A new meta-analysis suggests there is no link:
“Popular hypotheses suggesting actionable links between obesity and the bacterial makeup of the human digestive system are difficult to support, a new analysis concluded.
The analysis examined 10 previous studies on the topic, and raises doubts over those studies’ suggestions that a certain “signature” in the digestive systems or microbiomes of obese mammals might increase a person’s likelihood of weight gain or obesity, reported Patrick Schloss, PhD, and Marc A. Sze, PhD, both of the University of Michigan in Ann Arbor, in mBio.”
Source: Gut Bacteria and Obesity: How Strong a Link? | Medpage Today