This story is over 5 years old.


Can Slim People’s Poop Treat Obesity?

We're all wondering. Now Canadian researchers are trying to find out.

Many people with obesity are willing to try almost anything to get to a healthy weight, including surgery. But could the answer to shedding pounds be as simple, and icky, as popping a pill filled with the poop of their slimmer peers?

Over the last few years, we've learned that gut bacteria differs dramatically between healthy-weight people and people with obesity. At the same time, interest in fecal transplants as a treatment for everything from superbugs to malnourishment has grown dramatically. As these discoveries have unfolded, we've all been wondering the same thing: can we just put the poop of skinny people into people with obesity to help them lose weight? Now, a team of researchers in Canada is trying to find out.


"If you, who are skinny, and I, who is a little fatter, eat the same amount of food, you'll suck up less nutrients and I'll suck up more," said Dr. Herbert Gaisano, a professor of medicine and physiology at the University of Toronto. "Part of the reason is because my bacteria metabolizes the food in a way that I'll suck up more."

With the help of a $1.5 million grant from the Canadian government, Gaisano and his team are trying to see if swapping the bacteria from a slim person's gut into a person with obesity through a fecal transplant will help that person lose weight. There's already some evidence that this may work. For one, studies on mice have shown that when germ-free mice were fed the stool of obese mice, or even humans, those mice put on weight. There's also evidence that people with obesity who get bariatric surgery not only lose weight from the physical changes, but also because of changes to their gut bacteria.

Gaisano and the other researchers are planning to test out the theory in two ways. First, they're going to see if germ-free mice gain weight when given the stool of patients prior to bariatric surgery, and then collect stool from those same patients six months later to see if it makes fat mice lose weight (or stop gaining).

They also plan on doing a very small trial of fecal transplants in humans: taking the stool from healthy weight individuals and transplanting it into the large intestine of people with morbid obesity. They'll compare this group with a control group to monitor the effects.


"We will choose really healthy, you know, bicyclist types and do eight or 10 patients," Gaisano said. "We'll do a procedure like a colonoscopy to guide the fecal transplant to the cecum [a pouch at the start of the large intestine], and put like five syringes full of real poo from these skinny volunteers. Then we'll follow them and see whether they lose weight."

Gaisano said this point, they're basically just testing out a hypothesis: will this even work? But even if it does, there are a lot of other factors to consider before this could be a widespread treatment for obesity.

"Some healthy [weight] people might not be healthy. What if they have a predisposition to cancer?" Gaisano said. "There's evidence that it can have something to do with the interaction with bacteria. You could be making someone really skinny, but could you be giving them cancer 20 years from now? We need to be really careful."

For the purpose of this small trial, Gaisano said they will be doing a family history analysis and scanning the fecal samples for diseases that may be transmittable, like HIV. But in the future, for this treatment to ever get to the point of widespread viability, donors would need to be screened for genetic factors too.

Still, he's optimistic the study will show some promising results and that with proper screening, this could someday offer a safe, less-invasive, less-expensive option than surgery for people with obesity. Though, they'll need to get over the ick-factor.

"You want to get cut up or you want to eat a couple pills of poo? It's yucky, yeah, but it's in a capsule you won't even smell it," Gaisano said with a laugh. "We should say they're taking super-probiotics, or skinny probiotics, or something 'biotic.' Then they'll say 'that's a nice thing to hear. I'm not eating shit.' It's marketing."