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Some gut bacteria promote obesity

According to a new study led by the University of Copenhagen in Denmark, being overweight may not be related only to how healthy one eats or how much exercise one gets, but also to the particular composition of a person’s gut microbiome. Surprisingly, the experts found that a portion of the population may be disadvantaged by gut bacteria that are highly effective at extracting energy from food.

The scientists investigated the residual energy in the stool of 85 participants to estimate how effective their gut microbes were at extracting energy from food. The analyses revealed that about 40 percent of the participants had a greater abundance of Bacteroides bacteria in their gut microbiome (a so-called B-Type composition), which are more effective at extracting nutrients from food. However, this effectiveness may also result in more calories available for the human host from the same amount of food, a finding previously confirmed by studies of mice.

“The fact that our gut bacteria are great at extracting energy from food is a good thing, as the bacteria’s metabolism of food provides extra energy in the form of, for example, short-chain fatty acids, which are molecules that our body can use as energy-supplying fuel. But if we consume more than we burn, the extra energy provided by the intestinal bacteria may increase the risk of obesity over time,” explained study senior author Henrik Roager, an expert in the Microbiome and Metabolomics at Copenhagen.

By studying how the composition of the gut microbiome is related to the length of food’s journey from consumption to excretion (which can last between 12 and 36 hours), the scientists stumbled upon another unexpected discovery: while they initially hypothesized that people with long digestive travel times would be the ones who harvested the most nutrition from their food, the analysis found the exact opposite.

“We thought that there would be a long digestive travel time would allow more energy to be extracted. But here, we see that participants with the B-type gut bacteria that extract the most energy, also have the fastest passage through the gastrointestinal system, which has given us something to think about,” Roager said. 

“We may have found a key to understanding why some people gain more weight than others, even when they don’t eat more or any differently. But this needs to be investigated further,” he concluded.

The study is published in the journal Microbiome.

By Andrei Ionescu, Staff Writer

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