Your Gut Gas Could Be Making You Absorb More Calories

A little-known microbe in your gut produces methane and may help your body extract more calories from food, according to a study led by Arizona State University.

Deep inside your gut lives a vast community of microbes, and among them is one unusual resident that produces methane. This lesser-known methane-producing microbe may influence how efficiently your body absorbs calories from food, according to new research from Arizona State University.

This community of microbes is collectively known as the microbiome. In some people, the gut microbiome generates large amounts of methane, while in others it produces very little.

Researchers discovered that individuals with methane-rich microbiomes appear to be especially efficient at extracting extra energy from high-fiber foods. This difference could help explain why people absorb varying numbers of calories from the same types of food once it reaches the colon.

Importantly, the scientists emphasize that fiber itself is not the problem. Regardless of methane levels, people tend to absorb more calories from a Western-style diet filled with processed foods. High-fiber diets still lead to fewer calories being absorbed overall, although the exact amount depends on how much methane a person’s gut microbes produce.

Insights from this study could be a foundation for personalized nutrition.

The Methane Connection

“That difference has important implications for diet interventions. It shows people on the same diet can respond differently. Part of that is due to the composition of their gut microbiome,” says Blake Dirks, lead author of the study and graduate researcher at the Biodesign Center for Health Through Microbiomes. Dirks is also a PhD student in ASU’s School of Life Sciences.

The study, published in The ISME Journal, found that methane-producing microbes called methanogens are associated with a more efficient microbiome and higher energy absorption from food.

One of the microbiome’s main jobs is helping to digest food. Microbes ferment fiber into short chain fatty acids, which the body can use for energy. In the process, they produce hydrogen. Too much hydrogen pauses their activity, but other microbes can help keep this process going by using up the hydrogen.

Methanogens are hydrogen-eaters. As they consume hydrogen, they create methane. They are the only microbes to make this chemical compound.

“The human body itself doesn’t make methane, only the microbes do. So we suggested it can be a biomarker that signals efficient microbial production of short-chain fatty acids,” says Rosy Krajmalnik-Brown, corresponding author of the study and director of the Biodesign Center for Health Through Microbiomes.

The research suggests that these microbe interactions affect the body’s metabolism. The team found that higher methane production was associated with more short-chain fatty acids being made and absorbed in the gut.

In the experiment, researchers provided each study participant with two different diets. One diet had more processed foods and low fiber. The other diet was high in whole foods and fiber. Both diets contained the same proportion of carbs, proteins, and fats.

Inside the Calorimeter: Measuring Human Metabolism

ASU researchers collaborated with the AdventHealth Translational Research Institute to use a unique facility for their experiment. For six days, each participant lived inside a sealed, hotel-like room called a whole-room calorimeter that measured their body’s metabolism and methane output. Other experiments rely on a single breath test to measure methane.

The team’s method can gather more comprehensive data. It captures methane that the body emits as breath and gas (ahem), rather than just breath, and over a continuous period, rather than a single moment.

“This work highlights the importance of the collaboration between clinical-translational scientists and microbial ecologists. The combination of precise measures of energy balance through whole-room calorimetry with ASU’s microbial ecology expertise made key innovations possible,” says Karen D. Corbin, a co-author and associate investigator at the institute.

Data from blood and stool samples measured how much energy participants’ bodies absorbed from food and tracked their microbes’ activity. The team compared data from people whose gut microbiomes produced high versus low methane levels.

On the high-fiber diet, almost everyone absorbed fewer calories than they did on the processed-food diet. But those whose guts produced more methane absorbed more calories from the high-fiber diet than those whose guts produced less methane.

This research creates a foundation for future studies and medical treatments.

“The participants in our study were relatively healthy. One thing that I think would be worthy to look at is how other populations respond to these types of diets — people with obesity, diabetes, or other kinds of health states,” Dirks says.

Study participants weren’t intended to lose weight during the experiment, though some lost a little while on the high-fiber diet. The team is interested in seeing how methanogens in the microbiome impact a diet that is intentionally aimed at helping participants lose weight.

“You can see how important it is that the microbiome is personalized,” Krajmalnik-Brown says. “Specifically, the diet that we designed so carefully to enhance the microbiome for this experiment had different effects on each person, in part because some people’s microbiomes produced more methane than others.”

Reference: “Methanogenesis associated with altered microbial production of short-chain fatty acids and human-host metabolizable energy” by Blake Dirks, Taylor L Davis, Elvis A Carnero, Karen D Corbin, Steven R Smith, Bruce E Rittmann and Rosa Krajmalnik-Brown, 22 May 2025, The ISME Journal.
DOI: 10.1093/ismejo/wraf103

This project was funded by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

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