The findings, from an international team of scientists, also suggest that a diet heavy in fiber could change the makeup of these germs, possibly making it easier for people to shed pounds.
“We know gut bacteria affect health and obesity, but we don’t know exactly how,” said Dusko Ehrlich, a co-author of the two new studies and coordinator of the International Human Microbiome Standards project.
The research finds that “people who put on the most weight lack certain bacterial species or have them at very low levels. This opens ways to develop bacterial therapies to fight weight gain,” he said.
Experts believe the gut, where the body processes food, is crucial to weight gain and weight loss.
“It is now well known that bacteria in our gut play an important role in our health and well-being, possibly as important as our own immune response and proper nutrition,” said Jeffrey Cirillo, a professor at Texas A&M Health Science Center’s department of microbial pathogenesis and immunology. “This means that disruption of the bacteria in our gut by use of antibiotics or eating foods that help only particular bacteria grow can have effects upon our entire bodies.”
A study released last March in the journal Science Translational Medicinesuggested that gastric bypass surgery led to weight loss — in mice — because it changed the makeup of the bacteria in their intestines.
In one of the new studies, which are both published in the Aug. 29 issue of the journal Nature, researchers analyzed the gut bacteria of 169 obese Danish people and 123 Danish people who were not obese.
The gut germs in the obese people were less diverse than in the others, and had more abnormalities in terms of metabolism. Also, obese people with a less diverse supply of germs gained more weight.
It’s not clear how the bacteria and obesity are related. But the research suggests that the metabolisms of the germs themselves are connected to the overall metabolism in the humans where they live, Cirillo said.
The finding could also have a practical application, the researchers said.