Body fat or obesity is caused by bacteria and not by laziness or over eating alone, according to research by Chinese scientists, as official media here reported bacteria, and not just gluttony or laziness, may be to blame.

The bacteria can actually make genes generate fat, a report in the state-run China Daily said on Wednesday quoting a research team led by Zhao Liping, a professor of microbiology and associate dean at the School of Life Sciences and Biotechnology at Shanghai Jiao Tong University.

They pointed out the precise link between a particular kind of bacteria and obesity, it said.

The paper was published on December 13 in the journal of the International Society for Microbial Ecology.

It showed that a pathogen, or infectious agent, isolated from the gut of an obese human induced obesity and insulin resistance in germ-free mice.

In the clinical study, researchers found an excessive growth of endotoxin-producing bacteria, accounting for 35 per cent of the gut bacteria, in an obese patient whose initial weight was 175 kg, the report said.

After an intervention with specialised nutritional formula, the bacteria decreased to non-detectable amounts and the patient lost 51.4 kg.

It provided the key piece of evidence.

The patient also recovered from hyperglycemia and hypertension, it said. The intestinal bacterium involved was Enterobacter cloacae.

“The endotoxin released by the bacterium can activate a gene that helps generate fat and it also deactivates a gene that consumes fat,” it quoted Zhao at a news briefing at Shanghai on Tuesday.

Zhao’s study on the connection between obesity and gut microbiota came from personal experience.

In 2004 when he read the findings about a connection between obesity and gut microbiota in mice, he wondered if such a link existed in humans.

Then he began a diet that combined whole grains and fermented foods, such as yams and bitter melon.

After two years he lost 20 kilograms.

“Intestinal bacteria play an indispensable role in the genesis and development of chronic diseases, such as obesity, diabetes and coronary heart disease.

“The study will help find how bacteria affect us,” Zhao said.

“There are many reasons for obesity, such as lack of physical activity, increased calorie intake, genes, environment and intestinal bacteria,” Zhao said.

“The new research provides a direction to fight obesity,” he said.