Methane on the Breath Is an Indication of Obesity

Methane gas on the breath is a sign of obesity, Time reports. The human nose cannot detect methane, but scientists know it’s there and hope to use it to help get a handle on the obesity epidemic.

Obesity’s methane comes from a certain kind of gut microbe sometimes found in obese animals in studies. To see if these results also applied to humans, researchers from the Cedars-Sinai Medical Center analyzed the breath of nearly 800 men and women. The researchers found that significantly higher levels of methane in the participants’ breath equated with, on average, a body mass index around 2.4 points greater than average. Participants with methane breath also had about six percent more body fat than those lacking abnormal levels of the gas.

The culprit, she believes, is a member of archaea known as Methanobrevibacter smithii, which is present in the intestinal tract of about 70% of people, but elevated in about 30%. It’s that smaller group of individuals who might be genetically predisposed to harboring levels of M. smithii that might put them at higher risk of developing obesity.

A growing group of scientists think that microbes play significant roles in obesity. In this case, a simple breath tests could identify patients with abnormal levels of M. smithii, Time writes. The researchers hope that their findings may give clues about how to manipulate the gut microbiome in ways that help obese patients lose weight.

Ed. note: This post has been updated from its original text. Thanks to @KateHarding, @laurakeet and others for their feedback.

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Rachel Nuwer is a freelance science writer based in Brooklyn.