Eli Lilly’s next-generation obesity drug led to what appears to be the most weight loss seen so far in a late-stage trial, but rates of side effects were high and many participants discontinued the treatment, including people who felt they were losing too much weight.

In a 68-week Phase 3 study of patients with obesity and knee osteoarthritis, those who took the highest dose and stayed on the drug, called retatrutide, lost 28.7% of their weight. When analyzing all treated participants, including those who discontinued, the efficacy was 23.7%, Lilly said Thursday.

Among the cohorts of treated patients, discontinuation rates due to adverse events ranged from 12% to 18%, compared with 4% in the placebo group. Lilly said the rates correlated with participants’ body-mass index at the start of

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