When I first started looking into retatrutide, the weight-loss numbers were hard to miss. This is the study behind one of the most widely shared figures: 24.2%.
What happened in the study?
Jastreboff and colleagues studied 338 adults with obesity, or overweight and a weight-related condition, who did not have diabetes. People were assigned by chance to retatrutide or placebo — a comparison treatment without the active medicine — for 48 weeks.
By the end, the highest-dose group had lost an average of 24.2% of their starting weight, compared with 2.1% in the placebo group. That is a substantial difference. It is also an average, not a promise about what would happen to you or me.
The other part of the result
Stomach and bowel side effects were the most common, and were generally mild to moderate. Heart rate also increased in a dose-related way, peaking at around 24 weeks before declining.
The trial was funded by Eli Lilly. It gives us evidence of weight reduction with a defined medicine and clinical supervision. It cannot settle every question about years of use, or establish benefits for ADHD, migraine or addiction.
That distinction matters to me because my own curiosity goes beyond weight. Wanting answers is not the same as already having them. Nor can this trial tell us what is in a vial bought online.
The paper is “Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial”, published in the New England Journal of Medicine in 2023, DOI 10.1056/NEJMoa2301972. My longer Spotlight explores why these questions became personal.