Can fecal microbiota transplantation (FMT) result in obesity? Here is an intriguing report published in Scientific American detailing excessive unintentional weight gain in a normal weight individual following FMT. The donor, a relative, also experienced similar weight gain. Of note, there are animal models suggesting that FMT can trigger or contribute to obesity.
We know that FMT is very successful for the management of recurrent C.difficile infection. There is much left to learn in the FMT field such as long term side effects or potential infectious complications from unknown pathogens.
One case report does not prove a cause and effect relationship between FMT and the onset of obesity. Regardless the finding underscores the need for a national registry or database for assessing both the efficacy and long term impacts of fecal transplantation.
In the meantime, for select patients, specifically, those with recurrent or persistent C.difficile, FMT is a reasonable and valuable treatment option in which the benefits seem to far outweigh the risks.