In 2011, a 32-year-old woman underwent a fecal microbiota transplant (FMT) to treat a persistent Clostridium difficile infection.
The donor was her 16-year-old daughter, who was overweight but otherwise healthy.
Following the procedure, the woman experienced significant weight gain, becoming obese despite no changes in her diet or exercise habits.
The Unforeseen Outcome
Initially weighing 136 pounds with a BMI of 26, the woman gained 34 pounds within 16 months post-FMT, reaching a BMI of 33.
Even with a medically supervised diet and exercise program, her weight continued to increase, eventually reaching 177 pounds and a BMI of 34.5.
Exploring the Possible Causes
Researchers, including Dr. Colleen R. Kelly from the Warren Alpert Medical School of Brown University, are investigating whether the FMT introduced bacteria that affected the woman’s metabolism.
Animal studies have shown that transferring gut bacteria from obese to healthy mice can lead to weight gain, suggesting a similar mechanism might be at play in humans.
Additionally, the woman had a Helicobacter pylori infection, which was treated around the time of the FMT.
Some studies suggest that eradicating H. pylori can lead to weight gain due to changes in appetite-regulating hormones.
Implications for FMT Practices
This case highlights the need for careful donor selection in FMT procedures.
The researchers recommend avoiding overweight donors until more is understood about the potential metabolic effects of transferred gut bacteria.
Further studies are necessary to identify specific bacterial strains that could influence weight and to develop safer FMT protocols.
Conclusion
While FMT can be a life-saving treatment for certain infections, this case underscores the complexity of the human microbiome and the potential for unintended consequences.
Ongoing research is essential to ensure the safety and efficacy of microbiota-based therapies.
