Overview

• The 2024 BMJ Nutrition, Prevention & Health study had reported 6–8 kg weight loss and roughly 2.7–3.0 BMI-point reductions over 12 weeks in 120 overweight adolescents and young adults.
• Independent statisticians engaged by BMJ could not replicate the results, identified multiple analytical errors and implausible values, and noted patterns inconsistent with random allocation.
• The reviewers said participant-level data require further scrutiny, and BMJ advised that journalists and others should no longer cite the study’s conclusions.
• The authors described the discrepancies as honest mistakes related to data versions or formatting but agreed with the decision to retract the paper.
• BMJ’s journal editor said publishing an unregistered trial was the wrong call, following months of external critiques that flagged methodological shortcomings and inadequate reporting.