Fecal transplants from lean humans to obese humans have shown effects on weight loss.

“For instance, this idea that you could take obese mice and literally give them fecal transplants from lean mice, and yes, that sounds like what it sounds like. Fecal transplants definitely inserted through the same end in which it comes out. And I point that out because a lot of people have asked me that they-- and it was kind of scary to me, I thought, yes, this is not about ingesting feces, this is-- they literally do a transplant of these from lean mice into obese mice and the obese mice get lean.”