Benchmark · Index v1.0 · Data as of Oct 10, 2026
GLP-1 Performance Index
One number per medication: how much weight it takes off for each unit of side effects it causes, from its main Phase 3 obesity trial. Higher is better.
The ranking
Weight loss per unit of side-effect burden. Phase 3 trials only.
* Wegovy pill: small trial with dose reductions. OASIS 4 included 307 adults, only about 205 of them on the pill, against 1,961 in STEP 1 for the injection, so its side-effect rates are less reliable. In addition, 18.6% of participants who completed treatment ended on a lower dose than 25 mg, which probably kept some from stopping and lowered the reported 6.9% discontinuation rate. Its ranking against the injection should be treated as provisional.
More weight loss, fewer side effects
Each dot is one medicine's main trial. Top left is best. Dashed line: drugs no other drug beats on both axes.
The numbers behind the index
| Drug | Weight loss | Nausea | Vomiting | Diarrhea | Constip. | Quit | Stomach | Burden | Index |
|---|---|---|---|---|---|---|---|---|---|
| TirzepatideSURMOUNT-1 | 22.5% | 31.0% | 12.2% | 23.0% | 11.7% | 6.2% | 19.5 | 25.7 | 8.8 |
| RetatrutideTRIUMPH-1 | 28.3% | 42.4% | 25.3% | 32.0% | 26.1% | 11.3% | 31.5 | 42.8 | 6.6 |
| CagriSemaREDEFINE 1 | 22.7% | 55.0% | 26.1% | n/r | 30.7% | 6.0% | 37.3 | 43.3 | 5.2 |
| Oral semaglutide 25 mg*OASIS 4 | 16.6% | 46.6% | 30.9% | 17.6% | 20.1% | 6.9% | 28.8 | 35.7 | 4.6 |
| Semaglutide 2.4 mgSTEP 1 | 16.9% | 44.2% | 24.8% | 31.5% | 23.4% | 7.0% | 31.0 | 38.0 | 4.5 |
| OrforglipronATTAIN-1 | 12.4% | 33.7% | 24.0% | 23.1% | 25.4% | 10.3% | 26.6 | 36.9 | 3.4 |
Methodology
Formula. Stomach score = average of the nausea, vomiting, diarrhea and constipation rates (at least three of four must be published). Side-effect burden = stomach score + quit rate, the share of people who stopped because of side effects, counted once. Index = average weight loss ÷ burden × 10.
Why quitting counts once. Because the stomach score averages four symptoms, one point of quit rate already weighs as much as four people each having one symptom. Most people who quit also had stomach side effects that are already counted, so a higher weight would count them twice. With weights of 0, 2 or 3 the order of the drugs stays the same.
Who qualifies. A completed Phase 3 obesity trial, published side-effect and discontinuation rates, and at least 10% average weight loss. Phase 2 compounds are tracked in the database but not ranked.
Data. Highest dose in each drug's main Phase 3 obesity trial in adults without diabetes. Weight loss uses the on-treatment (efficacy) estimand where reported. Rates are raw, not placebo-adjusted.
Limitations. Separate trials of different lengths (64 to 80 weeks) and populations, not a head-to-head comparison. Severity is not captured. Other benefits, such as semaglutide's proven heart protection, and other side effects, such as retatrutide's skin-sensation changes, are not part of the score. Drugs whose main trial enrolled fewer than 500 people are marked with an asterisk.
The index ranks medications on trial averages; it is not a recommendation for any individual. Full methodology, sensitivity check and live weighting slider →