Is there a ceiling effect for GLP-1-mediated weight loss? — my results so far

Short answer first, then the reasoning. Relative and absolute effects need reading together. A 20% relative reduction on a high baseline risk is a large absolute benefit; the same relative figure on a low baseline risk is a small one, and press summaries almost always quote the relative number because it is bigger.

BenResearch_OR said:

Relative and absolute effects need reading together.

Propensity score matching studies and the trial evidence: when RCTs aren't available for a specific question, propensity score-matched observational studies can provide useful evidence.

A recent PSM study of 18,000 GLP-1 users vs matched controls showed reduced all-cause mortality (HR 0.81) over 4 years of follow-up[1].

These results complement the RCT data and suggest the benefits translate to real-world populations.

raj_cambridge said:

I keep finding that the number in the press summary and the number in the paper are not the same number, and the difference is always in the same…

Same position here, arrived at the long way round. The gap between trial results and real-world results is consistent and it is not fraud. Trial participants get titration by protocol, scheduled contact, free drug and dietetic support; removing that infrastructure costs a few percentage points every time it has been measured. When your own curve sits below the published mean, that is the likeliest explanation before anything about you or your material.

Happy to go further on any of that.

From the other side of the consultation, briefly.

Forest plot interpretation for the the trial evidence meta-analysis: when reading the pooled estimate, pay attention to:

1. Point estimate (HR/RR/OR) — center of the diamond
2. Confidence interval width — precision of the estimate
3. I² statistic — heterogeneity across studies
4. Individual study weights — are results driven by one large trial?
5. Prediction interval — range of plausible true effects in future settings

The the trial evidence meta-analysis shows a pooled RR of 0.79 (95% CI 0.70-0.89), I²=37%. This is a robust and consistent effect.