Your gut bacteria ISN'T making you fat

Losing weight is a constant battle faced by people all over the world.

It is thought obesity is caused by overeating - but in recent years scientists have theorised that it may be linked to an imbalance of bacteria in the gut.

It is already known that a person's bacteria profile - known as microbiome - influences the risk of health problems from heart disease and inflammatory bowel conditions to type 2 diabetes - and experts believed it affected weight too.

But now, researchers from University of Michigan have dispelled the idea that this is why people put on extra weight.

It may also disappoint companies that sell products aimed at altering the gut's bacteria through fibre, nutrients and 'good' bacteria, researchers said.

There is no clear difference in the bacteria found in the digestive system of obese people and those of a healthy weight, they discovered.

The team looked at 10 previous studies conducted on the link between the microbiome and obesity.

A classification model, which takes into account all the data about the different bacteria present in an adult's stomach, was created.

This was used to try and predict whether that individual was obese or not, but it didn't work in nine of the earlier studies.

Study author Professor Schloss said more work needs to be done to clarify 'what we know and don't know' about how people get fat.

He added: 'There really is no one "healthy" microbiome.

'You could look at hundreds of people and they could all have very different populations of microbes in their guts. 

'So the idea we can correct your microbiome by doing one simple thing also doesn't hold up.'

But healthy eating habits which give stomach bacteria lots of fibre and nutrients could help people to lose weight, he adds.

Joint author Dr Marc Sze believes it's important to understand why people become obese due to the ongoing epidemic.

He said: 'Obesity is currently a health risk of epidemic proportions, and many have suggested the bacterial microbiome is not only different between obese and non-obese but also can predict obesity.

'We wanted to see if this was really what the existing literature suggested, since these claims could have a lot of positive impact on the management of this epidemic if true.' 

They are now developing a similar tool to assess the link between gut bacteria and its links to colon cancer.

It is hoped their findings will allow for a new diagnostic tool to detect colorectal tumours. 

The research was published in the journal mBio. 

Follow NEWS.am Medicine on Facebook and Twitter