It is not uncommon to lose weight following GI infections, particularly if you are still having loose stools or diarrhea. I lost 20 pounds in three months because I kept relapsing a week after finishing antibiotics (even after no longer testing positive for CDiff or any other parasite). What I think has finally started to turn things around for me is the diet. My nutritionist told me in simple terms that the bad bacteria and imbalance (dysbiosis) left in your gut after the infection and (yes) by the antibiotics, highjacks and steals nutrition from being absorbed by your body which leads to malnutrition and weight loss. This is why it is so important to make changes in diet following these infections to allow your gut to heal and not feed bad bacteria until that gut balance is restored. I think this principle applies to CDiff, IBS, SIBO and other intestinal conditions that can lead to malabsorption of nutrients. A red flag went up for me when you said you ate a lot over the Thanksgiving weekend. I took three rounds of antibiotics, would do alright for a week or so thereafter, and then quickly relapse back to diarrhea (even after no longer showing signs of active infection). Everyone kept telling me to eat normal again after the antibiotics so I could gain weight back, and that inevitably contributed to more loose stools, diarrhea, and further weight loss, creating a vicious cycle for me. I knew that what I was putting into my mouth was contributing to my symptoms but never imagined that foods like yogurt, rice or a baked potato could make me worse. The idea is to limit dairy, gluten, complex carbs and refined sugars for a while to “kill” the overgrowth of bad bacteria and make sure they do not return to repopulate your gut after the antibiotic. Let me know if you want me to explain in more detail what I am doing and I also recommend you look at Low FODMAPs and SCD diet. I am working with a nutritionist and using aspects of both. I finished my last round of antibiotics on Nov 15 and I am now on my tenth day of having normal looking and solid stools, and also gained four pounds. I am cautiously optimistic but the only thing I have changed this time is what and how I eat. Hope this helps.