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Why Some People Gain Weight and Others Don't

Published: 2022-12-26 - Updated: 2023-01-03
Author: University of Copenhagen | Contact: nexs.ku.dk/english/
Peer-Reviewed Publication: Yes | DOI: https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-022-01418-5
Additional References: Digestive Disorders Publications

Synopsis: Research suggests some of the population has a composition of gut microbes that extracts more energy from food than the microbes in the gut of others. From mouth to esophagus, stomach, duodenum, small intestine, large intestine, and finally to the rectum, the food we eat takes a 12-to-36-hour journey, passing several stations along the way, before the body has extracted all the food's nutrients. Interestingly, the group with less energy left in their stool also weighed more on average.

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Definition

Gut Bacteria

Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. Inside your gut are 300 to 500 different bacteria containing nearly 2 million genes. Paired with other tiny organisms like viruses and fungi, they make what's known as the microbiota, or the microbiome.

  • Everyone has a unique composition of gut bacteria - shaped by genetics, environment, lifestyle, and diet.
  • Gut bacteria in the colon serve to break down food parts that our body's digestive enzymes can't, e.g., dietary fiber.
  • The collection of gut bacteria, called the gut microbiota, is like an entire galaxy in our gut, with a staggering 100 billion of them per gram of stool.
  • Humans can be divided into three groups based on the presence and abundance of three main groups of bacteria that most of us have: B-type (Bacteroides), R-type (Ruminococcaceae), and P-type (Prevotella).

Main Digest

Stool Energy Density is Positively Correlated to Intestinal Transit Time and Related to Microbial Enterotypes.

The research is a step towards understanding why some people gain more weight than others, even when they eat the same.

Related Publications:

Unfair as it is, some of us seem to put on weight just by looking at a plate of Christmas cookies, while others can munch away with abandon and not gain a gram. Part of the explanation could be related to the composition of our gut microbes. This is according to new research conducted at the University of Copenhagen's Department of Nutrition, Exercise and Sports.

Researchers studied the residual energy in the feces of 85 Danes to estimate how effective their gut microbes are at extracting energy from food. At the same time, they mapped the composition of gut microbes for each participant.

The results show that roughly 40 percent of the participants belong to a group that, on average, extracts more energy from food compared to the other 60 percent. The researchers also observed that those who extracted the most energy from food also weighed 10 percent more on average, amounting to an extra nine kilograms.

"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," says Associate Professor Henrik Roager of the University of Copenhagen's Department of Nutrition, Exercise and Sports.

Associate professor Henrik Roager in the lab - Image Credit: University of Copenhagen.
Associate professor Henrik Roager in the lab - Image Credit: University of Copenhagen.

May Increase Risk of Obesity

The results indicate that being overweight might not just be related to how healthily one eats or how much exercise one gets. It may also have something to do with the composition of a person's gut microbes.

Participants were divided into three groups based on the composition of their gut microbes. The so-called B-type composition (dominated by Bacteroides bacteria) is more effective at extracting nutrients from food and was observed in 40 percent of the participants.

Following the study, the researchers suspect that a portion of the population may be disadvantaged by gut bacteria that are too effective at extracting energy. This effectiveness may result in more calories available for the human host from the same amount of food.

"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," says Henrik Roager.

Short Travel Time in The Gut Surprises

From mouth to esophagus, stomach, duodenum, small intestine, large intestine, and finally to the rectum, the food we eat takes a 12-to-36-hour journey, passing several stations along the way before the body has extracted all the food's nutrients.

The researchers also studied the length of this journey for each participant, who had similar dietary patterns. Here, the researchers hypothesized that those with long digestive travel times would be the ones who harvested the most nutrition from their food. But the study 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," says Henrik Roager.

Confirms Previous Study in Mice

The new study in humans confirms earlier studies in mice. In these studies, it was found that germ-free mice that received gut microbes from obese donors gained more weight compared to mice that received gut microbes from lean donors, despite being fed the same diet.

Even then, the researchers proposed that the differences in weight gain could be attributable to the fact that the gut bacteria from obese people were more efficient at extracting energy from food. This is the theory now being confirmed in the new study by the Department of Nutrition, Exercise and Sports.

"It is very interesting that the group of people who have less energy left in their stool also weigh more on average. However, this study doesn't prove that the two factors are directly related. We hope to explore this more in the future," says Henrik Roager.

About the Study

Reference Source(s):

Why Some People Gain Weight and Others Don't | University of Copenhagen (nexs.ku.dk/english/). Disabled World makes no warranties or representations in connection therewith. Content may have been edited for style, clarity or length.

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Cite This Page (APA): University of Copenhagen. (2022, December 26). Why Some People Gain Weight and Others Don't. Disabled World. Retrieved January 27, 2023 from www.disabled-world.com/health/digestive/gut-microbiota.php

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