Some patients do not experience the optimal weight loss from bariatric surgery and researcher presented at the 97th annual meeting of the Endocrine Society in San Diego, suggests that the presence of a specific methane gas-producing organism in the gastrointestinal tract may account for a decrease in optimal weight loss. The study entitled, "Intestinal Methane Production is Associated with Decreased Weight Loss Following Bariatric Surgery" was presented by Dr Ruchi Mathur, director of the Diabetes Outpatient Treatment and Education Center at Cedars-Sinai.

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Ruchi Mathur

"We looked at 156 obese adults who either had Roux-en-Y bypass surgery or received a gastric sleeve. Four months after surgery we gave them a breath test, which provides a way of measuring gases produced by microbes in the gut," said Mathur. "We found that those whose breath test revealed higher concentrations of both methane and hydrogen were the ones who had the lowest percentage of weight loss and lowest reduction in BMI when compared to others in the study."

In total, 13 of the patients tested positive for methane and hydrogen. On average, the decrease in their body-mass index, was slightly more than 20 percent compared to 23.5 percent for the other patients.

The methane-producing microorganism methanobrevibacter smithii is the biggest maker of methane in the gut, she explained, and may be the culprit thwarting significant weight loss in bariatric patient. While that research continues, bariatric patients may still have options to improve weight loss after surgery.

"Identifying individuals with this pattern of intestinal gas production may allow for interventions through diet. In the future there may be therapeutic drugs that can improve a patient's post-surgical course and help them achieve optimal weight loss," said Mathur. “Our new study suggests that gastrointestinal colonization with methanogens makes it harder to lose weight after bariatric surgery.”

Mathur and her colleagues are conducting further studies to explore the role this organism plays in human metabolism.