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A breath test for... obesity?

A standard breath test that looks for bacterial growth in the gut could spot those with a greater risk of a certain type of obesity.

Wikimedia Commons

Researchers have been exploring breath tests for all sorts of uses -- from sniffing out everything from lung cancer to heart disease to diabetes. But testing for obesity? Could that really be possible?

Ruchi Mathur is the director of the Diabetes Center in the Division of Endocrinology, Diabetes and Metabolism, and an endocrinologist at the Weight Loss Center at Cedars-Sinai. Cedars-Sinai

According to a new study in the April issue of the Journal of Clinical Endocrinology & Metabolism, the bacterial overgrowth that can be caught by a standard breath test may also reveal one's body fat percentage.

Apparently when one's microbiome (the complex infrastructure of good and bad bacteria that live in and on us) gets out of balance, with the bad bacteria outperforming the good, people can experience constipation, bloating, diarrhea, etc. But this new research finds that the imbalance also correlates with obesity.

"Normally, the collection of microorganisms living in the digestive tract is balanced and benefits humans by helping them convert food into energy," said lead author Ruchi Mathur at the Division of Endocrinology at Cedars-Sinai in Los Angeles. "When [the microorganism called Methanobrevibacter smithii] becomes overabundant, however, it may alter the balance in a way that makes the human host more likely to gain weight and accumulate fat."

Specifically, the test would look for high concentrations of hydrogen and methane gases, the combination of which indicates that M. smithii has colonized the digestive tract. (Previous research has already shown that M. smithii is the predominant organism in the human gastrointestinal tract responsible for methane production.)

In this study, almost 800 participants had their body fat measured using BMI (which looks at height and weight) and low-wattage electrical conductivity (which differentiates between fat and lean tissue). They then drank a sugary syrup and took a breath test every 15 minutes for two hours.

Those with higher BMIs and more body fat exhaled higher levels of methane and hydrogen, while those with lower BMIs and body fat had either lower levels of each gas or a higher concentration of only one of the two gases.

Mathur said obesity is not a one-size-fits-all disease, but looking for methane and hydrogen concentrations in one's breath could help identify whether an obese person may be more likely to respond to specific weight loss programs.

It remains unclear whether modifying the bacteria in the gut will help anyone lose weight faster or easier, but researchers seem to agree it's worth exploring further.