Fecal microbiota transplantation (FMT) has been recently implemented as a treatment for stubborn C. difficile infections (often incurred in hospital environments after the use of antibiotics). Once a patient’s gut microflora has been obliterated by courses of antibiotics, susceptibility to pathogens is high and a successful approach has been the actual movement of healthy fecal matter, containing a diverse and abundant commensal bacteria environment from florid individuals’ intestinal tracts to antibiotically-ravished guts. Results are typically without complication and very beneficial, but there is an interesting case study where a patient experienced atypical weight gain after receiving a FMT.
After undergoing 6 courses of antibiotics in attempt to eradicate a C. difficile and H. pylori infection, a woman finally recovered from H. pylori and C. difficile infections after receiving a fecal transplant from her daughter. The woman’s health improved but 16 months later she reported back with inexplicable and unintentional weight gain of 30 pounds, such that she was clinically obese. The preliminary inquiry is whether the weight gain was due to the fecal transfer, since the donor, her daughter, was obese. This question was raised due to the strange nature of her obesity, “She had been unable to lose weight despite a medically supervised liquid protein diet and exercise program. Her serum cortisol and thyroid panel were normal. She has continued to gain weight despite efforts to diet and exercise. She has also developed constipation and unexplained dyspeptic symptoms,” and mice studies have shown that microbiota can dictate obesity. By transplanting fecal matter from twins discordant for obesity into mice, they found that the gut microbiota actually induced lean or obese phenotypes in the mice and that these differences were resolved when the mice were co-housed (and supposedly exchanging microfloral components).
The fact that this is just a case study and also the fact that there are other explanations of the weight gain, such as the resolution of the H. pylori infection, which has been proven to decrease grehlin (the hunger signal) and to be associated with lower rates of obesity. There is much inquiry to be done to investigate whether one’s microbiota alone can dictate whether they are lean or obese, but there is certainly value in investigating it.