The composition of a person’s gut microbes may help to explain why some people put on weight more easily than others, according to a new study.

Research coming out of the University of Copenhagen’s Department of Nutrition, Exercise and Sports shows some people possess a particular composition of gut microbes which, on average, extract more energy from food.

Associate Professor Henrik Roager of the University of Copenhagen’s Department of Nutrition, Exercise and Sports 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.”

The researchers mapped the composition of gut microbes belonging to 85 Danes, aged between 22 and 66, whilst simultaneously studying the residual energy in their faeces to work out how effectively their gut microbes extracted energy from food.

About 40 per cent had the B-type composition, dominated by Bacteroides bacteria, which extracted more energy from food, compared with the rest of the group.

On average, those with the B-type composition weighed 10 per cent more than the rest of the participants.

The results indicate that being overweight may be connected to the composition of someone’s gut microbes as well as how healthily a person eats or how much exercise they get.

Professor Roager added: “The fact that our gut bacteria are great at extracting energy from food is basically 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.”

The researchers also studied the length of time it took for food to pass through the bodies of the study participants, all of whom had similar dietary patterns.

The researchers suspected that people with long digestive travel times would reap the most nutrition food but the study found the exact opposite.

The participants whose gut microbes extracted more energy also had the fastest passage through the gastrointestinal system.

The study was published in Microbiome Journal.

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