08/09/2015 10:31 EDT | Updated 08/09/2016 05:59 EDT

How Bacteria Could Help Weight Loss Surgery Success


Obesity has been a rising problem for decades. In Canada, 25 per cent of adults and one in ten children are clinically defined as suffering from this chronic condition.

Controlling obesity is never an easy prospect and for some, the best option is to undergo bariatric surgery. The practice has been around since the 1960s and involves restricting the volume of the stomach either with a band or through surgical removal of a large part of the stomach organ. This inevitably reduces the ability of the body to take in food. Over time, with fewer calories, weight drops.

But food intake levels are only part of the reason behind the improvement of health. There are more complex ways the body deals with the reduction in size. Changes occur in the way patients feel hunger, use up nutrients like glucose, and even think about food in the brain leading to different food choices. For the most part, this is all positive and eventually leads to the anticipated reduction in weight and fat content.

There's also another factor in determining the benefit of this surgery: the microbes living in the gut. The tens of trillions of bacteria can also be affected by the change. Although this was known hypothetically for years, in 2010, it was shown for the first time.

Back then, the results suggested the microbiological nature of the population shifted as if the body was starving. The bacterial species capable of surviving a reduction in food survived and increased in number. Those looking for more simple nutrients tended to reduce dramatically. This suggested the bacteria were innocent bystanders and played only a reactionary role.

A year later, the theory was reversed suggesting the bacteria may indeed have an influence on the body after surgery. A team of researchers from the UK revealed an increase in the crosstalk between the gut and the microbes in rats. The bacteria in the gut played a greater role in digestion by increasing the level of fermentation in the intestines. This in turn released a number of byproducts the body recognizes as signals. For the most part, these signals were associated with weight loss, appetite suppression and increased energy use.

The animal study suggested there may be more to the microbial picture in the human context yet little was done until this past week when a European group of researchers examined exactly how these bacteria contribute to weight loss. Their results reveal the bacteria can not only regulate fat mass in the patient but may also be transferred to another individual and offer the same benefits.

The process was rather simple. The researchers sought fecal samples from 14 women all of whom had undergone bariatric surgery. They then took the samples back to the lab and examined them. The focus was on population structure and the potential to provide the body with fermentation byproducts.

As expected, the bacteria from the women provided the same results as seen in the rats. The populations had changed dramatically with an increase in fermentation. The same types of byproducts were also formed suggesting an increased benefit to the women from the bacteria themselves.

But that was only half of the work. The authors wanted to find out if all of these observations were actually helping to reduce fat and weight. The only way they could accomplish this was through fecal transplantation, which they did in mice. The practice was less than appetizing as the mice were directly fed the fecal matter. This may appear to be cruel but considering mice are coprophagic, they probably didn't mind.

The test mice were fed fecal matter from women after the operation. As a comparison, control mice were also fed feces but this came from the women before they underwent the surgery. After two weeks, the results were astounding. The test mice lost between 26 and 43 per cent more body fat than the controls. The only difference was the bacterial population in the gut. The team showed for the first time the bacteria were indeed directly contributing to weight loss.

Even with the positive outcome of the study, the authors were quick to note this is just the beginning and more studies need to be performed before we can figure out exactly which bacteria are best for weight loss in combination with surgery. Yet, there is no denying the importance of the gut microbes in making this procedure a success. With more research, the right combination of bacteria may be found to act as a form of post-surgical probiotic supplement. This could help not only to quicken the effects of the surgery but also, improve the condition in the gut over the long term.


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