(13-06-12) Written by: Kevin Cann

So many people are told to eat less and exercise more when weight loss is the ultimate goal. We often assume that the greatest problem we face is lack of physical activity and easy access to high calorie, low quality food. In some cases this definitely may be the problem. Put down the bag of chips and do some exercise and you may see some weight loss. This weight loss may or may not be permanent, and in some cases there may even be weight gain. Why is it that people eat less and exercise more, but can?t sustain weight loss? There are a number of issues that can cause this scenario.
One of the answers to that question is buried right in the place that is giving us so many problems; our gut. In our gut there are two main types of bacteria: bacteroidetes and firmicutes. Studies have shown in mice and in humans that the bacterial makeup of the intestines differs between obese and lean subjects. Animal studies and human studies have shown that obese people have lower bacteroidetes and higher levels of firmicutes, but there is some contradictory data out there on gut bacteria composition (Harris, 2011). The bacterial makeup of the gut in obese individuals has been shown to actually increase the amount of energy extracted from food. This has been shown in experiments with mice where the gut flora of obese mice was switched with lean mice. The obese mice lost weight and the lean mice gained weight. Studies such as these show that obesity is a pathophysiological disease (Turnbaugh, 2006).
This change in gut flora can be the cause of us overeating. Andrew Gewirtz showed that insulin resistance and increased appetite can be transferred from mouse to mouse in an experiment that he ran. He even goes on to state in that study that he believes overeating is not just a matter of not having will power, but the gut bacterial makeup is what is driving the appetite (Vijay-Kumar, 2010).
Obesity has also been linked to many disorders such as cardiovascular disease and cancer. The interesting part is that poor gut flora has also been linked to the same diseases. One cause is our body?s immune response to the bacterial endotoxin, lipopolysaccharide (LPS). Our body responds by initiating an inflammation response. The resulting inflammation can suppress our immune system and leave us open to illness. Also, low grade inflammation from LPS has been linked to insulin resistance in studies (Wellen, 2004). The other factor is our gut bacteria have evolved with us.
One way bacteria have evolved is in their ability to extract energy from indigestible fiber. Jumpertz did a study comparing stool energy to energy consumed while feeding subjects meals that varied in caloric content and observing changes in gut microbiota. He concluded that with a 20% decrease of bacteroidetes and a 20% increase of firmicutes there was an increase in energy harvest of around 150 calories (Jumpertz, 2011). That study shows one way for counting calories to be ineffective, how can one person know what their energy expenditure truly is?
Our gut bacteria are not only 84% of our immune system, but they also have the ability to drive our appetite for high calorie foods, increase the amount of systemic inflammation we face, and also extract more calories from the foods we are eating. A primary goal of any weight loss program should be to focus on foods that heal the gut. Typically ?bad? bacteria like to feed off of sugar and refined carbohydrates, while our ?good? bacteria feed off of fruits and vegetables. This makes sticking with a paleo diet for 30 days even more important. That way the good bacteria can overtake the bad bacteria and allow our gut to heal.
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References
K. E. Wellen and G. S. Hotamisligil (2005), Inflammation, stress, and diabetes. The Journal of Clinical Investigation, vol. 115, no. 5, pp. 1111?1119, 2005.
R. Jumpertz, D. S. Le, P. J. Turnbaugh et al. (2011). Energy-balance studies reveal associations between gut microbes, caloric load, and nutrient absorption in humans. American Journal of Clinical Nutrition, vol. 94, no. 1, pp. 58?65, 2011.
M. Vijay-Kumar et al. Altered Gut Microbiota in Toll-Like Receptor-5 (TLR5) Deficient Mice Results in Metabolic Syndrome. www.pubmed.gov. Retrieved on May 7, 2012.
Turnbaugh, Peter (2004). An obesity associated gut microbiome with increased capacity for energy harvest.
Harris, Kristina (2012). Is the gut microbiota a new factor contributing to obesity and its metabolic disorders? Journal of Obesity. Retrieved on May 1, 2012.
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Kevin Cann is owner of Genetic Potential Nutrition. He is a holistic nutritionist, wellness coach, and strength coach. He works with people fighting illness, to competitive athletes. Check out his site at www.geneticpotentialnutrition.com.

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