FMT in obesity: bibliometric overview and review of 21 clinical trials
Metabolic benefits of FMT in obesity are transient and highly variable across individuals, and current evidence does not support routine clinical use.
| Population | Adults with obesity or overweight enrolled in 21 clinical trials identified via PubMed |
|---|---|
| Intervention | Fecal microbiota transplantation (FMT) via various routes and protocols |
| Comparator | Variable by trial (placebo, active control, or no comparator in some studies) |
| Outcome | Overall metabolic improvement after FMT; Durability of metabolic effects; Protocol standardization (donor selection, delivery route); Long-term safety of FMT; Publication trends and research collaborations |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Overall metabolic improvement after FMT | Not calculable; narrative review only, in the pooled estimate, in the 95% CI reported | — | Low | — | 21 studies |
| Durability of metabolic effects | Qualitative finding: effects described as transient across 21 trials; in the pooled estimate available | — | Low | — | 21 studies |
| Protocol standardization (donor selection, delivery route) | No standardized protocol identified across 21 trials; qualitative assessment only | — | Very low | — | 21 studies |
| Long-term safety of FMT | Not assessed; in the quantitative safety data reported in review | — | Very low | — | |
| Publication trends and research collaborations | Descriptive: 517 publications; China 246/517 (47.6%); Gut Microbes top journal (21 publications, IF 10.931) | — | Low | — | 517 studies |
Context
Obesity affects over one billion people worldwide and involves gut microbiota dysbiosis, chronic low-grade inflammation, and insulin resistance. FMT has emerged as a microbiota-restoration strategy, but its clinical role remains undefined. The absence of standardized protocols and large-scale trials limits practical conclusions.
What the study showed
The review of 21 clinical trials found that metabolic improvements following FMT are frequently transient and inconsistent across individuals. No standardized protocol exists for donor selection, delivery route, or outcome measurement. Most trials had small sample sizes. Pooled effect size estimates (RR, OR, SMD, 95% CI) were not calculated, as no meta-analysis was performed.
How it was done
Two-component study: (1) bibliometric analysis of 517 publications retrieved from the Web of Science (WoS); (2) narrative mini-review of 21 clinical trials on FMT in obesity identified in PubMed. No quantitative meta-analysis was conducted. No formal risk-of-bias assessment of included studies was reported (RoB 2 or ROBINS-I not applied).
Effect magnitude
No pooled effect size was calculated. The study qualitatively describes effects, when present, as transient and heterogeneous — without providing 95% CI or consolidated numerical estimates.
Risk of bias
Absence of quantitative meta-analysis precludes reliable effect estimates. Risk of bias in the 21 primary clinical trials was not formally assessed (no RoB 2 or ROBINS-I applied). Predominance of Chinese publications (47.6%) introduces geographic and publication bias. Heterogeneity of protocols across clinical trials prevents direct comparisons.
What this study does NOT prove
This study does not prove FMT efficacy in obesity — it is a bibliometric and narrative review without meta-analysis. It establishes no causality, determines no reliable effect size, and is not generalizable beyond the populations in the included trials.
In clinical practice
Clinicians should not offer FMT as a routine intervention for obesity based on current evidence. Larger trials with standardized protocols are required before any recommendation. Long-term safety monitoring remains undefined.
Limitations
Absence of quantitative meta-analysis precludes reliable effect estimates. Risk of bias in the 21 primary clinical trials was not formally assessed (no RoB 2 or ROBINS-I applied). Predominance of Chinese publications (47.6%) introduces geographic and publication bias. Heterogeneity of protocols across clinical trials prevents direct comparisons.
What is still missing
Multicenter randomized clinical trials with adequate sample sizes, uniform donor selection protocols, and extended follow-up are the mandatory next step. Studies must standardize outcomes and assess durability of metabolic effects.
Technical appendix
Version history
- 1.0 · 2026-06-26 — Auto-generated under Evidence Standard v1.0