New evidence for the relationship between obesity and the microbiome

Obesity is rapidly becoming a big problem in the United States (no pun intended), and up to one-third of adults are obese, according to the Centers for Disease Control and Prevention. As a disease, obesity is not well understood because there are so many factors that are involved in weight control, including caloric intake, genetic predisposition, and psychological factors among many others. A study done by researchers at the Institute of Nutritional Sciences, of the University of Vienna, and recently published by Beneficial Microbes, considers another factor involved in obesity: the microbiome.  Previous research on mice has shown that the microbiome is associated with obesity and leanness, and that diet can be an important tool to modulate it.  These researchers extended some of these ideas to humans, and studied the microbiomes of obese people as they lost weight through diet and exercise.

The researchers studied 33 obese participants during a four month period of strict diet and exercise regime, which resulted in weight loss. Fecal samples were collected once before, during, and after the study and the bacterial content was tested.

A decisive difference in the bacterial content of the gut was found in individuals before the study and after weight loss. Significant findings of this study include the increased presence of Lactobacilli after weight loss, a genera that has been found to have probiotic, anti-inflammatory characteristics.  The study also found that weight loss was associated with a decrease in the ratio of Firmicutes to Bacteroidetes, with the abundance of Firmicutes increasing in presence and the abundance of Bacteroidetes remaining the same.  Interestingly, the amount of weight lost was related to the amount decrease in this ratio.  Finally, the scientists found that Archaea, which are a distinct phylogenetic domain from Bacteria and Eukaryotes, increased in abundance after weight loss.

As we know, the microbiome holds a lot of promise in the fight against obesity, and this study, as well as those that are sure to follow, could impact obesity treatments in the future.  We need to remember, though, that far more rigorous studies are needed before any actionable strategies to modulate the microbiome to lose weight are established.  Perhaps though, the key to achieving a healthy weight is to maintain a certain level of bacterial diversity in the gut.

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