Could a fecal transplant from an overweight donor make the recipient gain weight?

A 32-year-old woman infected with Clostridium difficile was recently successfully treated with a fecal transplant, an emerging option for people who suffer from different gastrointestinal diseases, commonly caused by antibiotics. The idea is to take donor fecal matter (that has been rinsed and strained) and with either an enema, endoscopy or pill form, replace healthy […]

A 32-year-old woman infected with Clostridium difficile was recently successfully treated with a fecal transplant, an emerging option for people who suffer from different gastrointestinal diseases, commonly caused by antibiotics.

The idea is to take donor fecal matter (that has been rinsed and strained) and with either an enema, endoscopy or pill form, replace healthy bacteria in the gut.

The woman is reportedly healthy now, except for the fact that she began gaining weight, according to Open Forum Infectious Diseases. That might not seem so weird initially, she was feeling better and things were working right.

But the woman who received the implant never struggled with her weight before, and the donor, who was actually her 16-year-old daughter, ended up struggling with her weight soon after, indicating that her metabolism could have been in the process of changing at the time of the transplant. Could be coincidental, but researchers wanted to know if there could somehow be a correlation.

At the time of the transplant, the woman was a healthy 136 pounds with a normal BMI of 26 and her daughter weighed 140 pounds with a BMI of 26.6, but gained weight shortly after to 170 pounds.

Sixteen months later, the woman unintentional gained of 34 pounds, and by two and half years later she weighed 177 pounds and wasn’t responding to a medically supervised liquid protein diet and exercise program.

“We’re questioning whether there was something in the fecal transplant, whether some of those ‘good’ bacteria we transferred may have an impact on her metabolism in a negative way,” case report author Dr. Colleen Kelly of Warren Alpert Medical School, Brown University said in a statement.

Animal studies have shown that fecal transplant from an obese mouse into a normal-weight mouse can cause a significant increase in fat. So that might be a reason to believe there’s a causal thing happening. But she could have also gained weight simply because her infection was cleared up and her appetite increased.

The main reason some sort of correlation seems possible is because both she and her daughter gained weight. There isn’t enough information for it to be definitive, but surely as the procedure becomes more wide spread researchers will either find this to be more common or be able to rule it out.