthy habits?

Bibliography

Alcock J, Maley CC, Aktipis CA. Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. BioEssays. 2014;36(10):940-949. doi:10.1002/bies.201400071

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