Bugs That Keep You Thin!

Malea Parnow

My project is about the microbiome in the human gut and how it can relate to obesity. I discovered that many people around the world and especially in the US are eating high-energy foods and not exercising enough to compensate for the Calories they ingest and they are ingesting foodsthat are not easily digestible by the human body. The microbiota ferment the indigestible nutrients and turns them into fatty acids that the body usually cannot use.
A new topic of research is coming out about how antibiotics, probiotics, and prebiotics can help change the gut microbiome to help curb the obesity epidemic.

I was interested in maintaining a healthy lifestyle and what types of microorganisms would assist in that goal. I found that when our energy input is greater than our energy expenditure, obesity can result. This was pretty much common sense so I looked into why this is so. This results because the body is incapable of maintaining homeostasis and as such, fat results. Gut microbiota ferment indigestible carbohydrates into short chain fatty acids that provide excess energy to the body (Arora, T. and Sharma, R. Feb. 2011). New prebiotics and probiotics are being developed to change the gut microbiome to help curb obesity. Probiotics are beneficial bacteria that can be found in different foods and prebiotics are non-digestible foods that help “good bacteria” grow in the gut (Jegtivig, S. May 2011). Many members of my family are health nuts and they rubbed off on me and after being in this class I became much more interested in what microbes are doing in my body.

Obesity is a pandemic in American society. Many people reach obesity and for some it is a medical condition or a medication problem but for others the cause may be unknown. Well, I may have found a cause! The microbiota in our gut ferment indigestible carbohydrates which give our body excess energy and unless we are star athletes, this can contribute to weight gain and fat build up. It is very important that our bodies stay within a homeostatic range in energy intake and expenditure because when these things are out of balance we either end up with excessive weight gain or loss.


When we eat we have energy intake. When we exercise we release energy and when we produce heat to maintain temperature homeostasis we also release energy. We measure energy intake and expenditure in Calories (with a capital C!). When we experience imbalance we can either have gaining imbalance or losing imbalance. Gaining imbalance is a result of energy intake being higher than what is used in external work and internal expenditure. Losing imbalance is when energy intake is less than what is used in external work and internal expenditures (Wikipedia 2011).

The distal gut is one of the most densely populated and most surveyed bacterial ecosystems in nature (Jian 2007). Without these microorganisms we would not be able to break down many parts of our food such as certain polysaccharides and lipids. Antibiotics and other drugs people take affect the conditions for our normal microbiota and can cause them to die. These same microbiota can cause obesity if we eat too many carbs. The carbohydrates are fermented into short chain fatty acids that provide excess energy which, as we learned earlier, can lead to obesity.

New research has been initiated into probiotics and prebiotics, which are types of microorganisms and foods that can help the gut microbiome to help curb the obesity epidemic. These “biotics” help “good” bacterial growth in the human gut. Probiotics are often found in fermented foods such as yogurt and sauerkraut while prebiotics can be found in foods with oligosaccharides which are hard for our bodies to digest so the “good” bacteria can use them to grow. These foods include fruits, legumes, and whole grains(Jegtvig 2011). Antibiotics can also be used to change microbial growth in the gut to slow or inhibit the fermentation of indigestible carbohydrates into fatty acids.

Earlier studies focused on genomics and endocrinology to discover the underlying mechanisms of body-weight regulation, application of metagenomic methods has provided further insights into the diversity of the gut microflora and its role in the regulation of energy homeostasis (Arora and Sharma 2011). This is an exciting and important new area of study. While it is my personal belief that people in general really do need to exercise more, it could also be extremely important to know that you have the proper microbiota residing in your gut and that it is not causing excessive weight gain.

Literature Cited:
· Arora, Tulika and Sharma, Rajkumar. Fermentation Potential of the Gut Microbiome: Implications for Energy Homeostasis and Weight Management. Published online in Nutrition Reviews Vol. 69, Issue 2, p99-106 (Feb. 2011)
· Jegtvig, Shereen. Prebiotics and Probiotics. Published online on About.com/Nutrition. (May 2011)
· Jian Xu, Michael A. Mahowald, Ruth E. Ley, Catherine A. Lozupone, Micah Hamady, Eric C. Martens, Bernard Henrissat, Pedro M. Coutinh, Patrick Minx, Philippe Latreille, Holland Cordun, Andrew Van Brunt, Kyung Kim, Robert S. Fulton, Lucinda A. Fulton, Sandra W. Clifton, Richard K. Wilson, Robin D. Knight, Jeffrey I. Gordon. Evolution of Symbiotic Bacteria in the Distal Human Intestine. Published online in PLOS Biology Volume 5, Issue 7 p. 1574-1586 (July 2007)
· Tortora, Funke, Case. 2010. Microbiology: An Introduction. Pearson Education Inc., CA., 812pp.
· Unknown. The Era of Biotics. Published online on AudioDigest, Gastroenterology, Vol. 25, Issue 01 (Jan. 2011)
· Energy Balance, Biology. Published on Wikipedia. Feb. 2011