Of course the gut plays a role in eating! It’s the place where all the food goes! However, could there be another factor beyond simple digestion? There are trillions of bacteria in your stomach and intestines that make up the gut microbiome, which according to new research, could be the source of hunger and crucial to weight control. The hundreds of species of microorganisms in your gut are able to release enzymes, neurotransmitters, and even hormones that all work in conjunction with your brain, which, along with the vagus nerve, help create the gut-brain connection(1). Listed below are examples of just some of the many ways that your gut and eating behavior may influence each other.
Gut microbiome could affect hunger hormones and the brain.*
Known as the “second brain”, the gut can have a significant impact on how you behave and might even control appetite. Medical researchers from Virgen de la Victoria Hospital in Spain(2) tested this appetite hypothesis on rats and found an association with gut bacteria and hunger hormones.
The team of scientists split a sample of rats into separate groups: those given a restricted diet versus those given no diet restrictions. They then analyzed fecal bacteria composition of both groups and compared the quantities of bacteria to the levels of two hunger hormones, leptin and ghrelin, of which leptin signals fullness and ghrelin signals hunger. It was found that having an abundance of certain species of bacteria correlates with an increase in leptin, while an abundance of other species correlates with an increase in ghrelin.
Microbiome have the potential to affect obesity and weight gain.*
Exciting research is being done on obesity that could teach us more about how to manage it. For example, scientists at Vanderbilt University (2) experimented with a species of bacteria that was altered by the researchers to produce a substance used by the body to make a special fat molecule. This altered bacteria was incorporated into the gut microbiome of randomly chosen mice. After eight weeks, the scientists found that the mice with modified bacteria had suppressed appetite and lower levels of obesity compared to mice without the bacteria (3). Moreover, when given to already obese rats, the modified bacteria inhibited further weight gain. While these trials are far from conclusive, they do demonstrate the potential power of the gut microbiome in regulating weight.
Another group from Louisiana State University tested the effects of an obese-like diet with high fat on gut microbiome by placing rats in groups with high fat diet or a controlled normal diet. The rats with high fat diets were found to have different gut microbiomes and were also showing compulsive, anxiety-like behavior possibly stemming from changes in the brain caused by gut composition. (4)
Blood sugar and exercise may have correlation with certain bacteria.*
Blood sugar control and exercise are important for everyone, but especially for people at risk for diabetes and obesity. New publications are showing that unhealthy habits may impact your gut microbiome.
The University of Tartu in Estonia sponsored research (5) that analyzed a sample of elderly patients for BMI, blood sugar, and gut microbiome. The results showed that patients with normal BMI had higher total counts of gut bacteria as compared to overweight and obese patients. Also, higher blood sugar levels decreased certain types of beneficial gut bacteria.
Similar to the study done by Louisiana State University on high fat diets, the Mayo Clinic of Jacksonville, Florida also tested the effect of high fat diets on microbiome, except they also added the variable of exercise. Mice were randomly split into groups and assigned exercise levels: high fat low exercise, high fat high exercise, normal diet high exercise, and normal diet low exercise. After analyzing the gut microbiomes of all mice, researchers found that the high fat diet and variations in exercise both independently altered bacterial diversity, suggesting the importance of both to a healthy gut. (6)
All this research can be hard to keep up with, however, one thing is clear – the gut microbiome and its connection with the brain has the potential to be key in learning about how we eat.
(1) J Med Food. 2014 Dec; 17(12):1261-72. doi: 10.1089/jmf.2014.7000.
(2) PLoS One. 2013 May 28; 8(5):e65465. doi:10.1371/journal.pone.0065465. Print 2013.
(3) J Clin Invest. 2014 Aug; 124(8):3391-406. doi:10.1172/JCI72517. Epub 2014 Jun 24
(4) Biol Psychiatry. 2015 Apr 1; 77(7):607-15. doi:10.1016/j.biopsych.2014.07.012. Epub 2014 Jul 18.
(5) Microb Ecol Health Dis. 2014 Jun 3;25. doi: 10.3402/mehd.v25.22857. eCollection 2014.
(6) Mol Neurodegener. 2014 Sep 13;9:36. doi: 10.1186/1750-1326-9-36.
*These statements have not been evaluated by the Food and Drug Administration (FDA). These products are not intended to diagnose, treat, cure or prevent any disease.