*2.1. Sample Collection*

Secondary analysis was conducted on a single-center, double-blind, randomized, placebo-controlled pilot trial of FMT in obese metabolically normal/healthy patients (body mass index (BMI), 35 kg/m2 or higher without diabetes, metabolic syndrome, or nonalcoholic fatty liver disease). Briefly, patients were randomized 1:1 to receive FMT (via an induction dose of 30 FMT capsules followed by two maintenance doses of 12 capsules at week 4 and week 8) or an identical placebo capsule. A single healthy lean (BMI 17.5 kg/m2) donor was used to generate FMT capsules. A total of 22 patients were enrolled, 11 in each arm, and primarily female [10]. Samples collected at baseline (prior to FMT intervention) and after 4 weeks of intervention were available from 8 placebo and 11 FMT patients. Two patients in the placebo group withdrew from the study, and one placebo sample was unavailable at the 4-week time point. We focused on the 4-week time point because this was the time point at which the most substantial FMT-induced change in the bile acid profile was detected [10].
