The review of animal and human studies, published in Mayo Clinic Proceedings, find these bacteria -- gut microbiota -- the trillions of bacteria populating the human gastrointestional tract -- may play a role in regulating weight and modifying these bacteria could become a treatment option for obesity.

Study lead author Dr. John DiBaise of the Mayo Clinic Arizona says much more research is needed. For instance, researchers need to prove or disprove the possible relationship between the gut microbiota and the regulation of weight.

"In particular, it is essential to demonstrate unequivocally whether differences in gut microbiota in obese versus lean people are the cause or the result of obesity," DiBaise says in a statement.

The study authors suggest the next wave of research explore the safety and feasibility of modifying the gut microbiota in clinical trials involving humans.

"Although clearly no substitute for proper diet and exercise, manipulation of the gut microbiota may represent a novel approach for treating obesity that has few adverse effects," DiBaise says.