Yes, there has been some fascinating research coming out suggesting that the gut flora composition can have a causal effect on obesity. For example, if you tra

Yes, there has been some fascinating research coming out suggesting that the gut flora composition can have a causal effect on obesity. For example, if you transplant feces from overweight humans and normal weight humans to mice, the mice will gain (or not gain) weight, depending on which person the feces came from: https://www.science.org/doi/10.1126/science.1241214 https://www.science.org/doi/10.1126/science.1241214